Stefan Müller

Lucerne University of Applied Sciences and Arts | HSLU · Center of Construction Engineering (KI)

Simple Summary Patients with metastasized, castration-resistant prostate cancer can be treated locally with radioactive radium-223, which usually comprises six cycles. We wanted to know whether this treatment affects immune function. We performed cell culture experiments with white blood cells from the patients and added components of microorganism...

Transarterial chemoembolization (TACE) is currently the standard of care in patients with unresectable hepatocellular carcinoma (HCC), and selective internal radionuclide therapy (SIRT) with 90Y microspheres is mainly used as an alternative modality in patients considered poor candidates for TACE. Treatment with sorafenib is the recommended option...

Simple Summary To treat malignant liver tumors, the liver can be irradiated locally with the injection of radioactive microparticles, by a therapy called selective internal radiotherapy. We could previously show that this treatment is correlated with an impaired immune function of white blood cells. As the liver is a well-perfused organ, we assume...

Background [ ¹⁸ F]Fluoro-deoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is the standard imaging procedure in diffuse large B-cell lymphoma (DLBCL). Disease presentation, FDG-PET/CT performance, and outcome may be influenced by germline single nucleotide polymorphisms (SNP) in genes regulating glucose uptake. Methods C...

Background: Surgical resection is considered to be of purely diagnostic value in aggressive lymphoma. Evidence for an impact on outcome is scant and restricted to retrospective observations. Methods: In the "Positron Emission Tomography-guided Therapy of Aggressive non-Hodgkin Lymphomas" (PETAL) trial, patients with a negative baseline positron...

The value of interim 18F-fluorodeoxyglucose positron emission tomography (iPET) guided treatment decisions in patients with diffuse large B-cell lymphoma (DLBCL) has been the subject of much debate. This investigation focuses on a comparison of the Deauville score and the deltaSUVmax (ΔSUVmax) approach - two methods to assess early metabolic respon...

The prospective randomized Positron Emission Tomography (PET)‐Guided Therapy of Aggressive Non‐Hodgkin Lymphomas (PETAL) trial was designed to test the ability of interim PET (iPET) to direct therapy. As reported previously, outcome remained unaffected by iPET‐based treatment changes. In this subgroup analysis, we studied the prognostic value of ba...

T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL) is a rare aggressive lymphoma characterized by a paucity of neoplastic B-cells and a majority of reactive T-cells with or without histiocytes. In the ‘Positron Emission Tomography-Guided Therapy of Aggressive Non-Hodgkin Lymphomas’ trial (clinicaltrials.gov NCT00554164; EudraCT 2006-001641-33),...

Purpose: This pilot study aimed to determine interobserver reliability and ease of use of three workflows for measuring metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in diffuse large B cell lymphoma (DLBCL). Procedures: Twelve baseline [18F]FDG PET/CT scans from DLBCL patients with wide variation in number and size of involved o...

Total metabolic tumor volume (TMTV) was measured in 510 patients with DLBCL participating in the PETAL trial. The present data provide information about the prognostic impact of total metabolic tumor volume using the fixed standardized uptake value (SUV4) instead of the relative SUV41max thresholding method. A Bland-Altman plot was created to compa...

Background: Valid prognostic tools are needed to guide risk-adjusted treatment approaches in patients with diffuse large B-cell lymphoma (DLBCL). Methods: We assessed total metabolic tumor volume (TMTV) and standardized uptake value (SUV)-based interim positron emission tomography (iPET) response in 510 patients with DLBCL participating in the p...

In patients with non-resectable hepatic malignancies selective internal radiotherapy (SIRT) with yttrium-90 is an effective therapy. However, previous data indicate that SIRT leads to impaired immune function. The aim of the current study was to determine the extent of DNA lesions in peripheral blood mononuclear cells of SIRT patients and to correl...

Standard first-line treatment of aggressive B cell lymphoma comprises six or eight cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) plus eight doses of rituximab (R). Whether adding two doses of rituximab to six cycles of R-CHOP is of therapeutic benefit has not been systematically investigated. The Positron Emission Tomo...

Introduction: Treatment results in diffuse large B-cell lymphoma (DLBCL) are heterogeneous. Established risk models like the International Prognostic Index (IPI) and molecular lymphoma features such as MYC translocations and the cell of origin (COO) subtype are prognostic of outcome. A positive iPET scan after 2 cycles of rituximab, cyclophosphamid...

Introduction: The recently published randomized PETAL trial (JCO 36:2024, 2018) aimed at improving outcome of aggressive non-Hodgkin lymphomas by changing therapy based on the response to the first 2 cycles of standard (R-)CHOP as assessed by interim PET (iPET). Outcome remained unaffected by treatment changes, which provided an opportunity to use...

Purpose Interim positron emission tomography (PET) using the tracer, [ ¹⁸ F]fluorodeoxyglucose, may predict outcomes in patients with aggressive non-Hodgkin lymphomas. We assessed whether PET can guide therapy in patients who are treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP). Patients and Methods Newly diagnosed pa...

The purpose of our study was to assess the immune function of patients with inoperable hepatic malignancies after treatment with selective internal radiotherapy (SIRT) and to identify possible correlations with clinical parameters. In 25 patients receiving SIRT lymphocyte proliferation and the production of pro- and anti-inflammatory cytokines (int...

Zusammenfassung These guidelines aim to support medical personnel and physicians working in oncology in selecting appropriate patients, in treatment planning, preparation and implementation of SIRT for the treatment of primary and secondary liver malignancies. The focus lies on the requirements in the treatment center with regard to staffing, techn...

Background: Locoregional bridging treatments are commonly applied in hepatocellular carcinoma (HCC) patients prior to liver transplantation to prevent tumor progression during waiting time. It remains unknown whether pre-transplant radioembolization treatment may increase the prevalence of hepatic artery and biliary complications post-transplant....

Background Changes in glucose and energy metabolism contribute to the altered phenotype of cancer cells and are the basis for positron emission tomography with ¹⁸F-fluoro-2-deoxy-d-glucose (FDG) to visualize tumors in vivo. The molecular background of the enhanced glucose uptake and its regulation in lymphoma cells is not fully clarified and may pr...

Introduction Radioembolization for the treatment of hepatocellular carcinoma (HCC) induces liver volume changes referred to as “atrophy-hypertrophy complex”. The aim of this study was to investigate lobar liver volume changes after unilateral radioembolization and to search for factors associated with hypertrophy of the untreated lobe. Materials a...

Raw data of patient baseline characteristics and liver volumetry. (XLSX)

Background Bridging treatments are employed in liver transplant waitlist patients with hepatocellular carcinoma (HCC) because of the risk of tumor progression during the waiting time. Radioembolization is mostly employed in the control of large or multifocal HCCs when other locoregional treatment modalities cannot be applied because of the number o...

PurposeTherapy with the alpha-emitter radium-223 chloride (223Ra) is an innovative therapeutic option in patients with metastasized, castration-resistant prostate cancer. However, radiotherapy can lead to hematopoietic toxicity. The aim of this study was to determine if 223Ra therapy induces an impairment of cellular antimicrobial immune responses....

Worldwide hepatocellular carcinoma remains one of the leading causes of cancer-related death, associated with a poor prognosis due to late diagnosis in the majority of cases. Physicians at care are frequently confronted with patients who are ineligible for curative treatment such as liver resection, transplantation or radiofrequency ablation. Besid...

Introduction: The PETAL trial is a multicenter randomized controlled study for patients with aggressive lymphomas of diverse histologies (EudraCT 2006-001641-33, NCT00554164). In the study population as a whole interim PET (iPET) reliably predicted time to treatment failure (TTTF) and overall survival (OS). Interim PET-based treatment changes, howe...

Introduction: The PETAL trial is a multicenter randomized controlled study for patients with aggressive lymphomas of diverse histologies (EudraCT 2006-001641-33, NCT00554164). In the study population as a whole interim PET (iPET) reliably predicted time to treatment failure (TTTF) and overall survival (OS). Interim PET-based treatment changes, howe...

Neuroectodermal tumours are characterized by aberrant processing of disialogangliosides concomitant with high expression of GD2 or GD3 on cell surfaces. Antibodies targeting GD2 are already in clinical use for therapy of neuroblastoma, a solid tumour of early childhood. Here, we set out to identify peptides with high affinity to human disialogangli...

Background Patients with dedifferentiated and anaplastic thyroid carcinomas that do not take up radioiodine are resistant to chemotherapeutic treatment and external irradiation and thus are difficult to treat. Direct induction of apoptosis is a promising approach in these apoptosis-resistant tumor cells. The BH3 mimetic ABT-737 belongs to a new cla...

Introduction: We recently reported the first results of the large multicenter phase III PETAL trial (EudraCT 2006-001641-33, NCT00554164) showing that 18-fluorodeoxyglucose interim PET (iPET) performed after two cycles of chemotherapy is highly predictive of clinical outcome in patients with aggressive lymphomas. Here, the study`s biobank was utili...

Patients with dedifferentiated or anaplastic thyroid carcinomas currently lack appropriate treatment options. Kinase inhibitors are among the most promising new agents as alternative strategies. The BRAF- and multi-kinase inhibitor, sorafenib, has already shown antitumor effects in thyroid carcinoma patients in a phase III clinical trial. In this s...

Selective Internal Radiation Therapy (SIRT) with 90yttrium (Y-90) is an increasingly used therapeutic option for unresectable liver malignancies. Nontarget embolization of extrahepatic tissue secondary to vascular shunting can lead to SIRT associated complications. Our aim was to assess whether extrahepatic shunts can reliably be diagnosed based on...

Recent decades have seen a rise in the incidence of well-differentiated (mainly papillary) thyroid carcinoma around the world. In Germany, the age-adjusted incidence of well-differentiated thyroid carcinoma in 2010 was 3.5 per 100 000 men and 8.7 per 100 000 women per year. This review is based on randomized, controlled trials and multicenter trial...

The radiolabeled somatostatin analogue, yttrium-90 DOTA-D-Phe(1)-Tyr(3)-octreotide (DOTATOC), is currently applied to treat advanced somatostatin receptor-positive tumors, e.g., neuroendocrine tumors of the pancreas, lung or gut. However, effects of this treatment on antimicrobial immune responses are not yet defined. In 20 patients treated with DO...

Introduction: The predictive value of 18-fluorodeoxyglucose PET performed after a few cycles of chemotherapy has been questioned in aggressive lymphomas. Inconsistent study results, however, may be due to procedural differences rather than an inability of the method to predict outcome. Whether changing treatment in pts. with an unfavorable interim...

Selective internal radiation therapy (SIRT) using 90-yttrium is a local therapy for unresectable liver malignancies. Non-targeted 90-yttrium diversion via a patent hepatic falciform artery (HFA) is seen as risk for periprocedural complications. Therefore, this study aimed to evaluate the impact of a patent HFA on SIRT. 606 patients with SIRT betwee...

Background Transarterial chemoembolization (TACE) is one of the standard treatments recommended for intermediate stage hepatocellular carcinoma (HCC). At the same time, only little is known about the use of radioembolization with Yttrium-90 microspheres (TARE Y-90) for this subset of patients.AimsTo perform comparative analysis between both locoreg...

The current prognostic model to estimate the survival in hepatocellular carcinoma (HCC) patients treated with transarterial hepatic selective internal radiotherapy (SIRT) is not fully characterized. The aim of this study was to establish a new scoring model including assessment of both tumor responses and therapy-induced systemic changes in HCC pat...

In this study, Response Evaluation Criteria in Solid Tumors (RECIST), modified RECIST (mRECIST), Choi and modified Choi criteria were compared to determine which method is optimal for response evaluation in hepatocellular carcinoma (HCC) patients treated with transarterial radioembolization (TARE) with yttrium-90 microspheres. Responses were evalua...

Cabozantinib, a tyrosine kinase inhibitor (TKI) of hepatocyte growth factor receptor (MET), vascular endothelial growth factor receptor 2, and rearranged during transfection (RET), demonstrated clinical activity in patients with medullary thyroid cancer (MTC) in phase I. We conducted a double-blind, phase III trial comparing cabozantinib with place...

Purpose: The authors have previously reported the advantages of high-sensitivity single-photon emission computed tomography (SPECT) systems for imaging structures located deep inside the brain. DaTscan (Isoflupane I-123) is a dopamine transporter (DaT) imaging agent that has shown potential for early detection of Parkinson disease (PD), as well as...

PURPOSE Radioembolization (RE) using the beta emitter 90yttrium (Y-90) is an emerging therapy option for unresectable liver malignancies. A complication of RE may represent the nontarget embolization of extrahepatic tissue, particularly the GI tract. We aimed to assess whether extrahepatic shunts can be reliably diagnosed based on hepatic digital s...

PURPOSE Selective-Internal-Radiation-Therapy (SIRT) with Yttrium-90 microspheres is an emerging therapy for patients with advanced stage liver tumors. Aim of this study was to evaluate a new technique based on Ga-68 human serum albumin (HSA) PET in order to assess the distribution of microspheres. METHOD AND MATERIALS Nine patients with hepatic ma...

Purpose: Selective internal radiotherapy (SIRT) with the beta emitter yttrium-90 (Y90) is a rapidly developing therapy option for unresectable liver malignancies. Nontarget irradiation of the gallbladder is a complication of SIRT. Thus, we aimed to assess different strategies to avoid infusion of Y90 into the cystic artery (CA). Methods: After h...

Sorafenib, a protein kinase inhibitor, is a systemic drug that has been licensed for the treatment of hepatocellular carcinoma (HCC). This retrospective study assessed whether the administration of sorafenib can result in a reduction of the hepatopulmonary shunt (HPS) before selective internal radiation therapy (SIRT). After exclusion from SIRT bec...

5508 Background: MTC arises from parafollicular cells of the thyroid gland, accounts for 5-8% of thyroid cancers and represents an unmet medical need. Cabozantinib (cabo) is an oral inhibitor of MET, VEGFR2, and RET. We conducted a phase III study of cabo vs placebo (P) in pts with progressive, unresectable, locally advanced or metastatic MTC. Meth...

PURPOSE Radioembolization (RE) using the beta emitter 90 Yttrium is an emerging therapy option for unresectable liver malignancies. However, a high hepatopulmonary shunt (i.e. due to tumorous AV-fistulae) may represent a contraindication for RE. Sorafenib, a protein kinase inhibitor, is a systemic drug that has been approved for the treatment of ad...

Bone scintigraphy is the standard procedure for the detection of bone metastases in breast cancer patients. FDG-PET/CT has been reported to be a sensitive tool for tumor staging in different malignant diseases. However, its accuracy for the detection of bone metastases has not been compared to bone scintigraphy. To compare whole-body FDG-PET/CT and...

We have developed a new method of compensating for effects of partial volume and spillover in dual-modality imaging. The approach requires segmentation of just a few tissue types within a small volume-of-interest (VOI) surrounding a lesion; the algorithm estimates simultaneously, from projection data, the activity concentration within each segmente...

Unlabelled: Radioembolization has been demonstrated to allow locoregional therapy of patients with hepatocellular carcinoma not eligible for transarterial chemoembolization or other local therapies. The aim of this study was to validate evidence of the safety and efficacy of this treatment in a European sample of patients with advanced hepatocellu...

PURPOSE Patients with differentiated thyroid cancer usually are investigated by a post-treatment 131-I-scintigraphy to detect residual locoregional disease as well as metastases. A lack of anatomical landmarks can complicate the evaluation of scintigraphic images. The aim of this study was to evaluate whether a post-treatment low-dose 131-I-SPECT/C...

2695 Poster Board II-671 Introduction Positron emission tomography (PET) performed after a few cycles of chemotherapy (interim-PET) in aggressive lymphomas correlates with long-term outcome: While the majority of patients with a negative interim-PET scan enjoy long-lasting remissions, patients with persistent pathological glucose uptake almost inv...

In aggressive non-Hodgkin lymphomas, the result of positron emission tomography (PET) with [18F]fluorodeoxyglucose performed after a few cycles of chemotherapy has been shown to correlate with long-term treatment outcome. The PETAL trial investigates whether a change in treatment protocol may improve the outcome of patients with a positive scan aft...

There may be many reasons for patients to decline radionuclide therapy. Some are understandable to us who are used to working professionally with radioactive materials, others, especially those related to fear of radiation, seem completely alien or totally absurd. This is not new: since the end of the 1970s it has been known from the studies of Slo...

We assess the attitude of patients with thyroid disease towards radiation and radioactivity before and after radioiodine therapy by means of a cultural-anthropological approach. We evaluate in patient interviews how their subjective attitude towards radioactivity as an abstract term and towards radioactivity in the medical context on the basis of t...

The osteoblastic response (OR) phenomenon as a healing reaction during effective chemotherapy-defined by the appearance of new osteoblastic bone lesions while disease response in other tumor sites was well documented-has previously been described for breast and prostate cancer. The purpose of this study was to investigate this phenomenon that could...

MR-based attenuation correction (AC) will become an integral part of combined PET/MR systems. Here, we propose a toolbox to validate MR-AC of clinical PET/MRI data sets. Torso scans of ten patients were acquired on a combined PET/CT and on a 1.5-T MRI system. MR-based attenuation data were derived from the CT following MR-CT image co-registration a...

The influence of various geometric factors on I uptake measurements for solitary thyroid nodule was systematically investigated to derive an approach, based on routinely performed ultrasound examinations, to correct for the effect of geometric variations. The influence of size, shape, and position of a thyroid nodule, neck-to-detector distance and...

Aim: Combined whole-body (WB) PET/CT imaging provides better overall co-registration compared to separate CT and PET. However, in clinical routine local PET-CT mis-registration cannot be avoided. Thus, the reconstructed PET tracer distribution may be biased when using the misaligned CT transmission data for CT-based attenuation correction (CT-AC)....

This study assessed the ability of visual and quantitative 124-iodine positron emission tomography ((124)I PET) data to detect disseminated iodine-avid lung metastases (DILM) of differentiated thyroid cancer (DTC). Using "post-therapy" 131-iodine ((131)I) whole-body scintigraphy (TxWBS) and thoracic computed tomography (CT), we retrospectively divi...

The usefulness of combined 2-[18F] fluoro-2-deoxy-D: -glucose positron emission tomography and computed tomography (FDG-PET/CT) in locating suspected recurrence in patients with iodine-negative differentiated thyroid cancer (DTC) was evaluated. Thirty-six patients with DTC and suspected iodine-negative recurrence underwent restaging with FDG-PET/CT...

To estimate the individual absorbed dose to the parotid and submandibular salivary glands in radioiodine therapy and its dependence from the previous cumulative therapy. Fifty-five patients with differentiated thyroid carcinoma after thyroidectomy received 1-21 GBq (131)I using single activities of 1-6 GBq. The patients were stratified according to...

Lymph node staging according to the TNM criteria is an essential part of tumor evaluation. Several morphological and functional imaging procedures are used complementarily in this setting. Dual-modality PET/CT scanners are able to provide anatomical and functional data sets in a single session with accurate image co-registration. Comparative studie...

Co-registration accuracy in combined whole-body (WB) PET/CT imaging is impaired by respiration-induced mismatches between the CT and the PET. Furthermore, PET/CT misregistration may bias the PET tracer distribution following CT-based attenuation correction (CT-AC). With the introduction of multi-row CT technology of up to 16 detector rows into PET/...

Maximum-likelihood (ML) estimation is an established paradigm for the assessment of imaging system performance in nonlinear quantitation tasks. At high signal-to-noise ratio (SNR), ML estimates are asymptotically Gaussian-distributed, unbiased and efficient, thereby attaining the Cramer-Rao bound (CRB). Therefore, at high SNR the CRB is useful as a...

We investigated radiation exposure of patients undergoing whole-body 18F-FDG PET/CT examinations at 4 hospitals equipped with different tomographs. Patient doses were estimated by using established dose coefficients for 18F-FDG and from thermoluminescent measurements performed on an anthropomorphic whole-body phantom. The most relevant difference b...

To assess the accuracy of positron emission tomography/computed tomography (PET/CT) when staging different malignant diseases. This was a retrospective, blinded, investigator-initiated study of 260 patients with various oncological diseases who underwent fluorine-18-2-fluoro-2-deoxy-d-glucose PET/CT for tumor staging. CT images alone, PET images al...

There has been a longstanding interest in fused images of anatomical information, such as that provided by computed tomography (CT) or magnetic resonance imaging (MRI) systems, with biological information obtainable by positron emission tomography (PET). The near-simultaneous data acquisition in a fixed combination of a PET and a CT scanner in a co...

To assess, in a pig model, the value of dual-modality positron emission tomography (PET)/computed tomography (CT) for monitoring radiation therapy. Central bile duct resection followed by creation of a biliodigestive anastomosis was performed in nine pigs. Six of these pigs were also treated with intraoperative radiation therapy (IORT) (20 Gy) in t...

Unlabelled: Since its introduction in 1998, dual-modality PET/CT imaging has received great attention in the medical community. For the first time, patients can be examined with both CT and PET in a single examination. A whole-body survey is the standard mode of acquisition. The CT images are used for anatomic reference of the tracer uptake patter...

For the past decade both, Computed Tomography (CT) and Positron Emission Tomography (PET) have been used widely, albeit frequently independently, in the management of cancer patients. To complement molecular and anatomical information such as obtained by PET and CT, respectively and thus facilitate a more accurate diagnosis1 both, retrospective sof...

To evaluate the effect of iodine- and barium-based contrast agents on the computed tomography (CT)-based positron emission tomography (PET) attenuation correction in dual-modality PET/CT. Experiments were conducted on a Society of Nuclear Medicine/National Electrical Manufacturers Association-PET phantom equipped with cylinders containing [18F]-2-f...

Blink reflex-related areas in the human cerebellum were studied using [15O]H2O PET in eight healthy subjects. Eyeblinks were evoked by airpuff stimulation and recorded via surface electrodes. PET analysis revealed a cerebellar increase of regional cerebral blood flow in vermal lobule VI and a small ipsilateral paravermal extension in the eyeblink c...

Numerous studies have shown that the cerebellum is involved in classical conditioning of specific aversive reactions. Only few studies, however, have examined the exact localization of cerebellar areas involved in the control of unconditioned reflex responses. The present study investigated cerebellar areas, which are activated during eliciting of...

Our objective was to show that oral and IV contrast materials improve CT image quality in dual-modality positron emission tomography (PET) and CT, resulting in an increase in diagnostic capacity. We also present a standardized scanning protocol for whole-body PET-CT with oral and IV contrast materials. To evaluate the use of whole-body PET-CT in cl...

Fear-conditioned potentiation of the startle response was used to study the role of the cerebellum in associative learning of non-specific aversive reactions in healthy human subjects using PET. Prior PET scanning initially neutral light stimuli were paired with painful electric shocks (fear-conditioning phase). Four PET-scans each were performed w...

We investigated the effects of resolution recovery and SPECT system sensitivity on performance in estimating binding potential (BP) from dynamic brain SPECT data obtained using I-123-altropane, a dopamine transporter imaging agent. BP is estimated by Fischman's approach, whereby a gamma variate function is fitted to the difference between striatal...

Three algorithms for scatter compensation in Tc-99m brain single-photon emission computed tomography (SPECT) were optimized and compared on the basis of the accuracy and precision with which lesion and background activity could be simultaneously estimated. These performance metrics are directly related to the clinically important tasks of activity...

We investigated the cortical activation pattern in a 30-year-old woman 4 years after multiple subpial transection (MST) of the right fronto-parietal cortex and six healthy controls using positron emission tomography. Sequential finger-to-thumb opposition at the frequency of 1.5 Hertz contralateral to the operated hemisphere was used as the activati...

The role of the human cerebellum in classical conditioning of the jaw-opening reflex was investigated using positron emission tomography (PET) in healthy subjects. The jaw-opening reflex was elicited by electrical stimulation of the right corner of the mouth (unconditioned stimulus, US). The conditioned stimulus was a tone preceding the US and cote...

The early detection of metastases from medullary thyroid cancer (MTC) is important because the only curative therapy consists in surgical removal of all tumour tissue. There is no single sensitive diagnostic imaging modality for the localization of all metastases in patients with MTC. Therefore, in many cases several imaging modalities (e.g. ultras...

We used serial positron emission tomography (PET) to study the evolution of functional brain activity within 12 weeks after a first subcortical stroke. Six hemiplegic stroke patients and three normal subjects were scanned twice (PET 1 and PET 2) by using passive elbow movements as an activation paradigm. Increases of regional cerebral blood flow co...

Cortical reorganization of motor systems has been found in recovered stroke patients. Reorganization in nonrecovered hemiplegic stroke patients early after stroke, however, is less well described. We used positron emission tomography to study the functional reorganization of motor and sensory systems in hemiplegic stroke patients before motor recov...

The performance of maximum-likelihood (ML) and maximum a posteriori (MAP) estimates in non-linear problems at low data SNR is not well predicted by the Cramér-Rao or other lower bounds on variance. In order to better characterize the distribution of ML and MAP estimates under these conditions, we derive a point approximation to density values of th...

The performance of Maximum Likelihood (ML) and Maximum a posteriori (MAP) estimates in nonlinear problems at low data SNR is not well predicted by the Cramér-Rao or other lower bounds on variance. In order to better characterize the distribution of ML and MAP estimates under these conditions, we derive an approximate density for the conditional dis...

Maximum-likelihood (ML) estimation is an established paradigm for the assessment of imaging system performance in nonlinear quantitation tasks. At high signal-to-noise ratio (SNR), maximum likelihood estimates are asymptotically normally distributed, unbiased, and efficient, thereby attaining the Cramer-Rao bound (CRB). Therefore, at high SNR the C...

Attenuation of photons degrades both the accuracy and the precision of SPECT images; attenuation correction algorithms correct the bias but cannot improve precision. Increased noise due to photon attenuation is most pronounced in regions deep in solid body sections, such as the brain and abdomen. We have quantified the degradation in performance in...

Changes of cerebellar blood flow were studied in normal humans using positron emission tomography (PET). A motor driven peg marked pairs of lines on subjects' right hands at different velocities. Subjects had to decide whether the second line was marked slower or faster than the first. Estimation of velocity (compared with control, i.e. presentatio...