Value of 18 F-FDG PET/CT in suspected neurological paraneoplastic syndromes

Abstract

Background: Paraneoplastic neurological syndromes (PNS) result from an underlying malignant tumor. However, in a significant number of patients, underlying primary tumor may remain undetected as conventional computed tomography (CT) imaging and onconeural antibodies have a low sensitivity to detect the occult tumor. Objectives: To evaluate the diagnostic performance of FDG PET/CT for detecting underlying tumor in patients with suspected neurological PNS. Materials and Methods: Retrospective analysis of findings from fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT scans of 143 patients from two PET/CT centers in north India was done and compared to findings of CT scans and onconeural antibody panel of these patients. Results: Overall, 39 (27%) patients had positive PET/CT findings. Of these, 24 (17%) patients were proven to have underlying malignant tumor. Among 104 FDG PET/CT negative patients, six (5%) patients were subsequently found to have an underlying malignant tumor on subsequent follow-up and workup. Therefore, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of FDG PET/CT for detecting underlying tumor were 80%, 86.7%, 61.5%, 94.2%, and 85.3%compared to sensitivity, specificity, PPV, NPV, and accuracy of 60%, 89.8%, 61%, 89.4%, and 83.5% for CT and 43.3%, 97.3%, 81.2%, 86.6%, and 86% for onconeural antibodies, respectively. Conclusions: FDG PET/CT should be preferred as an initial investigation for the detection of underlying malignancy in patients with suspected neurological paraneoplastic syndromes. It can help in the early detection of underlying malignancy in a significant number of patients with negative onconeural antibody and conventional CT results. However, a negative FDG PET/CT scan does not always rule out the possibility of an underlying malignancy, and a follow-up is indicated in such clinically suspected PNS cases.

Full text

66
Received: 15-March-2023, Revised: 20-April-2023, Accepted: 06-May-2023,
Published: 16-August-2023
Address for correspondence: Dr. Nitin Gupta,
Department of Nuclear Medicine, Dr. Rajendra Prasad Government Medical
College, Kangra, Himachal Pradesh 176001, India.
E-mail: Nittinplp@gmail.com
© 2023 Bengal Journal of Cancer | Published by Wolters Kluwer - Medknow
This is an open access journal, and articles are distributed under the terms of the
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows
others to remix, tweak, and build upon the work non-commercially, as long as
appropriate credit is given and the new creations are licensed under the identical terms.
For reprints contact: WKHLRPMedknow_reprints@wolterskluwer.com
How to cite this article: Gupta N, Kumar S, Sareen P, Negi M, Kaur
M, Singh M. Value of 18F-FDG PET/CT in suspected neurological
paraneoplastic syndromes. Bengal J Cancer 2022;2:66-76.
Original Article
Value of 18F-FDG PET/CT in Suspected Neurological
Paraneoplastic Syndromes
Nitin Gupta1,2, Sudesh Kumar3, Priya Sareen4, Muninder Negi5, Manpreet Kaur6,7, Meena Singh8
1Department of Nuclear Medicine, Dr. Rajendra Prasad Government Medical College, Tanda, Kangra, Himachal Pradesh, 2Depar tment of Nuclear Medicine, Post
Graduate Institute of Medical Education and Research, Chandigarh, 3Department of ENT/Otolaryngology, Dr. Rajendra Prasad Government Medical College, Kangra,
4Department of Reper tory, Homeopathic Medical College, 5Department of Radiation Oncology, All India Institute of Medical Sciences, Bilaspur, Himachal Pradesh,
6Department of PET/CT, PGIMER, Chandigarh, 7Department of Nuclear Medicine, Grecian Hospital, Chandigarh, 8Department of Neurology, PGIMER, Chandigarh, India
Abstract
Background: Paraneoplastic neurological syndromes (PNS) result from an underlying malignant tumor. However, in a significant
number of patients, underlying primary tumor may remain undetected as conventional computed tomography (CT) imaging and
onconeural antibodies have a low sensitivity to detect the occult tumor. Objectives: To evaluate the diagnostic performance of FDG
PET/CT for detecting underlying tumor in patients with suspected neurological PNS. Materials and Methods: Retrospective analysis
of findings from fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT scans of 143 patients from two PET/CT
centers in north India was done and compared to findings of CT scans and onconeural antibody panel of these patients. Results:
Overall, 39 (27%) patients had positive PET/CT findings. Of these, 24 (17%) patients were proven to have underlying malignant tumor.
Among 104 FDG PET/CT negative patients, six (5%) patients were subsequently found to have an underlying malignant tumor on
subsequent follow-up and workup. Therefore, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV),
and accuracy of FDG PET/CT for detecting underlying tumor were 80%, 86.7%, 61.5%, 94.2%, and 85.3%compared to sensitivity,
specificity, PPV, NPV, and accuracy of 60%, 89.8%, 61%, 89.4%, and 83.5% for CT and 43.3%, 97.3%, 81.2%, 86.6%, and 86%
for onconeural antibodies, respectively. Conclusions: FDG PET/CT should be preferred as an initial investigation for the detection
of underlying malignancy in patients with suspected neurological paraneoplastic syndromes. It can help in the early detection of
underlying malignancy in a significant number of patients with negative onconeural antibody and conventional CT results. However,
a negative FDG PET/CT scan does not always rule out the possibility of an underlying malignancy, and a follow-up is indicated in
such clinically suspected PNS cases.
Keywords: FDG PET/CT, neurological paraneoplastic syndrome, occult malignant tumor, onconeural antibodies, positron emission
tomography
IntroductIon
Paraneoplastic neurological syndromes (PNS) are a
rare group of clinical manifestations resulting from an
underlying malignant tumor but not directly caused by the
tumor or its metastasis in the brain.[1-3] PNS occurs in less
than 1% of patients with a malignant tumor.[2] In most of
the patients, symptoms of PNS precede the detection of
underlying tumor.[4,5] PNS may affect the central nervous
system, peripheral nervous system, or neuromuscular
junctions and, thus, present with complex neurological
signs and symptoms, and as such, their diagnosis is
often difficult and delayed.[4,6-8] PNS are thought to be
immunologically mediated,[3,4,9-12] resulting from the
production of certain types of onconeural antibodies.[4,13,14]
These antibodies are common to both neural tissue and
Access this article online
Quick Response Code:
Website:
https://www.bengaljcancer.org
DOI:
10.4103/bjoc.bjoc_8_23
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDGPET/CT
Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022 67
underlying tumor, and thus mount an immune response,
causing irreversible neuronal damage.[9,15]
In a considerable number of patients, clinical
manifestations of PNS may precede the detection of
underlying malignant tumor, by an interval ranging
from 4–6months to even up to 4years.[4,5,12] While PNS
may present in virtually all types of malignancies, it
is considered to be most commonly associated with
small cell lung cancer, whereas nonsmall cell carcinoma
lung, carcinomas of breast, ovary, thymus, testes, and
lymphoma are other common malignancies associated
with PNS.[9,16-18]
Because PNS can present with a myriad of neurological
symptoms, not specific for any particular syndrome, their
diagnosis presents a great dilemma to the neurologist,
more so in patients with negative onconeural antibodies.
In September 2019, an international panel of experts
(PNS-Care panel) suggested that the criteria for
diagnosis of definite PNS solely based on the presence
of onconeural antibodies are no longer adequate because
of their frequent absence in patients with PNS or even
because of their occasional presence in patients without
PNS.[9,13,19,20]
Definite treatment of PNS involves tumor-specific
therapy to remove the tumor or reduced tumor burden
and, hence, underlying antigenic cause of paraneoplastic
symptoms.[6] Therefore, detection and localization of
underlying malignant tumor at an initial stage is of
utmost importance in planning specific treatment of these
patients.[6,21,22]
18F-fluorodeoxyglucose (FDG) positron emission
tomography (PET)/computed tomography (CT) has
better sensitivity compared with conventional CT scan
the in detection of malignant tumors, because it combines
anatomical imaging with metabolic information.[16,23,24]
Furthermore, occasionally in patients with suspected PNS,
underlying primary tumor may be located in a region of
the body otherwise not clinically suspected and detected
incidental to the clinical presentation.[25] In such cases,
FDG PET/CT scan offers advantage of whole-body
screening in one examination session and, hence, improves
sensitivity for the detection of underlying tumor.[16,23,24,26,27]
A significant number of incidentally detected FDG
PET/CT are found to be malignant on histopathological
evaluation.[28,29] FDG PET/CT may also be helpful in the
detection of a metachronous or synchronous tumor in
such patients.[30-32]
In the present study, we aimed to evaluate the utility of
18F-FDG PET/CT in suspected PNS and determine its
sensitivity and specificity in the detection of underlying
malignant pathology irrespective of onconeural antibody
status and compared the result to those of CT and
onconeural antibody investigations.
MaterIals and Methods
Patient selection and data collection
In this retrospective study, 18F-FDG PET/CT scans and
medical records of patients, referred with suspected
PNS between January 1, 2013, and March 31, 2022, at
two PET/CT centers (Postgraduate Institute of Medical
Education and Research, Chandigarh, and ST PET/
CT and Theranostics Centre, Chandigarh) in North
India were reviewed and analyzed. Patients whose case
details were unavailable or whose diagnoses were not
made in consultation with a neurologist and those who
could not be followed up for at least a minimal required
period of 4years[4,19] were excluded from the study. Patient
demographic information, clinical presentation, and
previous imaging and onconeural antibodies investigation
findings were recorded from case notes as available. All
patients with positive FDG PET/CT scan were followed
up for results of further investigations to confirm the
finding of FDG PET/CT scan both in terms of final
histopathological and neurological diagnosis. Patients
with a negative FDG PET/CT examination were also
followed up to find their eventual outcome for an average
time of 4years from their FDG PET/CT scan. Afinal
diagnosis of PNS was based on documentation of this
diagnosis by the consulting neurologist.
FDG PET/CT protocol
The patients had undergone FDG PET/CT scans on
either GE Discovery STE 16 slice or GE Discovery STE
64 slice PET/CT scanners (GE Healthcare, Waukesha,
Wisconsin). FDG in a dose range of 300–370 MBq
(8–10 mCi) was given intravenously to the patients after
a minimum of 6 h of fasting and with blood glucose levels
below 180 mg/dL. Sixty minutes after the tracer injection,
contrast enhanced computed tomography followed by
PET images were acquired from the skull base to mid-
thigh. IV and oral contrast were used in all patients where
not contraindicated. The images were generally taken at
7–8 bed positions and 2–3 min/bed position.
Interpretation criteria for 18F-FDG PET/CT imaging
18F-FDG PET/CT scan images were analyzed and interpreted
into three categories depending on the FDG uptake and
CT image findings. The three categories included (A) likely
malignant with an increased FDG uptake (standardized
maximum uptake value [SUVmax] > 2.5) on PET images
and morphological features suggestive of malignant nature
of the lesion on CT images, (B) suspicious for malignant
pathology where there was FDG uptake significantly more
than liver uptake and suspicious morphological appearance
of the lesion not consistent with a benign pathology or
anatomical/physiological variations, and (C) normal or
negative for malignancy with either FDG uptake consistent
with a physiological pattern and/or increased FDG uptake
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDG PET/CT
68 68 Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022
(SUVmax > 2.5) with CT findings typically suggestive of
an inflammatory or benign pathology.
Statistical analysis
Parametric distributed data were presented as mean ±
standard deviation. Nominal and categorical variables
were presented as frequencies and percentages. The
statistical analyses were performed using MedCalc for
Windows, version 19.4 (MedCalc Software, Ostend,
Belgium). Sensitivity, specificity, positive predictive value,
negative predictive value, and accuracy were calculated.
results
Patient demographics
A total of 256 patients were identified who had undergone
FDG PET/CT for suspected PNS between January 1,
2013, and March 31, 2022. Among these, 19 patients had
been previously treated, for a known malignancy at some
point in their clinical history and had been referred for
PET/CT with suspicion of a recurrence. All patients in
whom case details were unavailable or those who could not
followed up (n=22), and those in whom brain metastasis
was found (n=17) were excluded from the study. Besides,
those patients in whom onconeural antibodies or previous
CT had not been performed (n=74) were also excluded
from the study. The final study, therefore, included a total
of 143 patients (79 males and 64 females), with a mean age
of 63 ± 15years.
Observations and analysis
Onconeural antibody findings
All patients included in the final study had undergone
onconeural antibody testing within a time span of 6–8
weeks preceding their FDG PET/CT scans. Anti-Hu,
anti-Yo, anti-CV2, anti-amphiphysin, anti-Ma2, anti-Ri,
and anti-SOX1 had been tested as part of PNS screening
in high-risk patients. In addition, other antibodies were
also tested when clinically indicated.
Overall, positive results were returned in 16 (11%) of
these patients. Anti-Hu (n =5) and anti-Yo (n= 6) were
the most commonly encountered antibodies, whereas
other antibodies were encountered less commonly. The
association of detected antibodies with respective type of
cancer and PNS is depicted in Table 1.
Among 30 patients with underlying biopsy-proven
malignancy, 13 (43%) had positive onconeural antibodies,
and 17 were negative. Three patients with positive
onconeural antibodies were negative for underlying
malignancy on biopsy and at the end of follow-up period.
Sensitivity and specificity of onconeural antibodies for
underlying malignant tumor were, therefore, 43.3% and
97.3%, respectively [Table 2].
Conventional CT scan findings
All patients had undergone regional diagnostic CT scans
before FDG PET/CT scan with a mean time interval
of 4–6 weeks. A total of 74 patients had undergone CT
imaging of the thorax and abdomen, 35 patients had
undergone CT thorax alone, 22 patients had undergone
CT abdomen and pelvis, and 12 patients had undergone
CT head andneck.
A total of 27 patients (18%) had positive or suspicious
CT findings for an underlying malignant tumor. In 15
(10%) patients, malignancy was biopsy proved, whereas
in 12 patients (8%), benign/inflammatory pathology was
proven.
Of the 116 (82%) patients in whom primary tumor could
not be detected or localized on regional CT scans, nine
(6%) patients subsequently had underlying primary tumor
localized on whole-body PET/CT. Overall, the sensitivity
and specificity of CT for detecting the underlying
malignant tumor were 60% and 89.8%, respectively
[Table2].
18F-FDG PET/CT findings
A total of 39 patients (27%) had positive or suspicious
findings for an underlying malignant tumor on FDG
PET/CT scans. Malignancy was proven on biopsy in
24 (17%) of these patients [Table 1 and Figures 1–3],
whereas in 15 (10%) patients, benign/inflammatory
pathology was proven. The FDG PET/CT finding, tumor
histopathological diagnosis, onconeural antibody status,
and neurological diagnosis are listed in Table 1.
In three (14%) patients with already diagnosed or
treated malignancy who were in remission, FDG avid
heterogenous soft tissue lesions were detected at a
different region from the previously known malignancy
and subsequently proven as metachronous (two patients)
or synchronous tumors (one patient) on histopathology.
In addition, two patients were detected to have FDG avid
heterogenous lesions at the primary site of previously
operated and resolved malignant tumor, which were
suspicious or equivocal for regional recurrence on CT
images.
In six (5%) patients with FDG PET/CT negative scans, two
patients were detected and proven to be malignant tumor
on magnetic resonance imaging (MRI) and subsequent
histopathology. In four other patients with initial negative
FDG PET/CT scans, malignant tumor was subsequently
detected and biopsy-proven during the course of follow-up
period up to 4 years after their initial PET CT scan.
Therefore, the sensitivity and specificity of 18F-FDG PET/
CT for the detection of underlying malignant tumor were
80% and 86.7%, respectively. Comparative performance
of FDG PET/CT versus CT and onconeural antibodies is
depicted in Chart 1 and Table 2.
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDGPET/CT
Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022 69
Table 1: FDG PET/CT findings compared to CT findings and onconeural antibody status in PNS patients with biopsy-proven
underlying malignancy
Pt. Neurological
symptoms
FDG PET/CT findings CT imaging findings Histopathology Antibody Neurological
diagnosis
1aIrritability, altered
personality, impaired
memory, seizures
FDG avid soft tissue intraocular
lesion, mediastinal lymph nodes,
lytic vertebral lesions
Cystic liver lesion,
mediastinal lymph nodes
vertebral lytic lesions
Choroidal
Malignant
melanoma
Anti-
NMDAR,
anti-Hu
Limbic
encephalitis
Non-FDG cystic avid liver lesion
2aDementia, diplopia,
vertigo, impaired
speech, and
imbalance,
FDG avid ill-dened thyroid
lesion, FDG avid lung nodules,
and nonavid pleural effusion
Lung nodules, pleural
effusion
Papillary
carcinoma thyroid
Negative Cerebellar
degeneration
3a Seizures,
impaired memory
hallucinations,
agitation
FDG avid heterogenous
spiculated lung lesion, minimally
FDG avid oor of mouth lesion
Residual Floor of mouth
lesion and subcentimetric
cervical lymph nodes
SCC oor of
mouth (known),
bmetachronous
adenocarcinoma
lung
negative Limbic
encephalitis
4 Pain and tingling in
bilateral upper limbs,
ataxia, impaired gait
FDG avid heterogenous Lung
mass, mediastinal LAP, and
adrenal lesion
Heterogenous Lung mass
and mediastinal LAP
Squamous cell
lung CA
Anti- Hu ataxic sensory
neuronopathy
5 Vertigo, involuntary
ocular and limb
movements, truncal
ataxia
FDG avid Multiple enlarged
Lymph nodes, and marrow-based
lesions
Abdominal and
Retroperitoneal LAP,
hepato-splenomegaly
NHL Anti-Hu,
anti-Yo
Opsoclonus-
myoclonus
syndrome
Hepato-splenomegaly
6 Paraplegia, diplopia,
dysphagia. Urinary
incontinence
FDG avid distal esophagus
and stomach mass, mediastinal
supraclavicular, and abdominal
LAP
Stomach and esophagus
mural thickening
Stomach
adenocarcinoma
Negative GBS
Abdominal lymph nodes
7aDiplopia, nystagmus,
and ataxia decreased
muscle tone
Focally FDG avid cystic ovarian
lesion, subcentimetric abdomino
pelvic lymph nodes [Figure 1]
Cystic adnexal lesion
subcentimetric abdomino
pelvic lymph nodes
Ovarian
adenocarcinoma
Anti-Yo Cerebellar
degeneration
8aSlurred speech,
dysphagia, limb
stiffness, weakness,
and muscle wasting
FDG avid Renal mass,
retroperitoneal and mediastinal
LAP, lung lesions, skeletal lesions
[Figure 2]
Bilateral lung lesions with
mediastinal LAP and lytic
rib lesion
Clear cell renal
carcinoma
Negative motor neuron
disease
9 Upper limb
weakness, dry mouth,
constipation, ptosis,
and diplopia
FDG avid cavitating lung lesion,
mediastinal LAP, and skeletal
lesions
Cavitating lung mass with
mediastinal LAP
Squamous cell
carcinoma lung
Anti-VGCC,
anti-Sox 1
Lambert eaton
syndrome
10 Headache, impaired
balance seizures,
slurred speech
FDG avid ill-dened breast lesion,
axillary LAP, liver lesion
Ill-dened breast
parenchyma thickening,
axillary lymph nodes, liver
lesion
IDC breast Negative Paraneoplastic
encephalomyelitis
11 Lower limb sensory
loss with difculty in
walking and climbing
stairs, urinary
incontinence
FDG avid ill-dened Lung lesion
with collapse and pleural effusion,
mediastinal LAP, adrenal, and
skeletal lesions
Heterogenous lung
consolidation pleural
effusion and mediastinal
LAP
Squamous cell
carcinoma lung
Negative Subacute sensory
motor neuropathy
12 Painful lower limb
and back muscle
spasms, rigidity,
vertigo, falls
FDG avid ascending colon
mural thickening, abdominal and
supraclavicular LAP
Ascending colon thickening,
abdominal lymph nodes
Adenocarcinoma
ascending colon
Amphiphysin Stiff Person
Syndrome
13 Fever headache
impaired balance
seizures, slurred
speech
FDG avid lytic skeletal lesions
with soft tissue component
Multiple lytic vertebral
lesions
Multiple myeloma Anti-Hu,
Anti-CV2
Limbic
encephalitis
14aLower limb muscle
weakness fatigue,
ptosis. diplopia
FDG avid pancreatic body lesion,
pyriform sinus heterogenous soft
tissue, heterogenous lung mass,
pleural effusion, retroperitoneal
LAP, and skeletal lesions
Pyriform sinus soft tissue
lesion, Lung heterogenous
mass, pleural effusion, and
skeletal lesion
SCC pyriform
sinus (known)
bsynchronous
pancreatic
adenocarcinoma
Negative Lambert Eaton
syndrome
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDG PET/CT
70 70 Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022
15 Dysarthria, gait
ataxia nystagmus,
dementia, muscular
pain weakness,
FDG avid heterogenous
adnexal lesion, pleural effusion,
ascites, supraclavicular, internal
mammary, mediastinal abdominal
and pelvic LAP
Heterogenous adnexal lesion
abdomino pelvic LAP, ascites
Ovarian
adenocarcinoma
Anti-Yo cerebellar
degeneration
16aAtaxia, twisting/
writhing movements
and weakness and
numbness of limbs
Ill-dened Prostate lesion
retroperitoneal and pelvic LAP,
lytic sclerotic skeletal lesions
Multiple skeletal
lytic sclerotic lesions
retroperitoneal LAP
Prostate
adenocarcinoma
Anti-Hu subacute sensory
neuronopathy.
17 Slurred speech,
limb wasting and
weakness, difculty
in buttoning and
walking
Focal FDG avid urinary
bladder thickening, pelvic
and retroperitoneal LAP, and
lung nodules, non-FDG avid
prostatomegaly
Bladder mural thickening
prostatomegaly
UB transitional
cell carcinoma
Negative Cerebellar
degenerartion
Pelvic and retroperitoneal
LAP
18 Ptosis, diplopia
dysphagia impaired
speech, upper limb
weakness
FDG avid heterogenous anterior
mediastinal mass, lung nodules,
mediastinal LAP
Heterogenous Mediastinal
mass with lung nodules,
mediastinal LAP
Malignant
thymoma
Anti AchR Myaesthenia
Gravis
19 Squint, muscle
spasms, irritability,
ataxia
FDG avid GB thickening,
abdominal, supraclavicular LAP,
nonavid liver hypodense lesions
Gall bladder mural
thickening, ill-dened
subcentimetric liver lesions,
and abdominal lymph nodes
Adenocarcinoma Negative Opsoclonus
Gall bladder Myoclonus
20aDysarthria,
dysphagia nystagmus,
ataxia
FDG avid stomach mural
thickening, abdominal LAP,
marrow-based lesions, non-FDG
avid MNG, and cervical lymph
nodes [Figure 3]
CT neck and thorax:
hypodense thyroid lesions
with retrosternal extension,
cervical LAP
DLBCL Negative Cerebellar
degeneration
21 Blurred vision with
diplopia, drowsiness,
limb weakness, and
paresthesias and
ataxia
Pelvic and retroperitoneal LAP,
lung nodules, pleural-based
lesions
Pelvic and retroperitoneal
LAP
Metastatic
Seminoma testes
Negative Paraneoplastic
Encephalomyelitis
22aDysphagia,
dysarthria, gait
ataxia, dementia
FDG avid breast lesion, axillary
mediastinal LAP, liver lesions, and
lung nodules
Cystic liver lesions, CT pelvis
WNL
Endometrial
carcinoma
(known)
Anti-Yo,
anti-Ri
Cerebellar
degeneration
b Metachronous
Breast carcinoma
23 Personality change,
acute confusional
state, hallucinations,
and seizures
FDG avid rectosigmoid
mural thickening, nonavid
subcentimetric pelvic lymph
nodes, and ascites
Ill-dened Rectosigmoid
anastomotic mural
thickening, subcentimetric
pelvic lymph nodes ascites
Rectal
adenocarcinoma
recurrence
negative Limbic
encephalitis
24 Bilateral decreased
visual acuity and
gradual painless
visual loss
FDG avid heterogenous perihilar
lung lesion, mediastinal lymph
nodes, few abdominal lymph
nodes, lytic vertebra lesions, non-
FDG avid pleural effusion
Heterogenous perihilar lung
lesion, pleural effusion,
mediastinal lymph nodes
Small cell
carcinoma lung
CRMP-5 IgG Paraneoplastic
optic neuritis
GBS: Gullian Barre Syndrome, LAP: lymphadenopathy.
aPatients where primary tumor was detected/localized on PET/CT, with CT scan reported negative for primary malignant tumor.
bMetachronous or synchronous tumor
Table 1: Continued
Pt. Neurological
symptoms
FDG PET/CT findings CT imaging findings Histopathology Antibody Neurological
diagnosis
Table 2: Comparative performance of 18F-FDG PET/CT, conventional CT, and onconeural antibody in the detection of underlying
tumor in suspected PNS
Modality Sensitivity (%) (95% CI) Specificity (%) (95% CI) PPV (%) (95% CI) NPV (%) (95% CI) Accuracy (%) (95% CI)
18F-FDG PET/CT 80 (61.4–92.3) 86.7 (79.0–92.4) 61.5 (49.1–72.6) 94.2 (88.8–97.1) 85.3 (78.4–90.6)
CT scan 60 (38.6–78.8) 89.8 (82.9–94.6) 61.1 (45.6–74.5) 89.4 (83.4–93.2) 83.5 (76.4–89.2)
Onconeural antibody 43.3 (25.4–62.5) 97.3 (92.4–99.4) 81.2 (56.9–93.4) 86.6 (82.5–89.8) 86 (79.2–91.2)
CI: condence interval, NPV: negative predictive value, PPV: positive predictive value
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDGPET/CT
Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022 71
dIscussIon
An underlying malignant tumor was proven in 30 (21%)
of the 143 patients with suspected PNS. FDG PET/CT
was able to detect the underlying tumor in 24 (16%) of
these patients and was false negative in six patients.
Results from our study demonstrate the ability of FDG
PET/CT to detect underlying tumor with a sensitivity
Figure 1: A 54-year-old woman (patient no. 7 [Table 1]) presenting with h/o tuberculosis with symptoms of progressive pain abdomen and heaviness,
slurred speech, vertigo, tremors, and ataxia. Contrast enhanced computed tomography chest abdomen and pelvis showed cystic adnexal lesion,
fibrotic lung parenchyma changes, and subcentimetric abdominal lymph nodes. Contrast enhanced magnetic resonance imaging brain, serum
electrolytes, and CSF examination were normal. Serum CA-125 was 30 U/mL. Anti-Yo onconeural antibodies were positive. (A: axial and D: coronal)
PET images show FDG focal increased FDG uptake in pelvis; corresponding axial (B and C: blue arrow) and coronal PET/CT and CT images (H and I:
green arrow) show FDG avid ill-defined eccentric nodular mural thickening of the cystic adnexal lesion. PET images (G) also show mildly increased
FDG uptake in the left hypochondrium; corresponding axial PET/CT (H) and CT images (I) show mildly omental stranding and subcentimetric
nodularities (blue arrow). Minimally FDG avid subcentimetric retroperitoneal lymph nodes were also seen. (J) Histopathology from the adnexal lesion
showed nests of tumor cells with vesicular infiltrating the stoma (H&E; 200×). H&E: hematoxylin-eosin
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDG PET/CT
72 72 Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022
Figure 2: A 71-year-old man with h/o smoking (patient no. 8 [Table 1]) had gradual onset of symptoms of chest pain, with SOB, slurred speech,
dysphagia, muscle weakness and wasting, and ataxia, since last 6 months. Contrast enhanced computed tomography thorax showed a heterogenous
right hilar mass, few left lung nodules, right-sided pleural effusion, and few mediastinal lymph nodes. MRI brain and spine were normal. S. electrolytes,
vitamin B12, and thiamine levels and CSF studies were also within normal limits. Anti-Hu antibodies were positive. PET images (A and D) show focal
increased FDG uptake in the right hilar region, mediastinum, and left hemithorax; corresponding axial PET/CT (B and E) and CT images (C and F) show
FDG avid heterogenous soft tissue lesion in the right hilar region (red arrow), some FDG avid mediastinal lymph nodes (blue arrows), a left upper lobe
nodule (green arrow) and mildly expansile lytic rib lesion (yellow arrow). A non-FDG avid right-sided pleural effusion (*) is also seen. PET images (G,
J, and M) show increased focal FDG uptake in abdominal paravertebral regions, left lumbar and iliac regions respectively; corresponding axial PET/
CT (H, K, and N) and CT images (I, L, and O) show FDG avid heterogenous soft tissue lesions of the left kidney (green arrow), right paravertebral
soft tissue (blue arrow), paraver tebral lymph nodes(pink arrow) and ill-defined lesions of spleen and left iliac bone (orange and blue arrows,
respectively). (M) Transbronchial biopsy from the right hilar lesion showed clear cells showing eosinophilic granular cytoplasm with intracytoplasmic
lipid and glycogen, and scant nuclei, arranged in an alveolar and short trabecular pattern- suggestive of metastatic pathology (H&E, 100×). On
immuno histochemistry, CK5, CK7, and TTF1 were negative, whereas CA- IX and AMCAR were positive. Based on the histopathology and immuno
histochemistry, a diagnosis of metastatic clear cell carcinoma of the left kidney was made. H&E: hematoxylin-eosin
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDGPET/CT
Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022 73
Figure 3: A 49-year-old man (patient no. 20 [Table 1]) with symptoms of dysar thria, dysphagia, nystagmus, ataxia, and imbalance for the last
2 months. CT thorax, MRI brain, and onconeural antibodies were negative. Axial PET images (A and D) show focally increase FDG uptake in gastric
and gastrohepatic regions; corresponding axial PET/CT (B and E) and CT images (C and F) show FDG avid mural thickening along the greater curvature
of the body of the stomach (black arrows), few gastrosplenic and perigastric lymph nodes (white arrows) and ill-defined splenic parenchymal lesion
(black arrowhead). PET images (G and J) and corresponding PET/CT (H and K) and CT (I and L) show FDG avid ill-defined minimally lytic and marrow-
based lesions in the dorsal vertebra (green arrow), left scapula (blue arrow), right sacral ala, and bilateral iliac bones (white arrow). (M) Endoscopic
biopsy from the stomach shows large noncleaved cells arranged in discohesive sheets, with a moderate amount of cytoplasm and vesicular nuclei
with prominent nucleoli, involving all layers of the stomach wall (H and E; 100×)
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDG PET/CT
74 74 Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022
and specificity of 80% and 86.7%, respectively. This
finding is similar to some of the previous retrospective
studies, which reported an overall sensitivity between
75% and 100% and specificity ranging between 82% and
91%.[3,23,25,26,33-36] While some of these studies conclude that
FDG PET/CT should only be performed for patients with
well-characterized onconeural antibodies,[37,38] few others
report high sensitivity and specificity of FDG PET/CT
for detecting primary tumor in clinically suspected PNS
patients without positive or well-characterized onconeural
antibodies.[3,16,33] In our study, FDG PET/CT was able
to detect an underlying malignant tumor in 12 (16%)
patients, despite their negative onconeural antibody tests,
hence showing the usefulness of FDG PET/CT to detect
underlying tumor in a significant number of patients with
negative onconeural antibody.
Among patients with negative CT scan, FDG PET/CT
can improve detection rates by approximately 20%.[39] Our
study showed that FDG PET/CT enabled the detection
of underlying primary tumor in nine patients, which
earlier been not detected with previous CT imaging.
By its virtue of combining a whole-body structural and
metabolic imaging in a single examination session, FDG
PET/CT can enable the detection of primary tumor in
a significant number of otherwise negative CT studies.
Further, it also helped in the detection of metachronous
or synchronous tumors in three patients in the present
study. The European Federation of Neurological Sciences
suggests that other imaging modalities (ultrasonography/
CT) should be performed before the use of PET/CT.[5]
However, such an approach could lead to a delay in
diagnosis and appropriate treatment of the underlying
malignancy. Our study shows that FDG PET/CT offers
an incremental value to both onconeural antibodies and
conventional CT in the evaluation of suspected PNS, and
therefore, FDG PET/CT should be initially considered to
rule out any underlying malignanttumor.
False negative FDG PET/CT scans can occur due to a
variety of reasons including that either the tumor was too
small and beyond the scanner resolution limits, or was of
a histopathological type known to be non-FDG avid or
masked by areas of high background physiological FDG
uptake, masking the tumor.[26] In our study, follow-up and
subsequent workup of the initial PET/CT negative cases
identified six (5%) patients with underlying malignant
tumor. This is still lower compared with a reported false
negative FDG PET/CT rate of 9% in the detection of a
malignant tumor.[40] This could be because our average
follow-up time period for PET/CT-negative patients was
4years, whereas some tumors can manifest later, even up
to 8years after the onset of PNS.[41] Hence, a negative PET/
CT does not rule out underlying cancer and depending
on the clinical presentation and degree of suspicion,
follow-up with PET/CT scan or other imaging at 6-month
intervals may be helpful in the detection of previously
occult primary tumor even if onconeural antibody panel
was also negative.[5,26]
One of the recognized drawbacks of FDG PET/CT is
potential for false positive studies for malignant tumor.
Altered FDG uptake resulting from physiological
variations, or FDG uptake in a variety of infective and
inflammatory pathologies[40,42-44] could lead to a false positive
rate of 13%.[40] The present study yielded a false positive
rate of 10%, associated with a variety of nonmalignant
pathologies. While such false positive scans can result in an
increased emotional stress on the patients, eventually they
can also help in diagnosing a significant, inflammatory but
previously undetected pathology, thus leading to better
patients care with reduction in disease-related symptoms
and improvement in patients quality of life.
conclusIons
FDG PET/CT can detect the underlying malignant tumor
in a significant number of patients with suspected PNS,
in both classical as well as nonclassical presentations
irrespective of onconeural antibody status. It has an
incremental value to both onconeural antibodies and
conventional CT scan. In patients with a primary tumor
already detected on CT, FDG PET/CT helps in detecting
metastatic disease and upgrades the disease in a significant
number of patients. In addition, FDG PET/CT also can
help in the detection of a synchronous or metachronous
malignancy in such patients, which may actually be
responsible for current neurological symptoms.
However, FDG PET/CT also has some limitations and can
yield a false positive in some inflammatory conditions and
further investigation may be required in such situations.
Though FDG PET/CT has a high sensitivity for detecting
the tumor of PNS irrespective of onconeural antibody
status, it should be remembered that it can sometimes
still yield a false negative result, and hence, a negative
FDG PET/CT does not always rule out an underlying
malignancy in the setting of a high clinical suspicion and
warrants a careful follow-up or further evaluation with
Chart 1: Comparison between the number of patients with underlying
malignant tumor detected with the three modalities in the present study
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDGPET/CT
Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022 75
other imaging modalities, such as MRI or other tumor-
specific PET tracers, in light of clinical setting.
Limitations of the study
1. This was a retrospective study based on an analysis
of patient records resulting from routine clinical
practice. Referrals from different clinicians were based
on different levels of suspicion. Further, no selection
criteria for risk stratification were used. This might have
reduced the diagnostic performance of FDG PET/CT.
2. Second limitation of the study is in direct head-to-head
comparison of CT scan and FDG PET/CT scans. CT
scans were confined to one or maximum of two body
regions, which were clinically suspected to be the site
of primary tumor, whereas on FDG PET/CT scan,
in some patients, a primary tumor was detected in a
region for which CT had not be performed previously.
This may have led to a relative lower sensitivity of
CT for detection of primary in the present study.
Furthermore, CT and PET/CT scans had have
reported from different government institutes as well
as private diagnostic centers. Hence, some variations
in CT scan acquisition protocols utilized for the
scans and individual reporting variations that might
have occurred were considered and taken careoff by
reviewing the reports and images, and any equivocal or
suspicious reports were reviewed in consultation with
two experienced PET/CT specialists.
3. Though we have used an average follow-up period of
4years, it might still be a limited time frame for ideal
follow-up with respect to clinical detection of the tumor
in initially imaging negative PNS, as in some cases
tumor may manifest even up to 8years after the onset
of PNS.[41] This might have led to reduced reliability of
inferences in terms of false negative results.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
Data availability statement
All relevant clinical and imaging data have been preserved
and are reproducible.
Ethics and quality control statement
This retrospective study was based entirely on existing patient
medical and imaging records, which had been acquired as
a part of routine and standard clinical management and
as such did not require specific ethical approval. However,
permission and approval to assess the patient record
files and scans for reviews as needed were obtained from
respective department HODs and nodal officers. The PET/
CT scans from the two institutes were gotten reviewed as
needed only at that center with no cross-sharing of the
imaging data between both institutes. During the follow-up
and data collection procedure, meticulous care was taken to
organize the data and to trace and retrieve any missing data
otherwise missing from the records.
Declaration of patient consent
The authors certify that they have obtained all appropriate
patient consent forms. In the form, the patient(s) has/have
given his/her/their consent for his/her/their images and
other clinical information to be reported in the journal.
The patients understand that their names and initials will
not be published and due efforts will be made to conceal
their identity, but anonymity cannot be guaranteed.
references
1. Posner JB, Furneaux HM. Paraneoplastic syndromes. Res Publ
Assoc Res Nerv Ment Dis 1990;68:187-219.
2. Darnell RB, Posner JB. Paraneoplastic syndromes involving the
nervous system. N Engl J Med 2003;349:1543-54.
3. HadjivassiliouM, AlderSJ, Van BeekEJ, Hanney MB, LorenzE,
Rao DG, et al. PET scan in clinically suspected paraneoplastic
neurological syndromes: A6-year prospective study in a regional
neuroscience unit. Acta Neurol Scand 2009;119:186-93.
4. HonnoratJ, Antoine J-C. Paraneoplastic neurological syndromes.
Orphanet J Rare Dis 2007;2:22.
5. Titulaer MJ, Soffietti R, Dalmau J, Gilhus NE, Giometto B,
GrausF, et al. Screening for tumors in paraneoplastic syndromes:
Report of an EFNS task force: Screening for tumors in PNS. Eur J
Neurol 2011;18:19-e3.
6. Viaccoz A, Honnorat J. Paraneoplastic neurological syndromes:
General treatment overview. Curr Treat Options Neurol
2013;15:150–68.
7. Keime-GuibertF, GrausF, FleuryA, ReneR, HonnoratJ, BroetP,
DelattreJY: Treatment of paraneoplastic neurological syndromes
with antineuronal antibodies (anti-Hu, anti-Yo) with a combination
of immunoglobulins, cyclophosphamide, and methylprednisolone. J
Neurol Neurosurg Psychiatry 2000;68:479-82.
8. Vernino S, O’Neill BP, Marks RS, O’Fallon JR, Kimmel DW:
Immunomodulatory treatment trial for paraneoplastic neurological
disorders. Neuro Oncol 2004; 6:55-62.
9. ToothakerTB, Rubin M. Paraneoplastic neurological syndromes:
Areview. Neurologist 2009;15:21–33.
10. Darnell RB, Posner JB. Paraneoplastic syndromes involving the
nervous system. N Engl J Med 2003;349:1543–54.
11. Didelot A, Honnorat J. Update on paraneoplastic neurological
syndromes. Curr Opin Oncol 2009;21:566–72.
12. LangB, DaleRC, VincentA. New autoantibody mediated disorders
of the central nervous system. Curr Opin Neurol 2003;16:351–7.
13. GrausF, DelattreJY, AntoineJC, DalmauJ, Giometto B, GrisoldW,
etal. Recommended diagnostic criteria for paraneoplastic neurological
syndromes. J Neurol Neurosurg Psychiatry 2004;75:1135–40.
14. Honnorat J, Cartalat-Carel S, Ricard D, Camdessanche JP,
Carpentier AF, Rogemond V, et al. Onco-neural antibodies and
tumor type determine survival and neurological symptoms in
paraneoplastic neurological syndromes with Hu or CV2/CRMP5
antibodies. J Neurol Neurosurg Psychiatry 2009;80:412–16.
15. Keime-GuibertF, GrausF, FleuryA, RenéR, HonnoratJ, BroetP,
et al. Treatment of paraneoplastic neurological syndromes with
antineuronal antibodies (anti-Hu, anti-Yo) with a combination of
immunoglobulins, cyclophosphamide, and methylprednisolone. J
Neurol Neurosurg Psychiatry 2000;68:479–82.
16. Matsuhisa A, Toriihara A, Kubota K, Makino T, Mizusawa H,
Shibuya H. Utility of F-18 FDG PET/CT in screening for
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]

Gupta, etal.: Value of 18F-FDG PET/CT
76 76 Bengal Journal of Cancer ¦ Volume 2 ¦ Issue 2 ¦ July-December 2022
paraneoplastic neurological syndromes. Clin Nucl Med
2012;37:39–43.
17. Rees JH, Hain SF, Johnson M, Hughes RA, Costa DC, Ell PJ,
et al. The role of F-18 fluoro-2-deoxyglucose-PET scanning in
the diagnosis of paraneo-plastic neurological disorders. Brain
2001;124:2223–31.
18. Lorusso L, Hart IK, Ferrari D, Ngonga GK, Gasparetto C,
Ricevuti G. Autonomic paraneoplastic neurological syndromes.
Autoimmun Rev 2007;6:162–8.
19. Graus F, Vogrig A, Muñiz-Castrillo S, Antoine JC, Desestret V,
Dubey D, et al. Updated diagnostic criteria for paraneoplastic
neurologic syndromes. Neurol Neuroimmunol Neuroinflamm
2021;8:e1014.
20. Dropcho EJ. Immunotherapy for paraneoplastic neurological
disorders. Expert Opin Biol Ther 2005;5:1339–48.
21. Didelot A, Honnorat J. Update on paraneoplastic neurological
syndromes. Curr Opin Oncol 2009;21:566–72.
22. BannasP, WeberC, DerlinT, LambertJ, LeypoldtF, AdamG, etal.
F-18-FDG-PET/CT in the diagnosis of paraneoplastic neurological
syndromes: Aretrospective analysis. Eur Radiol 2010;20:923–30.
23. Schramm N, RomingerA, Schmidt C, MorelliJN, Schmid-
TannwaldC, MeinelFG, etal. Detection of underlying malignancy
in patients with paraneoplastic neurological syndromes: Comparison
of 18F-FDG PET/CT and contrast-enhanced CT. Eur J Nucl Med
Mol Imaging 2013;40:1014-24.
24. Lebech AM, Gaardsting A, Loft A, Graff J, Markova E,
BertelsenAK, etal. Whole-body 18F-FDG PET/CT is superior to
CT as first-line diagnostic imaging in patients referred with serious
nonspecific symptoms or signs of cancer: Arandomized prospective
study of 200 patients. J Nucl Med 2017;58:1058-64.
25. MaskeryMP, HillJ, CainJR, Emsley HCA. The utility of FDG-
PET/CT in clinically suspected paraneoplastic neurological
syndrome: Aliterature review and retrospective case series. Front
Neurol 2017;8:238.
26. BreslerR, Harry WS, ChowDZ, Lim R. 18F-fluorodeoxyglucose
positron emission tomography/computed tomography in the
diagnosis of suspected paraneoplastic syndromes: A retrospective
analysis. World J Nucl Med 2020;19:124-30.
27. McKeon A, Apiwattanakul M, Lachance DH, Lennon VA,
Mandrekar JN, Boeve BF, et al. Positron emission tomography-
computed tomography in paraneoplastic neurologic disorders
systematic analysis and review. Arch Neurol 2010;67:322-9.
28. LeeJR, KimJS, RohJL, LeeJH, BaekJH, ChoKJ, etal. Detection
of occult primary tumors in patients with cervical metastases of
unknown primary tumors: Comparison of (18)F FDG-PET/CT
with contrast-enhanced CT or CT/MR imaging-prospective study.
Radiology 2015;274:764–71.
29. Alfonso A, Redondo M, Rubio T, Del Olmo B, Rodríguez-
Wilhelmi P, García-Velloso MJ, et al. Screening for occult
malignancy with FDG- PET/CT in patients with unprovoked
venous thromboembolism. Int J Cancer 2013;133:2157–64.
30. CacicedoJ, NavarroA, DelHoyoO, Gomez-IturriagaA, AlongiF,
Medina JA, et al. Role of fluorine-18 fluorodeoxyglucose PET/
CT in head and neck oncology: The point of view of the radiation
oncologist. Br J Radiol 2016;89:20160217.
31. Chun AR, Jo HM, Lee SH, ChunHW, Park JM, KimKJ, et al.
Risk of malignancy in thyroid incidentalomas identified by
fluorodeoxyglucose-positron emission tomography. Endocrinol
Metab 2015;27:71–7.
32. TregliaG, TaralliS, SalsanoM, MuoioB, SadeghiR, GiovanellaL.
Prevalence and malignancy risk of focal colorectal incidental uptake
detected by (18)F FDG-PET or PET/CT: Ameta-analysis. Radiol
Oncol 2014;48:99-104.
33. VaidyanathanS, PenningtonC, NgCY, PoonFW, HanS. F-18-FDG
PET-CT in the evaluation of paraneoplastic syndromes: Experience
at a regional oncology centre. Nucl Med Commun 2012;33:
872–80.
34. Kristensen SB, Hess S, Petersen H, Høilund-Carlsen PF. Clinical
value of FDG- PET/CT in suspected paraneoplastic syndromes:
A retrospective analysis of 137 patients. Eur J Nucl Med Mol
Imaging 2015;42:2056–63.
35. Pena Pardo FJ, García Vicente AM, Amo-Salas M, López-
FidalgoJF, GarridoRoblesJA, deAyalaFernándezJÁ, etal. Utility
of 18F-FDG-PET/CT in patients suspected of paraneoplastic
neurological syndrome: Importance of risk classification. Clin
Transl Oncol 2017;19:111-18.
36. VatankuluB, YilmazAksoyS, AsaS, SagerS, SaymanHB, HalacM,
etal. Accuracy of FDG-PET/CT and paraneoplastic antibodies in
diagnosing cancer in paraneoplastic neurological syndromes. Rev
Esp Med Nucl Imagen Mol 2016;35:17–21.
37. Patel RR, Subramaniam RM, Mandrekar JN, Hammack JE,
Lowe VJ, Jett JR. Occult malignancy in patients with suspected
paraneoplastic neurologic syndromes: Value of positron emission
tomography in diagnosis. Mayo Clin Proc 2008;83:917–22.
38. Younes-Mhenni S, Janier MF, Cinotti L, Antoine JC, Tronc F,
CottinV, etal. FDG-PET improves tumor detection in patients with
paraneoplastic neurological syndromes. Brain 2004;127:2331–38.
39. DevineMF, Kothapalli N, ElkhoolyM, Dubey D. Paraneoplastic
neurological syndromes: Clinical presentations and management.
Ther Adv Neurol Disord 2021;14:1756286420985323.
40. AlaviA, GuptaN, AlberiniJL, HickesonM, AdamLE, BhargavaP,
et al. Positron emission tomography imaging in non malignant
thoracic disorders. Semin Nucl Med 2002;32:293-321.
41. Lucchinetti CF, Kimmel DW, Lennon VA. Paraneoplastic and
oncologic profiles of patients seropositive for type 1 antineuronal
nuclear autoantibodies. Neurology 1998;50:652-7
42. Gupta NC, Graeber GM, Bishop HA. Comparative efficacy
of positron emission tomography with fluorodeoxyglucose in
evaluation of small (<1cm), intermediate (1 to 3 cm), and large
(>3 cm) lymph node lesions. Chest 2000;117:773-78.
43. LeeKH, Chung JK. 18 F-FDG positron emission tomography in
the evaluation of infectious and inflammatory diseases. In: Clinical
PET and PET/CT. New York, NY: Springer; 2013. pp.325-43
44. HutomoF, YudistiroR, MulyantoID, BudiawanH. False positive
finding from malignancy-like lesions on FDG PET/CT: Case report
of tuberculosis patients. BMC Med Imaging 2020;20:26.
[Downloaded free from http://www.bengaljcancer.org on Thursday, August 17, 2023, IP: 117.207.54.238]