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Background: Quantitative thresholds are helpful to define an abnormal DaT SPECT in patients with suspected nigrostriatal degenerative diseases (NSDD). The optimal DaTQUANT threshold for diagnostic accuracy of DaT SPECT across combined movement and cognitive disorder populations has been previously described. Methods : We established optimal DaTQUANT thresholds that enhance the discrimination between dementia with Lewy bodies (DLB) and non-DLB dementia types, as well as between Parkinsonian syndromes (PS) and conditions not characterized by nigrostriatal degeneration (non-PS). Results: Data from a total of 303 patients were used in this retrospective analysis. Posterior putamen of the more affected hemisphere (MAH) was shown to be an accurate single-variable predictor for both DLB and PS and was comparable to the most accurate multi-variable models. Conclusions: Automated quantification with DaTQUANT can accurately aid in the differentiation of DLB from non-DLB dementias and PS from non-PS. Optimal thresholds for assisting a diagnosis of DLB are striatal binding ratio (SBR) ≤ 0.65, z-score ≤ -2.36, and a percent deviation ≤ -0.54 for the posterior putamen of the MAH. Optimal posterior putamen thresholds for assisting a diagnosis of PS are SBR ≤ 0.92, z-score ≤ -1.53, and a percent deviation ≤ -0.33, which are similar to our previously reported posterior putamen threshold values using a blended patient pool from multiple study populations.

Objective. Single-photon emission computed tomography (SPECT) with pinhole collimators can provide high-resolution imaging, but is often limited by low sensitivity. Acquiring projections simultaneously through multiple pinholes affords both high resolution and high sensitivity. However, the overlap of projections from different pinholes on detectors, known as multiplexing, has been shown to cause artefacts which degrade reconstructed images. Approach. Multiplexed projection sets were considered here using an analytic simulation model of AdaptiSPECT-C-a brain-dedicated multi-pinhole SPECT system. AdaptiSPECT-C has fully adaptable aperture shutters, so can acquire projections with a combination of multiplexed and non-multiplexed frames using temporal shuttering. Two strategies for reducing multiplex artefacts were considered: an algorithm to de-multiplex projections, and an alternating reconstruction strategy for projections acquired with a combination of multiplexed and non-multiplexed frames. Geometric and anthropomorphic digital phantoms were used to assess a number of metrics. Main results. Both de-multiplexing strategies showed a significant reduction in image artefacts and improved fidelity, image uniformity, contrast recovery and activity recovery (AR). In all cases, the two de-multiplexing strategies resulted in superior metrics to those from images acquired with only mux-free frames. The de-multiplexing algorithm provided reduced image noise and superior uniformity, whereas the alternating strategy improved contrast and AR. Significance. The use of these de-multiplexing algorithms means that multi-pinhole SPECT systems can acquire projections with more multiplexing without degradation of images., (© 2024 Institute of Physics and Engineering in Medicine.)

Objective. Monte-Carlo simulation studies have been essential for advancing various developments in single photon emission computed tomography (SPECT) imaging, such as system design and accurate image reconstruction. Among the simulation software available, Geant4 application for tomographic emission (GATE) is one of the most used simulation toolkits in nuclear medicine, which allows building systems and attenuation phantom geometries based on the combination of idealized volumes. However, these idealized volumes are inadequate for modeling free-form shape components of such geometries. Recent GATE versions alleviate these major limitations by allowing users to import triangulated surface meshes. Approach. In this study, we describe our mesh-based simulations of a next-generation multi-pinhole SPECT system dedicated to clinical brain imaging, called AdaptiSPECT-C. To simulate realistic imaging data, we incorporated in our simulation the XCAT phantom, which provides an advanced anatomical description of the human body. An additional challenge with the AdaptiSPECT-C geometry is that the default voxelized XCAT attenuation phantom was not usable in our simulation due to intersection of objects of dissimilar materials caused by overlap of the air containing regions of the XCAT beyond the surface of the phantom and the components of the imaging system. Main results. We validated our mesh-based modeling against the one constructed by idealized volumes for a simplified single vertex configuration of AdaptiSPECT-C through simulated projection data of 123 I-activity distributions. We resolved the overlap conflict by creating and incorporating a mesh-based attenuation phantom following a volume hierarchy. We then evaluated our reconstructions with attenuation and scatter correction for projections obtained from simulation consisting of mesh-based modeling of the system and the attenuation phantom for brain imaging. Our approach demonstrated similar performance as the reference scheme simulated in air for uniform and clinical-like 123 I-IMP brain perfusion source distributions. Significance. This work enables the simulation of complex SPECT acquisitions and reconstructions for emulating realistic imaging data close to those of actual patients., (© 2023 Institute of Physics and Engineering in Medicine.)

Application of multi-pinhole collimator in pinhole-based SPECT increases detection sensitivity. The presence of multiplexing in projection images due to the usage of multiple pinholes can further improve the sensitivity at the cost of adding data ambiguity. We are developing a next-generation adaptive brain-dedicated SPECT system -AdaptiSPECT-C. The AdaptiSPECT-C can adapt the multiplexing level and system sensitivity using adaptable pinhole modules. In this study, we investigated the performance of 4 data acquisition schemes with different multiplexing levels and sensitivities on cerebral SPECT imaging. Schemes #1, #2, and #3 have <1%, 67%, and 31% overall multiplexing, respectively, while the 4th scheme without multiplexing is considered as ground truth. The ground-truth and schemes #1-3 have 1.0, 1.7, 5.1, and 4.0 times higher sensitivity, respectively, compared to a dual-headed parallel-hole SPECT system at matched spatial resolution. A customized XCAT brain perfusion digital phantom emulating the distribution of I-123 N-isopropyl iodoamphetamine (IMP) in a 99th percentile size male was used for simulations. Data acquisition for each scheme was performed at two count levels (low-count and high-count relative to the recommended clinical count level). The normalized root-mean-square error (NRMSE) for schemes #1, #2, and #3 with the low-count (high-count) scenario showed 11%, 4%, and 5% (10%, 5%, and 6%) deviation, respectively, from that of the multiplex-free ground truth. For both the low-count and high-count scenarios, scheme #1 resulted in the least accurate activity ratio (AR) for almost all the analyzed gray-matter brain regions. Further schemes #2 or #3 led to the most accurate AR values with both low-count and high-count scenarios for all the analyzed gray-matter regions. It was thus observed that even with this large head size which leads to significant multiplexing levels, the higher sensitivity from multiplexing could to some extent mitigate the data ambiguity and be translated into reconstructed images of higher quality., (© 2021 IOP Publishing Ltd.)

We are developing a multi-detector pinhole-based stationary brain-dedicated SPECT system: AdaptiSPECT-C. In this work, we introduced a new design prototype with multiple adaptable pinhole apertures for each detector to modulate the multiplexing by employing temporal shuttering of apertures. Temporal shuttering of apertures over the scan time provides the AdaptiSPECT-C with the capability of multiple-frame acquisition. We investigated, through analytic simulation, the impact of projection multiplexing on image quality using several digital phantoms and a customized anthropomorphic phantom emulating brain perfusion clinical distribution. The 105 pinholes in the collimator of the system were categorized into central, axial, and lateral apertures. We generated, through simulation, collimators of different multiplexing levels. Several data acquisition schemes were also created by changing the imaging time share of the acquisition frames. Sensitivity increased by 35% compared to the single-pinhole-per-detector base configuration of the AdaptiSPECT-C when using the central, axial, and lateral apertures with equal acquisition time shares within a triple-frame scheme with a high multiplexing scenario. Axial and angular sampling of the base configuration was enhanced by adding the axial and lateral apertures. We showed that the temporal shuttering of apertures can be exploited, trading the sensitivity, to modulate the multiplexing and to acquire a set of non-multiplexed non-truncated projections. Our results suggested that reconstruction benefited from utilizing both non-multiplexed projections and projections with modulated multiplexing resulting in a noticeably reduction in the multiplexing-induced image artefacts. Contrast recovery factor improved by 20% (9%) compared to the base configuration for a Defrise (hot-rod) phantom study when the central and axial (lateral) apertures with equal time shares were combined. The results revealed that, as an overall trend at each simulated multiplexing level, lowest normalized root-mean-square errors for the brain gray-matter regions were achieved with the combined usage of the central apertures and axial/lateral apertures.

With brain-dedicated multi-detector systems employing pinhole apertures the usage of detectors facing the top of the patient's head (i.e. quasi-vertex (QV) views) can provide the advantage of additional viewing from close to the brain for improved detector coverage. In this paper, we report the results of simulation and reconstruction studies to investigate the impact of the QV views on the imaging performance of AdaptiSPECT-C, a brain-dedicated stationary SPECT system under development. In this design, both primary and scatter photons from regions located inferior to the brain can contribute to SPECT projections acquired by the QV views, and thus degrade AdaptiSPECT-C imaging performance. In this work, we determined the proportion, origin, and nature (i.e. primary, scatter, and multiple-scatter) of counts emitted from structures within the head and throughout the body contributing to projections from the different AdaptiSPECT-C detector rings, as well as from a true vertex view detector. We simulated phantoms used to assess different aspects of image quality (i.e. uniform activity concentration sphere, and Derenzo), as well as anthropomorphic phantoms with different count levels emulating clinical 123 I activity distributions (i.e. DaTscan and perfusion). We determined that attenuation and scatter in the patient's body greatly diminish the probability of the photons emitted outside the volume of interest reaching to detectors and being recorded within the 15% photopeak energy window. In addition, we demonstrated that the inclusion of the residual of such counts in the system acquisition does not degrade visual interpretation or quantitative analysis. The addition of the QV detectors improves volumetric sensitivity, angular sampling, and spatial resolution leading to significant enhancement in image quality, especially in the striato-thalamic and superior regions of the brain. Besides, the use of QV detectors improves the recovery of clinically relevant metrics such as the striatal binding ratio and mean activity in selected cerebral structures. Our findings proving the usefulness of the QV ring for brain imaging with 123 I agents can be generalized to other commonly used SPECT imaging agents labelled with isotopes, such as 99m Tc and likely 111 In.

We designed a dedicated multi-detector multi-pinhole brain SPECT scanner to generate images of higher quality compared to general-purpose systems. The system, AdaptiSPECT-C, is intended to adapt its sensitivity-resolution trade-off by varying its aperture configurations allowing both high-sensitivity dynamic and high-spatial-resolution static imaging. The current system design consists of 23 detector heads arranged in a truncated spherical geometry. In this work, we investigated the axial and angular sampling capability of the current stationary system design. Two data acquisition schemes using limited rotation of the gantry and two others using axial translation of the imaging bed were also evaluated concerning their impact on image quality through improved sampling. Increasing both angular and axial sampling in the current prototype system resulted in quantitative improvements in image quality metrics and qualitative appearance of the images as determined in studies with specifically selected phantoms. Visual improvements for the brain phantoms with clinical distributions were less pronounced but presented quantitative improvements in the fidelity (normalized root-mean-square error (NRMSE)) and striatal specific binding ratio (SBR) for a dopamine transporter (DAT) distribution, and in NRMSE and activity recovery for a brain perfusion distribution. More pronounced improvements with increased sampling were seen in contrast recovery coefficient, bias, and coefficient of variation for a lesion in the brain perfusion distribution. The negligible impact of the most cranial ring of detectors on axial sampling, but its significant impact on sensitivity and angular sampling in the cranial portion of the imaging volume-of-interest were also determined.

Dopamine transporter SPECT with I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane (I-ioflupane) aids in the diagnosis of parkinsonian syndrome by demonstrating loss of striatal dopamine transporters, proportional to nigrostriatal dopaminergic neuronal loss. Quantitative software analysis (QSA) is a helpful adjunct to visual interpretation. An atlas of pearls and pitfalls of QSA is presented. Examples include correction for head tilt/orientation, scaling artifacts, and detection of balanced loss of activity. Additional examples are provided where QSA can potentially fail such as patient variation and vascular disease.

OBJECTIVE. The purpose of this article is to provide a review of 123 I-ioflupane SPECT in the evaluation of suspected parkinsonian syndromes (PSs). This collection of diseases presents frequent diagnostic challenges, even by movement disorder and dementia specialists. CONCLUSION. The 123 I-ioflupane scan serves as an imaging biomarker of the status of presynaptic dopamine transporters (DATs) in the striatum. As a result of neuronal death, DATs are greatly reduced in patients with PS neurodegenerative disorders, whereas clinical mimics generally do not show striatal DAT loss. This provides a tremendous opportunity for 123 I-ioflupane to aid in the accurate and timely diagnosis of these patients and optimize their management.

Quantitative assessment of dopamine transporter imaging can aid in diagnosing Parkinson disease (PD) and assessing disease progression in the context of therapeutic trials. Previously, the software program SBRquant was applied to 123 I-ioflupane SPECT images acquired on healthy controls and subjects with PD. Earlier work on optimization of the parameters for differentiating between controls and subjects with dopaminergic deficits is extended here for maximizing change measurements associated with disease progression on longitudinally acquired scans. Methods: Serial 123 I-ioflupane SPECT imaging for 51 subjects with PD (conducted approximately 1 y apart) were downloaded from the Parkinson Progression Markers Initiative database. The software program SBRquant calculates the striatal binding ratio (SBR) separately for the left and right caudates and putamen regions of interest (ROIs). Parameters were varied to evaluate the number of summed transverse slices and the positioning of the striatal ROIs for determining the signal-to-noise ratio associated with their annual rate of change in SBR. The parameters yielding the largest change in the lowest putamen's SBR from scan 1 to scan 2 were determined. Results: From scan 1 to scan 2 in the 51 subjects, the largest annual change was observed when the putamen ROI was placed 3 pixels away from the caudate and by summing 5 central striatal slices. This resulted in an 11.2% ± 4.3% annual decrease in the lowest putamen SBR for the group. Conclusion: Quantitative assessment of dopamine transporter imaging for assessing progression of PD requires specific, optimal parameters different from those for diagnostic accuracy., (© 2019 by the Society of Nuclear Medicine and Molecular Imaging.)

Dopamine transporter SPECT is an accurate adjunct to clinical evaluation for Parkinson disease when the diagnosis is difficult. Dopaminergic medications may significantly affect dopamine transporter availability and, thus, uptake of dopamine transporter tracers. A patient had a false-positive dopamine transporter SPECT result while she was taking dextroamphetamine and amphetamine for attention-deficit hyperactivity disorder. The SPECT findings normalized after amphetamine therapy was withheld. An accurate medication history combined with knowledge of drugs that interfere with dopamine transporter imaging is critical to ensure accuracy., (© 2018 by the Society of Nuclear Medicine and Molecular Imaging.)

Purpose: Dopamine transporter (DaT) imaging is an adjunct diagnostic tool in parkinsonian disorders. Interpretation of DaT scans is based on visual reads. SBRquant is an automated method that measures the striatal binding ratio (SBR) in DaT scans, but has yet to be optimized. We aimed to (1) optimize SBRquant parameters to distinguish between patients with Parkinson disease (PD) and healthy controls using the Parkinson's Progression Markers Initiative (PPMI) database and (2) test the validity of these parameters in an outpatient cohort., Methods: For optimization, 336 DaT scans (215 PD patients and 121 healthy controls) from the PPMI database were used. Striatal binding ratio was calculated varying the number of summed transverse slices (N) and positions of the striatal regions of interest (d). The resulting SBRs were evaluated using area under the receiver operating characteristic curve. The optimized parameters were then applied to 77 test patients (35 PD and 42 non-PD patients). Striatal binding ratios were also correlated with clinical measures in the PPMI-PD group., Results: The optimal parameters discriminated the training groups in the PPMI cohort with 95.8% sensitivity and 98.3% specificity (lowest putamen SBR threshold, 1.037). The same parameters discriminated the groups in the test cohort with 97.1% sensitivity and 100% specificity (lowest putamen SBR threshold, 0.875). A significant negative correlation (r = -0.24, P = 0.0004) was found between putamen SBRs and motor severity in the PPMI-PD group., Conclusions: SBRquant discriminates DaT scans with high sensitivity and specificity. It has a high potential for use as a quantitative diagnostic aid in clinical and research settings.

Visual interpretation of 123 I-ioflupane SPECT images has high diagnostic accuracy for differentiating parkinsonian syndromes (PS), from essential tremor and probable dementia with Lewy bodies (DLB) from Alzheimer disease. In this study, we investigated the impact on accuracy and reader confidence offered by the addition of image quantification in comparison with visual interpretation alone. Methods: We collected 304 123 I-ioflupane images from 3 trials that included subjects with a clinical diagnosis of PS, non-PS (mainly essential tremor), probable DLB, and non-DLB (mainly Alzheimer disease). Images were reconstructed with standardized parameters before striatal binding ratios were quantified against a normal database. Images were assessed by 5 nuclear medicine physicians who had limited prior experience with 123 I-ioflupane interpretation. In 2 readings at least 1 mo apart, readers performed either a visual interpretation alone or a combined reading (i.e., visual plus quantitative data were available). Readers were asked to rate their confidence of image interpretation and judge scans as easy or difficult to read. Diagnostic accuracy was assessed by comparing image results with the standard of truth (i.e., diagnosis at follow-up) by measuring the positive percentage of agreement (equivalent to sensitivity) and the negative percentage of agreement (equivalent to specificity). The hypothesis that the results of the combined reading were not inferior to the results of the visual reading analysis was tested. Results: A comparison of the combined reading and the visual reading revealed a small, insignificant increase in the mean negative percentage of agreement (89.9% vs. 87.9%) and equivalent positive percentages of agreement (80.2% vs. 80.1%). Readers who initially performed a combined analysis had significantly greater accuracy (85.8% vs. 79.2%; P = 0.018), and their accuracy was close to that of the expert readers in the original studies (range, 83.3%-87.2%). Mean reader confidence in the interpretation of images showed a significant improvement when combined analysis was used ( P < 0.0001). Conclusion: The addition of quantification allowed readers with limited experience in the interpretation of 123 I-ioflupane SPECT scans to have diagnostic accuracy equivalent to that of the experienced readers in the initial studies. Also, the results of the combined reading were not inferior to the results of the visual reading analysis and offered an increase in reader confidence., (© 2017 by the Society of Nuclear Medicine and Molecular Imaging.)

Purpose: Dopamine transporter single-photon emission computed tomography imaging utilizing iodine-123 ioflupane is accurate for differentiation of Parkinson disease from essential tremor. This study evaluates how reimbursement for I-123 ioflupane imaging changed between 2011 (year of FDA approval) and 2014 (year after loss of pass-through status for hospital-based outpatient imaging from CMS)., Methods: I-123 ioflupane reimbursement data for our institution's hospital-based imaging were compared between two periods: (1) July 2011 to October 2012, and (2) 2014. For each time period separately and in combination, averages and ranges of reimbursement for private insurance and CMS were analyzed and compared. A model to ensure recouping of radiopharmaceutical costs was developed., Results: Review yielded 247 studies from July 2011 to October 2012 and 94 studies from 2014. Average reimbursement per study fell from $2,469 (US dollars) in 2011 to 2012 to $1,657 in 2014. CMS reduced average reimbursement by $1,148 in 2014 because of loss of radiopharmaceutical pass-through status. Average reimbursements from CMS versus private payors markedly differed in 2011 to 2012 at $2,266 versus $2,861, respectively, and in 2014 at $1,118 versus $3,470, respectively. Between 2011 to 2012 and 2014, the CMS percentage increased from 54% to 78%. Assuming that I-123 ioflupane cost $2,000, our model based on 2014 data predicts a practice with greater than 60% CMS patients would no longer recover radiopharmaceutical costs., Conclusions: Reimbursement levels, payor mix, scanner location, and radiopharmaceutical costs are all critical, variable factors for modeling the financial viability of I-123 ioflupane imaging and, by extrapolation, future radiopharmaceuticals., (Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Unlabelled: The goal of this study was to evaluate the diagnostic accuracy, cost-effectiveness, and appropriate use of SPECT myocardial perfusion imaging (SMPI) versus stress echocardiography in the preoperative evaluation of patients for kidney transplantation., Methods: A single-institution, retrospective study was performed. SMPI was performed with regadenoson and stress echocardiography predominantly with dobutamine. Findings on subsequent coronary angiography were correlated. A cost analysis for SMPI versus stress echocardiography was modeled using reimbursements from the Center for Medicare Services., Results: One hundred thirteen patients underwent imaging (53 SMPI and 60 stress echocardiography). One hundred percent of SMPI studies were diagnostic, compared with only 80% (48/60) in the stress echocardiography group, and this result was statistically significant (χ(2) = 7.96, P < 0.01). The most common reason for a nondiagnostic test was not reaching the target heart rate. In the SMPI group, 15% (8/53) of patients had ischemia on imaging and all underwent subsequent coronary angiography, which confirmed obstructive coronary lesions. One patient with a negative SMPI result underwent a subsequent angiogram that was negative. In the stress echocardiography group, 5% (3/60) of patients had ischemia on imaging and 2 underwent subsequent angiography, which was negative. Three of 12 patients with nondiagnostic examinations underwent further testing. One patient underwent a follow-up positive SMPI scan but no subsequent coronary angiography. The other 2 patients underwent coronary angiography, which was negative. Of the 45 negative stress echocardiography patients, 6 (13%) underwent angiography, with a positive result for obstructive coronary artery disease in 3 of 6. For the modeling of cost analysis, rates of $1,173 and $1,521 (Center for Medicare Services) were used for SMPI and stress echocardiography, respectively. The model assumed that all nondiagnostic imaging would be referred for further stress testing (i.e., nondiagnostic stress echocardiography would be referred for SMPI). This model estimated that initial noninvasive testing with stress echocardiography versus SMPI resulted in a 50% greater cost., Conclusion: For the preoperative evaluation of kidney transplantation, SMPI is more often diagnostic than stress echocardiography. A cost model estimates that initial noninvasive diagnostic testing with stress echocardiography would result in an approximately 50% greater cost than SMPI. Our data also suggest that SMPI has greater diagnostic accuracy than stress echocardiography. Therefore, this single-institution experience supports SMPI as the more appropriate test., (© 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

Patients were surveyed to assess the impact of dopamine transporter imaging on diagnostic confidence, change in treatment plan, effect on medication compliance, and subjective well-being. Surveys were sent to 140 patients who completed dopamine transporter imaging an average of 18 months prior. Sixty-five surveys from patients (46%) were returned. Questions assessed patients' perceived impact of the imaging on their care. Increased diagnostic confidence following imaging was reported by 69% of patients. Changes to treatment plan from imaging were reported by 24% of patients. Overall satisfaction with the study and its impact was reported by 70% of patients. Dopamine transporter imaging increased diagnostic confidence among patients and overall patient satisfaction with the impact of imaging on clinical care was high.

Unlabelled: An automated objective striatal analysis (OSA) software program was applied to dopamine transporter (123)I-ioflupane images acquired on subjects with varying severities of parkinsonism. The striatal binding ratios (SBR) of the left and right putamina (relative to the occipital lobe) were computed, and the laterality of that measure was compared with clinical symptoms and visual reads. The objective over-read of OSA was evaluated as an aid in confirming the laterality of disease onset., Methods: One hundred one (123)I-ioflupane scans were acquired on clinically referred subjects. SPECT images were analyzed using the OSA software, which locates the slices containing the striatal and background (occipital) structures, positions regions over the left and right caudate nuclei and putamina, and calculates the background-subtracted SBR. Seven images were uninterpretable because of patient motion or lack of visualization of the striatum. The remaining 94 scans were analyzed with OSA. Differences between left and right putaminal SBR ranged from 0% to 36.6%, with a mean of 11.4%. When the difference between the SBR of the left and right putamina was greater than 6%, the lower side was taken as the side of onset. Left-to-right differences less than 6% were considered to be nonlateralizing (symmetric). The 94 scans were reviewed independently by 3 masked expert readers. By majority consensus, abnormal findings were seen on 67 of the 94 scans, of which 46 had available clinical findings., Results: Clinically, 34 subjects presented with lateralized tremors and 12 with symmetric or no tremors. Of the 34 cases of clinically lateralized tremors, 26 (76%) were concordant with the OSA findings, 5 were disparate with OSA (15%), and in 3 the OSA results were symmetric (9%). For the same 34 patients, the visual reads were concurrent with clinical tremor findings in 24 cases (71%), 1 was disparate (3%), and 9 visual reads were symmetric (26%). Of the 9 scans deemed symmetric by readers, 4 were correctly lateralized by OSA, and of the 3 symmetric OSA results, 2 were correctly lateralized visually., Conclusion: The OSA program may be a helpful aid in the interpretation of (123)I-ioflupane SPECT images for determining laterality representing the asymmetric loss of dopamine transporters in the striata. OSA offers an objective, reproducible over-read evaluation for the laterality of onset in Parkinson disease., (© 2014 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

Parkinson's disease (PD), the second-most common neurodegenerative disease, is characterized by motor and nonmotor symptoms. PD is often misdiagnosed; inappropriate treatment due to misdiagnosis has undesired consequences, as does delayed diagnosis. Unfortunately, most people with PD receive a diagnosis only after motor symptoms have emerged, by which time 40% to 60% of dopamine neurons have already been lost. Advances in imaging techniques have provided clinicians with increasingly sophisticated tools. In 2011, the US Food and Drug Administration approved ioflupane I-123 injection (DaTscanTM) for striatal dopamine transporter visualization using single-photon emission computed tomography (SPECT) imaging, which provides an effective tool for assessing striatal dopaminergic deficiency. Among patients with suspected parkinsonian syndromes, of which PD is one, the diagnostic sensitivity and specificity of DaTscan SPECT imaging are high. In clinical studies that were part of the DaTscan new drug application, no serious drug-related adverse events reported by the 1236 participants were attributed to DaTscan. The introduction of DaTscan imaging and its utility necessitate the development of clinical recommendations for appropriate use; thus, a multidisciplinary panel of experts was convened to develop clinical criteria and algorithms to help guide clinicians and managed care organizations in the application of DaTscan SPECT imaging. Based on the consensus of this expert panel, appropriate use of DaTscan SPECT imaging includes cases where: (1) PD diagnosis is uncertain; (2) tremor of uncertain etiology is present; and (3) nonmotor and/ or supportive symptoms and features associated with PD are present but the classical motor syndrome is absent or atypical.

This case study illustrates the pattern and significance of the pinwheel sign, a SPECT artifact from rotational head motion that can complicate the diagnosis of Parkinson disease. Monitoring the patient during image acquisition is crucial since rotational motion artifacts are difficult to identify on raw or processed images and may lead to incorrect interpretation of findings.

Unlabelled: A fully automated objective striatal analysis (OSA) program that quantitates dopamine transporter uptake in subjects with suspected Parkinson's disease was applied to images from clinical (123)I-ioflupane studies. The striatal binding ratios or alternatively the specific binding ratio (SBR) of the lowest putamen uptake was computed, and receiver-operating-characteristic (ROC) analysis was applied to 94 subjects to determine the best discriminator using this quantitative method., Methods: Ninety-four (123)I-ioflupane SPECT scans were analyzed from patients referred to our clinical imaging department and were reconstructed using the manufacturer-supplied reconstruction and filtering parameters for the radiotracer. Three trained readers conducted independent visual interpretations and reported each case as either normal or showing dopaminergic deficit (abnormal). The same images were analyzed using the OSA software, which locates the striatal and occipital structures and places regions of interest on the caudate and putamen. Additionally, the OSA places a region of interest on the occipital region that is used to calculate the background-subtracted SBR. The lower SBR of the 2 putamen regions was taken as the quantitative report. The 33 normal (bilateral comma-shaped striata) and 61 abnormal (unilateral or bilateral dopaminergic deficit) studies were analyzed to generate ROC curves., Results: Twenty-nine of the scans were interpreted as normal and 59 as abnormal by all 3 readers. For 12 scans, the 3 readers did not unanimously agree in their interpretations (discordant). The ROC analysis, which used the visual-majority-consensus interpretation from the readers as the gold standard, yielded an area under the curve of 0.958 when using 1.08 as the threshold SBR for the lowest putamen. The sensitivity and specificity of the automated quantitative analysis were 95% and 89%, respectively., Conclusion: The OSA program delivers SBR quantitative values that have a high sensitivity and specificity, compared with visual interpretations by trained nuclear medicine readers. Such a program could be a helpful aid for readers not yet experienced with (123)I-ioflupane SPECT images and if further adapted and validated may be useful to assess disease progression during pharmaceutical testing of therapies.