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Ventilation/perfusion (V/P) single-photon emission computed tomography (SPECT) is recognized as a diagnostic method with potential beyond the diagnosis of pulmonary embolism. V/P SPECT identifies functional impairment in diseases such as heart failure (HF), pneumonia, and chronic obstructive pulmonary disease (COPD). The development of hybrid SPECT...
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Citations
... Three patients were falsely positive in our study, of which one patient showed segmental hyperexpanded oligaemic lung parenchyma with perfusion defects on Q-SPECT/CT. Although perfusion defect in emphysema is uncommon, such findings have been reported and are postulated to be related to vascular changes [39,40]. Cardiac failure can result in upper lobe diversion of 99mTc-MAA which may lead to lower lobar perfusion defects mimicking embolic defects. ...
PurposeTo evaluate the clinical outcome of Q-SPECT/CT in pulmonary thromboembolic disease.Methods
From Jan 2020 to Jan 2021, 30 consecutive patients (M:F = 8:22; median age = 52 year (21–89)) suspected of having acute pulmonary embolism (PE) or chronic thromboembolic pulmonary hypertension (CTEPH) were referred for non-contrasted Q-SPECT/CT. All patients were COVID-19 PCR negative. MSKCC Q-SPECT/CT and/or PISAPED criteria were used to determine the presence of thromboembolic disease in Q-SPECT/CT. Final diagnosis was made based on composite reference standards that included at least 2-month clinical cardiorespiratory assessment and follow-up imaging.ResultsQ-SPECT/CT was positive in 19 patients: indeterminate in 1 and 10 were negative. Three false positive cases were observed during follow-up. Of the remaining 16 true positives, all patients’ cardiorespiratory symptom were improved or stabilised after treatment with anticoagulants. The overall sensitivity, specificity, PPV, NPV and accuracy of Q-SPECT/CT were 100% (95% CI, 79.41–100%), 78.57% (95% CI, 49.20–95.34%), 84.21% (95% CI, 66.41–93.57%), 100% and 90.00% (95% CI, 73.47–97.89%) respectively.Conclusions
In the current COVID-19 pandemic, Q-SPECT/CT can be an alternative modality to detect pulmonary thromboembolic disease. Normal Q-SPECT/CT excludes pulmonary thromboembolic disease with high degree of certainty. However, false positive has been observed.
... The combination of nuclear medicine (NM) apparatus (Singlephoton emission computed tomography (SPECT) and computed tomography (CT) incorporates functional and morphologic human body findings, which results in improvement of patient diagnosis with high specificity and sensitivity beyond 90% (Jögi et al., 2015;Hirschmann et al., 2015). Due to real advantages, SPECT/CT is widely used to diagnose a wide range of pathological conditions. ...
Staff occupational radiation exposure is limited to 20 mSv annually to preclude tissue reaction and lower risk of cancer effect. Staff occupational exposure arises during the preparation, injection, and scanning of the patients. Recent studies reported that nuclear medicine personnel might exceed the annual dose limit in high workload and poor radiation protection circumstances. Therefore, an accurate estimation of the annual dose limit is recommended. The goal of this research is to calculate the cumulative external effective dose (mSv) per year for nuclear medicine physicians, technologists, and nurses at SPECT/CT department. A total of 15 staff worked in the nuclear medicine department at King Saud Medical City (KSMC), Riyadh, Saudi Arabia were evaluated for the last six years. 99mTc is used more frequently for most of the patients. The procedures include renal, cardiac scintigraphy procedures. Staff dose was quantified using calibrated thermoluminecnt dosimeters (TLD-100) with an automatic TLD reader (Harshaw 6600). Exposure to ionizing radiation was evaluated in terms of deep doses (Hp(10) were evaluated. The overall average and standard deviation of the external doses for nuclear medicine physicians, technologists' and nurses were 1.8 ± 0.7, 1.9 ± 0.6, 2.0 ± 0.9, 2.2 ± 0.8, 6.0 ± 2.8, and 3.6 ± 1.3 for the years 2015,2016,2017,2018,2019, and 2020, respectively. Technologists and nurses received higher doses of compared to the nuclear medicine physicians. Technologists and nurses involved in radionuclide preparation, patients' injection, and image acquisition. Staff annual exposure is below the annual dose limits; however, this external dose is considered high compared to the current workload.
... V/Q SPECT/CT imaging gives the opportunity to evaluate both perfusion and lung anatomy and allows precise mapping of the ventilation and perfusion defects to the corresponding segments of the lungs [14]. The additional value of V/Q SPECT/CT in patients with chronic obstructive pulmonary disease (COPD) has been reported in the literature and further studies are needed to investigate the role of V/Q SPECT/ CT in various patient categories such as in patients with possible CTEPH [15]. ...
Objectives:
We aimed to perform a comparison between V/Q single-photon emission computed tomography/computed tomography (SPECT/CT) and V/Q Quotient single-photon emission computerized tomography (SPECT) in the detection of chronic thromboembolic pulmonary hypertension (CTEPH) and in depicting the extent of the disease on per-segment basis in patients with CTEPH.
Methods:
Between January 2015 and November 2019, a total of 412 patients with pulmonary hypertension secondary to CTEPH at the preoperative assessment underwent pulmonary endarterectomy (PEA), of whom 92 consecutive patients with their V/Q SPECT/CT scans have been performed in our institution prior to PEA were included in this study. Histopathological findings and post-PEA fully resected surgical specimens were used as the reference standard.
Results:
On a per-patient basis analysis, V/Q SPECT/CT and V/Q Quotient SPECT both revealed CTEPH in the same 85 of the 92 patients (κ = 1) with a detection rate of 92.4%. In six of these patients, chronic thromboembolic disease could not be reported on both of these two methods due to extensive 'matched' V/Q defects. On a per-segment basis analysis, V/Q SPECT/CT and V/Q Quotient SPECT showed a sensitivity of 75.8 and 73.1%, respectively. Correlation analysis results showed a significant correlation (κ = 0.933) between these two methods on a per-segment basis analysis.
Conclusion:
In the light of histopathological findings and post-PEA surgical specimen examinations, the results of the present study indicated that both V/Q SPECT/CT and V/Q Quotient SPECT showed relatively high efficacy for the detection of CTEPH on per-patient and per-segment bases with an excellent agreement.
... Further studies of V/P SPECT/CT to define its value according to good clinical practice in various categories of patients seem merited. In patients with COPD, the added value of V/P SPECT/ CT has been validated [93]. ...
... A general unevenness of ventilation typical for COPD has been observed in V/P SPECT in patients investigated for PE [68,120,146]. Perfusion is usually less affected, which leads to so-called reversed mismatch [62,93,119]. The degree of ventilation defects reflects varying degrees of obstruction with COPD. Figure 7 presents cases with different degrees of COPD [62,68,120,[147][148][149]: ...
These guidelines update the previous EANM 2009 guidelines on the diagnosis of pulmonary embolism (PE). Relevant new aspects are related to (a) quantification of PE and other ventilation/perfusion defects; (b) follow-up of patients with PE; (c) chronic PE; and (d) description of additional pulmonary physiological changes leading to diagnoses of left ventricular heart failure (HF), chronic obstructive pulmonary disease (COPD) and pneumonia. The diagnosis of PE should be reported when a mismatch of one segment or two subsegments is found. For ventilation, Technegas or krypton gas is preferred over diethylene triamine pentaacetic acid (DTPA) in patients with COPD. Tomographic imaging with V/PSPECT has higher sensitivity and specificity for PE compared with planar imaging. Absence of contraindications makes V/PSPECT an essential method for the diagnosis of PE. When V/PSPECT is combined with a low-dose CT, the specificity of the test can be further improved, especially in patients with other lung diseases. Pitfalls in V/PSPECT interpretation are discussed. In conclusion, V/PSPECT is strongly recommended as it accurately establishes the diagnosis of PE even in the presence of diseases like COPD, HF and pneumonia and has no contraindications.
... Lung parenchymal attenuation has been correlated with emphysema and pulmonary function test (PFT) measurements. Ventilation/ perfusion single-photon emission CT (V/Q-SPECT/CT) has also been used to assess ventilation and perfusion in COPD [6][7][8][9][10]. In clinical practice, V/Q-SPECT has been shown to be a useful imaging technique in the detection of severe ventilation defects in patients with COPD [11]. ...
Purpose
To derive lobar ventilation in patients with chronic obstructive pulmonary disease (COPD) using a rapid time-series hyperpolarized xenon-129 (HPX) magnetic resonance imaging (MRI) technique and compare this to ventilation/perfusion single-photon emission computed tomography (V/Q-SPECT), correlating the results with high-resolution computed tomography (CT) and pulmonary function tests (PFTs).
Materials and methods
Twelve COPD subjects (GOLD stages I–IV) participated in this study and underwent HPX-MRI, V/Q-SPECT/CT, high-resolution CT, and PFTs. HPX-MRI was performed using a novel time-series spiral k-space sampling approach. Relative percentage ventilations were calculated for individual lobe for comparison to the relative SPECT lobar ventilation and perfusion. The absolute HPX-MRI percentage ventilation in each lobe was compared to the absolute CT percentage emphysema score calculated using a signal threshold method. Pearson’s correlation and linear regression tests were performed to compare each imaging modality.
Results
Strong correlations were found between the relative lobar percentage ventilation with HPX-MRI and percentage ventilation SPECT (r = 0.644; p < 0.001) and percentage perfusion SPECT (r = 0.767; p < 0.001). The absolute CT percentage emphysema and HPX percentage ventilation correlation was also statistically significant (r = 0.695, p < 0.001). The whole lung HPX percentage ventilation correlated with the PFT measurements (FEV1 with r = − 0.886, p < 0.001*, and FEV1/FVC with r = − 0.861, p < 0.001*) better than the whole lung CT percentage emphysema score (FEV1 with r = − 0.635, p = 0.027; and FEV1/FVC with r = − 0.652, p = 0.021).
Conclusion
Lobar ventilation with HPX-MRI showed a strong correlation with lobar ventilation and perfusion measurements derived from SPECT/CT, and is better than the emphysema score obtained with high-resolution CT.
Key Points
• The ventilation hyperpolarized xenon-129 MRI correlates well with ventilation and perfusion with SPECT/CT with the advantage of higher temporal and spatial resolution.
• The hyperpolarized xenon-129 MRI correlates with the PFT measurements better than the high-resolution CT with the advantage of avoiding the use of ionizing radiation.
... 31 In this context, adding a low-dose CT to a V/Q SPECT protocol is particularly useful. This approach was evaluated prospectively in stable COPD patients and healthy smokers, 32 in which the low-dose CT was found to make the V/Q SPECT interpretation more certain in 10% of the cases, while also providing additional diagnoses such as lung cancer, emphysema, pulmonary embolism, and heart failure, in the majority of cases. Hence, V/Q SPECT/CT has an added value compared to performing V/Q SPECT in COPD patients. ...
Ventilation-perfusion scintigraphy is a functional imaging biomarker that has the potential of captivating the heterogeneity of chronic obstructive pulmonary disease (COPD). It specifically images the distribution of ventilation and perfusion within the lungs, which is a critical pathophysiological component of COPD. The extent of ventilation defects and ventilation inhomogeneity, as well as the ventilation-perfusion ratio distribution thus correlate with severity of disease. Furthermore, specific scintigraphic patterns, such as the “stripe sign” may detect centrilobular emphysematous lesions with a higher sensitivity than other imaging techniques. Although ventilation-perfusion scintigraphy may conceivably detect COPD before any specific changes can be detected by spirometry or high-resolution CT, it is currently mostly used in the workup of lung volume reduction treatment, and for diagnosing various complications and comorbidities of COPD when combined with low-dose CT.
... [2] Another potential advantage of adding ldCT to V/Q SPECT over V/Q SPECT alone is the possibility of providing alternative diagnosis (e.g., pneumothorax, pneumonia) in patients suspected with PE which has been reported as an advantage of CTPA, or the possibility of providing incidental but clinically relevant findings (e.g., breast tumor). [9,10] Moreover, some alternative diagnoses to PE, such as IMH, are life-threatening emergencies that need to be detected as early as possible. ...
Rationale:
Ventilation/perfusion (V/Q) single-photon-emission computed tomography (SPECT) has arisen as an alternative to computed tomography pulmonary angiography (CTPA) in patients with pulmonary embolism (PE) suspicion. The addition of low dose CT (ldCT) to V/Q SPECT improves the specificity of the test, allowing for potential alternative diagnosis.
Patient concerns and diagnosis:
Here we presented a case of an aortic intramural hematoma (IMH) diagnosed on the ldCT portion of V/Q SPECT combined with CT. A 74-year-old man suffering from sudden-onset chest pain was referred to our nuclear medicine department for PE suspicion.
Intervention and outcome:
A V/Q SPECT combined with nonenhanced ldCT ruled out PE diagnosis. Nevertheless, ldCT revealed high attenuation aortic wall thickening suggestive of aortic IMH. Chest CT angiography showed mild dilatation and circumferential thickening of aortic wall confirming Stanford type A IMH involving the entire ascending aorta.
Lesson:
This case illustrates the potential usefulness of combining ldCT to V/Q SPECT in providing alternative diagnosis in suspected PE patients.
... The next step in the evolution of nuclear imaging is the integration both nuclear studies and low-dose CT. This approach offers several potential benefits, among which is an increase in specificity compared to a stand-alone V/Q SPECT due to the ability of the CT to demonstrate pathological findings that can mimic PE related perfusion defects such as areas of emphysema in patients with COPD or pneumonia, with only a small increase in radiation from the low-dose CT [72][73][74] (Fig. 4). A study that compared the diagnostic capabilities of SPECT-CT and CTPA demonstrated higher diagnostic accuracy, leading the authors to recommend using SPECT-CT as the potential modality of choice for the evaluation of PE [75]. ...
Purpose of review:
CT angiography has become the gold standard for evaluation of suspected pulmonary embolism; however, continuous evolution in radiology has led to new imaging approaches that offer improved options for detection and characterization of pulmonary embolism while exposing patients to lower contrast and radiation dose. The purpose of this review is to summarize state of the art imaging approaches for the evaluation of pulmonary embolism, focusing on technical innovations in this field.
Recent findings:
The introduction of dual-energy CT has resulted in the ability to add functional and prognostic information beyond the morphologic assessment of the pulmonary arteries and potentially offer improved image quality without additional radiation burden. New approaches and strategies in CT scanning have resulted in decreased radiation exposure as well as a significant decrease in contrast material used without decreasing the sensitivity for detection of pulmonary embolism. Continuous developments and improvements in MR angiography techniques offer a valuable and efficient option for certain patient populations without the risk of radiation exposure. Improvements in the technical success rate and reliability of this modality will mean more widespread use in the future. Moving beyond planar ventilation/perfusion (V/Q) scintigraphy, nuclear imaging offers several new approaches, including the use of single photon emission computed tomography (SPECT) and SPECT/CT resulting in superior diagnostic performance and a decrease in nondiagnostic studies, potentially surpassing the diagnostic capabilities of computed tomography pulmonary angiography. Ongoing research in the use of V/Q PET/CT demonstrates superior temporal and spatial resolution and quantitative capabilities compared to SPECT-CT; this modality will likely play an increasing role in the detection and characterization of pulmonary embolism. The field of pulmonary embolism imaging has demonstrated continuous evolution in both development of novel techniques and improvement in current technologies, resulting in better detection, decreased radiation exposure, and enhanced functional information beyond morphologic characterization of the pulmonary vasculature.
... Segmentation is necessary to make objective measurements of lung function and characterization of pathophysiological changes. Previous work has been focused on semiquantitative analysis [7][8][9][10][11]. User-independent segmentation of the lung is likely to be an essential further improvement to these techniques, to facilitate implementation on the larger scale for routine use. ...
Objective:
Image segmentation is an essential step in quantifying the extent of reduced or absent lung function. The aim of this study is to develop and validate a new tool for automatic segmentation of lungs in ventilation and perfusion SPECT images and compare automatic and manual SPECT lung segmentations with reference computed tomography (CT) volumes.
Methods:
A total of 77 subjects (69 patients with obstructive lung disease, and 8 subjects without apparent perfusion of ventilation loss) performed low-dose CT followed by ventilation/perfusion (V/P) SPECT examination in a hybrid gamma camera system. In the training phase, lung shapes from the 57 anatomical low-dose CT images were used to construct two active shape models (right lung and left lung) which were then used for image segmentation. The algorithm was validated in 20 patients, comparing its results to reference delineation of corresponding CT images, and by comparing automatic segmentation to manual delineations in SPECT images.
Results:
The Dice coefficient between automatic SPECT delineations and manual SPECT delineations were 0.83 ± 0.04% for the right and 0.82 ± 0.05% for the left lung. There was statistically significant difference between reference volumes from CT and automatic delineations for the right (R = 0.53, p = 0.02) and left lung (R = 0.69, p < 0.001) in SPECT. There were similar observations when comparing reference volumes from CT and manual delineations in SPECT images, left lung (bias was - 10 ± 491, R = 0.60, p = 0.005) right lung (bias 36 ± 524 ml, R = 0.62, p = 0.004).
Conclusion:
Automated segmentation on SPECT images are on par with manual segmentation on SPECT images. Relative large volumetric differences between manual delineations of functional SPECT images and anatomical CT images confirms that lung segmentation of functional SPECT images is a challenging task. The current algorithm is a first step towards automatic quantification of wide range of measurements.
... Jogi., et ai. found that even so called "healthy" smokers show various grades of airway obstruction by V/P SPECT, although spirometry did not show any sign of airway obstruction or limitätion in expiratory flow, (FEV1) [13]. VVoodruff and colleagues showed that current and former smokers, with a normal spirometry have chronic clinically significant respiratory symptoms, exacerbation activity, declined exercise tolerance, and imaging evidence of inflammation in the small airways [14], Jobse., et ai. ...
Background: V/P SPECT is today primarily used to diagnose and follow-up pulmonary embolism (PE). The clinical diagnosis of pulmonary
embolism (PE) in chronic obstructive pulmonary disease (COPD) patients is considered challenging because the symptoms
ofboth PE and COPD are non-specific and quite alike.
Aim: The first aim of the study was to evaluate how frequent COPD is among patients with suspected PE usingV/P SPECT. The second
aim was to investigate the ability of V/P SPECT to diagnose PE in patients who have simultaneously airway obstruction.
Methods and Materials: 1274 consecutive patients clinically suspected for PE were retrospectively investigated for PE and signs of
obstruction with V/P SPECT. Ali patients with signs of obstruction were classified into 3 groups according to the grade of severity of
obstruction mentioned in the final reports.
Results: PE was diagnosed in 353 (28%) patients. Mild, moderate or severe airway obstruction were shown in 697 patients (55%).
Among patients with PE, 90 patients (25%) were also diagnosed as obstructive. Ali examinations in patients with both PE and COPD
were diagnostic.
Conclusion: Mild, moderate or severe airway obstruction typical for COPD is frequent among patients with suspected PE, and more
than half of the patients referred with clinical suspicion of PE have signs of COPD. With V/P SPECT it is possible to diagnose both
conditions fast and accurately. COPD is not a contraindication to use pulmonary ventilation/perfusion tomography for PE diagnosis
even in the most severe grade of COPD.
Keyvvords: V/P SPECT; COPD; Pulmonary Embolism (PE)
