Moshe Bocher

Gamma camera-mounted anatomical X-ray tomography: technology, system characteristics and first images

Abstract.Scintigraphic diagnosis, based on functional image interpretation, becomes more accurate and meaningful when supported by corresponding anatomical data. In order to produce anatomical images that are inherently registered with images of emission computerised tomography acquired with a gamma camera, an X-ray transmission system was mounted on the slip-ring gantry of a GEMS Millennium VG gamma camera. The X-ray imaging system is composed of an X-ray tube and a set of detectors located on opposite sides of the gantry rotor that moves around the patient along with the nuclear detectors. A cross-sectional anatomical transmission map is acquired as the system rotates around the patient in a manner similar to a third-generation computerised tomography (CT) system. Following transmission, single-photon emission tomography (SPET) or positron emission tomography (PET) coincidence detection images are acquired and the resultant emission images are thus inherently registered to the anatomical maps. Attenuation correction of the emission images is performed with the same anatomical maps to generate transmission maps. Phantom experiments of system performance and examples of first SPET and coincidence detection patient images are presented. Despite limitations of the system when compared with a state of the art CT scanner, the transmission anatomical maps allow for precise anatomical localisation and for attenuation correction of the emission images.

SPECT/CT hybrid imaging with 111In-pentetreotide in assessment of neuroendocrine tumours.

objective  Somatostatin receptor scintigraphy (SRS) of neuroendocrine (NE) tumours is often challenging because of minute lesion size and poor anatomic delineation. This study evaluates the impact of sequentially performed single‐photon emission computed tomography (SPECT)/CT fusion on SRS study interpretation and clinical management of these tumours.

Diagnostic dilemmas in parathyroid scintigraphy

Purpose Tc-99m MIBI scintigraphy can be useful for preoperative localization of parathyroid adenomas, despite its limited sensitivity. To refine interpretation, the authors conducted prospective reviews of the scintigraphic studies of patients with concomitant thyroid nodular disease and revised the false-negative and false-positive results. Materials and Methods Seventy-seven patients with primary hyperparathyroidism, associated with a solitary parathyroid adenoma, underwent dual-phase MIBI scintigraphy with subsequent injection of Tc-99m pertechnetate before surgery. The false-negative and false-positive scintigraphic findings were identified and revised. Results After surgery, revision of 19 false-negative scans of the total 77 studies led to the demonstration of an adenoma in seven patients. In five of the seven studies, the adenoma had been overlooked as a result of rapid tracer washout. Two additional small focal lesions would have also been identified if subtraction had been used for differences in contour of the MIBI and pertechnetate images. Four studies were interpreted falsely as abnormal, leading to a positive predictive value of 91%; three were associated with thyroid nodular disease. Conclusions Differential washout of MIBI from thyroid and parathyroid tissue is not universal. When MIBI is washed out rapidly from parathyroid adenomas, subtraction of a thyroid image should be performed and differences in contour delineated to localize the adenoma accurately. Some, but not all, thyroid lesions account for the false-positive findings.

Brain SPECT study of common ground between hypothyroidism and depression.

Hypothyroidism and major depressive disorder (MDD) share neuropsychiatric features. Cerebral perfusion deficits are found in both disorders. We compared regional cerebral blood flow (rCBF) in hypothyroidism and MDD to determine if clinical similarities are mediated by common neurocircuitry. Ten hypothyroid and 10 depressed patients underwent 99mTc-HMPAO-SPECT and clinical evaluation before and after response to respective treatments. Ten healthy controls underwent a similar, single, evaluation. Before treatment, rCBF in hypothyroid and depressed patients was lower than in controls, in posterior and anterior aspects of the brain respectively. rCBF in hypothyroidism was lower than in MDD in right posterior cingulate and parieto/occipital regions, and higher in frontal, prefrontal and sub-genual regions. Reduced rCBF in pre- and post-central gyri was found in both groups. Following treatment, rCBF in depressed patients increased and normalized, but remained unchanged in hypothyroidism. Affective symptoms in hypothyroidism may be mediated by neurocircuitry different from that of major depression.

Localization of parathyroid adenoma by ¹¹C-choline PET/CT: preliminary results.

Purpose This prospective pilot study was aimed to evaluate 11C-choline PET/CT (choline) as a tool for localization of parathyroid adenoma (PTA). Methods Forty patients with biochemical hyperparathyroidism underwent choline and 99mTc-MIBI imaging within a median interval of 56 days. Choline and MIBI images were analyzed and correlated with each other, with additional modalities such as ultrasound, CT, MRI, and with surgical findings, when available. Results Thirty-seven of forty cases were choline-positive, and 3 were choline-negative. Choline uptake on PET was identified with corresponding nodules on CT of the PET/CT, yielding precise localization. Twenty of thirty-seven foci were located in typical sites in the neck, and 17 were ectopic. Clear visualization of PTA was achieved in 33 of 37, whereas findings in 4 cases were suspicious for PTA. MIBI was positive in 33 of 40 cases (22 clearly positive, 11 suspicious). In 29 of 40 cases, choline and MIBI were concordant, but choline findings were clearer in 9 of these 29 studies. At the time of writing, 27 patients had undergone surgery. In 24 cases, there was complete matching of choline with surgical findings of PTA. Overall in 23 cases, both choline and MIBI matched surgical findings of PTA. In 1 case, PTA was correctly localized on choline but not on MIBI, and in 2 cases, neither choline nor MIBI corresponded to the surgical findings. Conclusions These preliminary results indicate that the combined functional and anatomical modality of choline PET/CT is a promising tool for PTA localization, providing clearer images than MIBI, equal or better accuracy, and quicker and easier acquisition.

Ga-68 DOTA-NOC uptake in the pancreas: pathological and physiological patterns.

Objective: Gallium-68 (Ga-68) DOTA-1-NaI3-octreotide (DOTA-NOC) positron emission tomography (PET)/computed tomography (CT) is increasingly used for neuroendocrine tumors (NETs), often found primarily in the pancreas. However, physiologic uptake of DOTA-NOC has been described in the uncinate process of the pancreas. We studied DOTA-NOC uptake in this organ. Materials and Methods: Ninety-six patients underwent 103 DOTA-NOC scans, with pathology-proven pancreatic NET (n = 40) and nonpancreatic NET or biochemical suspicion of NET (n = 63). Results: DOTA-NOC uptake was detected in 35 documented pancreatic tumor sites (SUV: 5.5–165; mean: 25.7 ± 28.8; median: 17.8). Among 63 cases without previous known pathology, uptake was suspicious for tumor in 24 sites (SUV: 4.7–35; mean 16.3 ± 8.0; median: 14.1), and in 38 sites, it was judged as physiological, generally lower relative to adjacent structures (SUV: 2.2–12.6; mean: 6.6 ± 2.2; median: 6.2). In 24 scans with suspected tumor and in 37 of 38 scans with physiological uptake, diagnostic computed tomography or magnetic resonance imaging or endoscopic ultrasonography failed to detect tumor. Conclusions: Pancreatic DOTA-NOC uptake must be interpreted with caution, and further studies are required.

Cerebral blood flow in depressed patients: a methodological comparison of statistical parametric mapping and region of interest analyses.

Functional brain imaging has assumed a leading role in neuropsychiatric research. However, findings reported for mental disorders often vary. Whether this reflects diversity in pathophysiology or heterogeneity of imaging techniques and data-analytic procedures is still unknown. This study compares region of interest (ROI) and statistical parametric mapping (SPM) analyses of a Tc99m-HMPAO single photon emission computed tomography (SPECT) imaging study of 23 depressed and 21 control subjects. Reduced regional cerebral blood flow (rCBF) was demonstrated by both methods in the right parietal and occipital lobes, but additional regions were identified only on ROI analysis (left temporal) and only on SPM analysis (left parietal). To investigate the contribution of SPM spatial normalization to these discrepancies, further ROI analyses were performed, applying the original ROI templates to normalized images, and applying regions identified by SPM to the original images. This study demonstrated considerable overlap in findings of SPM and ROI analyses. Differences between these methods may be mostly related to subjective placement of ROIs in ROI analysis, and standardized warping inherent in normalization in SPM. Given the advantages and drawbacks of each procedure, the choice of methodology should be determined in accordance with the study design, and complementary use of both methods may be considered.

Imaging Coronary Sinus Infection in Pacemaker Electrode with [18F]-Fluorodeoxyglucose Positron Emission Tomography

Imaging Coronary Sinus Infection in Pacemaker Electrode with [18F]-Fluorodeoxyglucose Positron Emission Tomography MOGHER KHAMAISI, M.D., PH.D.,∗ AHARON MEDINA, M.D.,† BENJAMIN MAZOUZ, M.D.,† and MOSHE BOCHER, M.D.‡ From the ∗Department of Medicine, and ‡Department of Medical Biophysics and Nuclear Medicine, Hebrew University, Hadassah Medical School, Jerusalem, Israel; and †Division of Cardiology, Bikur Cholim Hospital, Jerusalem, Israel

Structure–Activity Relationship and Preclinical Evaluation of Carbon-11-Labeled Ammonium Salts as PET–Myocardial Perfusion Imaging Agents

BackgroundDue to the limited availability of suitable positron emission tomography (PET) tracers, the majority of myocardial perfusion imaging (MPI) scans is performed using SPECT rather than PET.AimThe aim of this study is to design and synthesize carbon-11-labeled ammonium salt derivatives and explore their structure–activity relationship (SAR) and their potential as PET–MPI agents.Methods and ResultsThree carbon-11-labeled ammonium salts were developed. SAR of the labeled compounds were explored vis-à-vis the effects of charge density and lipophilicity on the distribution kinetics in mice. These studies pointed at [11C]4 as the lead compound. Comparative microPET/CT scans in healthy rats, using both [11C]4 and [13 N]–NH3, substantiated the potential of [11C]4 ([11C]-DMDPA). A proof of concept for the potential of radiolabeled ammonium salts as MPI agents has been demonstrated in a newly developed swine model of permanent partial coronary artery occlusion.ConclusionsSAR studies of 11C-labeled ammonium salts suggest that both lipophilicity and charge density affect the performance of these compounds as MPI probes. In a swine model, the labeled lead successfully visualized the defect regions in the myocardium. The data presented call for the development of fluorine-18 analogues, to increase clinical impact.

Estimating Relative Renal Function from Relative Parenchymal Volume—A Feasibility Study

BACKGROUND Relative kidney function is an important parameter during urological decision making. OBJECTIVE In this study, we evaluated the feasibility of estimating relative kidney function from relative kidney parenchymal volume determined by non-enhanced CT. DESIGN SETTING AND PARTICIPANTS Between the years 2005 to 2007 twenty-seven patients underwent both non-enhanced CT and renal scintigraphy within three months in our hospital. The indications for CT scanning were: evaluation of stone disease in 18 patients (66%), workup before or after a urological procedure in 7 (26%), suspected ureteral obstruction and prostate cancer with urosepsis each in a single patient. INTERVENTION A region of interest (ROI) was manually drawn around the edges of each kidney, excluding the collecting system, renal cysts and tumors. Kidney volumes were extrapolated by summation of all measured ROIs on a dedicated workstation. Relative kidney volume was calculated as the ratio between individual and total kidney volumes. MEASUREMENTS Relative kidney volume as measured by CT was compared to relative kidney function as measured by scintigraphy. RESULTS AND LIMITATIONS Relative kidney volume correlated well with relative kidney function (Pearson correlation coefficient r = 0.92), and this good correlation prevailed over a wide range of relative kidney functions (from 15% to 87%). Mean individual difference between the CT and scintigraphy ratios was 5.7% (S.D. 4.6%). In 89% of the patients the difference was less then 10%, and in none more than 18%. Kidney morphological configurations on non-enhanced CT closely resembled the functional configuration on scintigraphy. This preliminary study is limited by the small number of cases and cases of acute deterioration in kidney function were not included. CONCLUSIONS In this preliminary study we showed that relative kidney parenchymal volume measured by nonenhanced CT images may provide a close estimate of kidney relative function.