Anterior Planar Images Research Articles

99mTc]Tc-hydroxydiphosphonate uptake in soft tissue is associated with amyloid load in subcutaneous abdominal fat tissue and mortality in wild-type transthyretin amyloidosis patients.

Bone scintigraphy is key to non-invasively diagnosing wild-type transthyretin (ATTRwt) amyloidosis, and is mainly used to assess cardiac radiotracer uptake. However, extracardiac radiotracer uptake is also observed. We investigated whether intensity of soft tissue radiotracer uptake is associated with amyloid load in subcutaneous abdominal fat tissue and with mortality. This prospective cohort study included 94 ATTRwt amyloidosis patients and 26 amyloid-negative heart failure controls who underwent whole-body [99mTc]Tc-hydroxydiphosphonate scintigraphy. Site-to-background ratios were calculated for heart, elbows, subcutaneous tissue, shoulders and wrists on anterior planar bone scintigraphy images using rib and whole-body radiotracer uptake as background. Fat tissue aspirates were stained with Congo red to grade amyloid load. Site-to-rib ratios were compared between ATTRwt amyloidosis patients and controls, and associations of site-to-background ratio with Congo red score and all-cause mortality were studied. ATTRwt amyloidosis patients had higher soft tissue-to-rib, heart-to-rib and heart-to-whole body ratios compared with controls. The intensity of soft tissue uptake was positively associated with amyloid load in fat tissue in ATTRwt amyloidosis patients. Estimated glomerular filtration rate, N-terminal brain natriuretic propeptide, high-sensitivity cardiac troponin T (hs-cTnT), and the prognostic Mayo and NAC staging system were associated with all-cause mortality in univariable models. Soft tissue/rib ratio, hs-cTnT and the prognostic staging systems were the only two variables that were independently associated withall-cause mortality. Soft tissue radiotracer uptake on bone scintigraphy in ATTRwt amyloidosis patients is positively associated with amyloid load in abdominal fat tissue and is independently associated with mortality.

<sup>99m</sup>Tc-1-Thio-D-Glucose in Lymphoma Patients: Safety, Pharmacokinetics and Dosimetric Characteristics

Purpose : To study the safety of 99m Tc-1-Thio-D-Glucose ( 99m Tc-TG) using, as well as its pharmacokinetics and dosimetric characteristics. Material and methods : The pharmacokinetics of 99mTc-TG was studied in 12 patients with lymphomas. The study was performed after a bolus injection of 729 ± 102 MBq 99m Tc-TG. Whole body anterior and posterior planar imaging was performed at 2, 4, 6, and 24 hours post-injection. In addition, all patients underwent SPECT/CT scanning at 2 hours and only SPECT at 4 and 6 hours after injection. To determine the dynamics of 99m Tc-TG accumulation in organs and tissues, the corresponding regions of interest (ROI) were outlined on each of the scans. Absorbed doses were calculated using a specialized OLINDA/EXM 1.1 program using phantoms of adult women and men. Results : The study showed that the administration of 99m Tc-TG is well tolerated by patients and is not accompanied by any side effects. The specified radiopharmaceutical has favorable dosimetric properties. Thus, in the present study, effective doses ranged from 5.0 to 9.8 mSv. SPECT/CT revealed high uptake of 99m Tc-TG in all nodular lesions detected according to standard diagnostic methods. There was also agreement between visualization of extranodal lesions using 99m Tc-TG SPECT/CT and standard diagnostic methods in all cases of the brain, neck, chest and abdomen lesions. In our study, the use of 99m Tc-TG SPECT/CT allowed us to detect a bone lesion that was not visualized on CT. This finding was an indication for an additional MRI examination, which confirmed a lymphoma lesion of the humerus. 2 hours after the injection of 99m Tc-TG, the tumor-background ratio reached 3.3 ± 1.2, then decreased to 2.30 ± 1.42 after 4 hours and then did not change significantly, so the optimal time for performing SPECT is 2 hours after the introduction of 99m Tc-TG. Conclusion : 99m Tc-TG is well tolerated by patients and has favorable dosimetric properties. 99m Tc-TG SPECT/CT may become the only method for molecular imaging of lymphoma in patients living in countries and regions with limited or no access to PET.

Comparison of 1-h with 3-h planar 99mTc-pyrophosphate scintigraphy in patients with suspected transthyretin cardiac amyloidosis using SPECT as a reference standard.

The purpose of this study was to examine the diagnostic value of planar 99mTc-pyrophosphate (PYP) imaging at 1 and 3h after tracer administration in patients with suspected transthyretin cardiac amyloidosis (ATTR-CA) using SPECT as a reference standard. We also tested whether blood pool activity of PYP is associated with renal dysfunction. PYP images of 109 consecutive patients with suspected ATTR-CA were retrospectively reviewed. The myocardial PYP uptake was visually graded on a scale of 0 to 3 and quantified with the heart-to-contralateral (H/CL) ratio in accordance with the current expert consensus recommendations. The diagnostic value of planar images for identifying positive PYP SPECT was assessed by a receiver-operating characteristic curve analysis with the area under the curve (AUC). The uptake ratios of the ascending and descending aorta, left atrium, and trapezius muscle divided by the liver uptake were measured on SPECT images and compared to the renal function. A total of 41 patients (38%) had myocardial PYP uptake on SPECT images. In comparison with the visual scores on 1-h anterior planar images, those on 3-h anterior planar images had lower sensitivity (80.5% vs. 97.6%) and higher specificity (86.8% vs. 55.9%) for identifying positive PYP SPECT. The ROC analysis showed that the combination of visual scores on both 1-h and 3-h anterior planar images had significantly higher AUC values in comparison with 1-h anterior planar images alone (0.90 [95% CI 0.83-0.94] vs. 0.83 [95% CI 0.75-0.88]; P < 0.001), which was comparable to the AUC values on 3-h anterior planar images alone (0.88 [95% CI 0.80-0.92]; P = 0.071). In comparison with visual scores on 1-h or 3-h anterior planar images alone, the combination of visual scores and H/CL ratio did not significantly improve the diagnostic value for identifying positive PYP SPECT (P = 0.73 and P = 0.50, respectively). The uptake ratios of ascending aorta/liver, descending aorta/liver, left atrium/liver, and trapezius muscle/liver were not significantly associated with the serum creatinine level or estimated glomerular filtration rate (P > 0.05 for all). In the assessment of ATTR-CA using PYP imaging, visual scores on 3-h anterior planar images for identifying positive PYP SPECT had lower sensitivity and higher specificity in comparison with those on 1-h anterior planar images. The diagnostic value of the visual scores on 1-h and 3-h anterior planar images was not improved by adding the H/CL ratio. Blood pool activity of PYP was not significantly associated with renal dysfunction.

Comparison of reprojected bone SPECT/CT and planar bone scintigraphy for the detection of bone metastases in breast and prostate cancer.

The aim of this study was to compare reprojected bone SPECT/CT (RBS) against planar bone scintigraphy (BS) in the detection of bone metastases in breast and prostate cancer patients. Twenty-six breast and 105 prostate cancer patients with high risk for bone metastases underwent 99mTc-HMDP BS and whole-body SPECT/CT, 1.5-T whole-body diffusion-weighted MRI and 18F-NaF or 18F-PSMA-1007 PET/CT within two prospective clinical trials (NCT01339780 and NCT03537391). Consensus reading of all imaging modalities and follow-up data were used to define the reference standard diagnosis. The SPECT/CT data were reprojected into anterior and posterior views to produce RBS images. Both BS and RBS images were independently double read by two pairs of experienced nuclear medicine physicians. The findings were validated against the reference standard diagnosis and compared between BS and RBS on the patient, region and lesion levels. All metastatic patients detected by BS were also detected by RBS. In addition, three metastatic patients were missed by BS but detected by RBS. The average patient-level sensitivity of two readers for metastases was 75% for BS and 87% for RBS, and the corresponding specificity was 79% for BS and 39% for RBS. The average region-level sensitivity of two readers was 64% for BS and 69% for RBS, and the corresponding specificity was 96% for BS and 87% for RBS. Whole-body bone SPECT/CT can be reprojected into more familiar anterior and posterior planar images with excellent sensitivity for bone metastases, making additional acquisition of planar BS unnecessary.

Quantification of Tc-99m macroaggregated albumin liver perfusion as a predictor of tumor response to intra-arterial therapy with yttrium 90 spheres

Objectives: It remains unclear whether quantifying the pre-therapy tumor Technetium 99m macro aggregated albumin (Tc 99m MAA) localization can accurately predict the response to Yttrium 90 (Y-90) spheres therapy. Present studies are limited and with contradictory results. The aim of this study is to determine if quantification of Tc-99m MAA in hepatic tumor lesion(s) on pretherapy planning nuclear scan can predict the degree of tumor response after radioembolization using Y-90 Spheres. Material and Methods: We retrospectively included patients with primary liver cancers or metastases who were treated with SirSpheres or TheraSpheres. All patients had a Tc-99m MAA scan with an average dose of 5.0mCi injected aseptically in either the right, left, or common hepatic artery. The patients were subsequently transferred for imaging using planar and single-photon emission computed tomography (SPECT) of the abdomen and planar images of the chest. We calculated geometric mean of radiotracer counts in the largest lesion in the lobe to be treated by placing same size region of interest (ROI) around the largest lesion on the anterior and posterior planar images. Subsequently, an irregular ROI around the liver or lobe to be treated were drawn to calculate the geometric mean of counts in the liver. The percent tracer accumulation in the largest lesion was calculated by dividing the geometric mean of counts in the largest lesion by the geometric mean of counts in the liver or lobe and multiplying by 100%. The size of this largest lesion was obtained on the most recent CT or magnetic resonance imaging (MRI) in cm in 2 directions prior to treatment with Y-90 Spheres. The extent of the response to Y-90 Spheres therapy was re-evaluated with 3 months follow-up MRI or CT by measuring the decrease in the largest lesion size. Comparison of the percent Tc-99 MAA count accumulation in the largest lesion on the pre-therapy scan with the reduction in size using anatomic imaging was performed. Results: A total of 30 patients were included (16 hepatocellular carcinoma, eight colorectal, three breast, one neuroendocrine, one cholangiocarcinoma, and one cervical metastases). There were 14 patients in stable disease or progressive disease group (SD/PD gp) and 16 patients in partial response or complete response group (PR/CR gp). The median lesion size was 3.5 cm in the PD/SD gp versus 2.8 cm in the PR/CR gp (P = 0.31). Additionally, the median delivered Y90 Spheres treatment dose was 51.3 mCi in the PD/SD versus 43.2 mCi in the PR/CR gp (P = 0.22). The percent median largest lesion to liver concentration was 21.9% in the PR/CR gp versus 23.3% in the PR/CR gp (P = 0.74). There was no significant difference in percent Tc-99m MAA distribution in the largest liver lesion between the SD/PD gp and the PR/CR gp. Conclusion: The degree of Tc-99m MAA localization in the largest tumor lesion in the liver compared to the remainder of the liver as quantified from planar images does not predict the response to Y-90 spheres therapy.

Phase I Trial of 131I-GMIB-Anti-HER2-VHH1, a New Promising Candidate for HER2-Targeted Radionuclide Therapy in Breast Cancer Patients.

131I-GMIB-anti-human epidermal growth factor receptor type 2 (HER2)-VHH1 is a targeted radionuclide theranostic agent directed at HER2-expressing cancers. VHH1 is a single-domain antibody covalently linked to therapeutic 131I via the linker N-succinimidyl 4-guanidino-methyl-3-iodobenzoate (SGMIB). The phase I study was aimed at evaluating the safety, biodistribution, radiation dosimetry, and tumor-imaging potential of 131I-GMIB-anti-HER2-VHH1 in healthy volunteers and breast cancer patients. Methods: In a first cohort, 6 healthy volunteers were included. The biodistribution of 131I-GMIB-anti-HER2-VHH1 was assessed using whole-body (anterior and posterior) planar images obtained at 40 min and at 2, 4, 24, and 72 h after intravenously administered (38 ± 9 MBq) 131I-GMIB-anti-HER2-VHH1. Imaging data were analyzed using OLINDA/EXM software to determine the dosimetry. Blood and urine samples were obtained over 72 h. In the second cohort, 3 patients with metastatic HER2-positive breast cancer were included. Planar whole-body imaging was performed at 2 and 24 h after injection. Additional SPECT/CT images were obtained after the whole-body images at 2 and 24 h if there was relevant uptake in known cancer lesions. Results: No drug-related adverse events were observed throughout the study. The biologic half-life of 131I-GMIB-anti-HER2-VHH1 in healthy subjects was about 8 h. After intravenous administration, the compound was eliminated from the blood with a 2.5-h half-life. The drug was eliminated primarily via the kidneys. The drug was stable in circulation, and there was no increased accumulation in the thyroid or stomach. The absorbed dose to the kidneys was 1.54 ± 0.25 mGy/MBq, and to bone marrow it was 0.03 ± 0.01 mGy/MBq. SPECT/CT imaging in patients with advanced breast cancer showed focal uptake of 131I-GMIB-anti-HER2-VHH1 in metastatic lesions. Conclusion: Because of its favorable toxicity profile and its uptake in HER2-positive lesions, this radiopharmaceutical can offer new therapeutic options to patients who have progressed on trastuzumab, pertuzumab, or trastuzmab emtansine, given its difference in mode-of-action. A dose escalation is planned in a subsequent phase I/II study to assess the therapeutic window of this compound (NCT04467515).

Differential diagnosis of parkinsonism: a head-to-head comparison of FDG PET and MIBG scintigraphy

[18F]fluorodeoxyglucose (FDG) PET and [123I]metaiodobenzylguanidine (MIBG) scintigraphy may contribute to the differential diagnosis of neurodegenerative parkinsonism. To identify the superior method, we retrospectively evaluated 54 patients with suspected neurodegenerative parkinsonism, who were referred for FDG PET and MIBG scintigraphy. Two investigators visually assessed FDG PET scans using an ordinal 6-step score for disease-specific patterns of Lewy body diseases (LBD) or atypical parkinsonism (APS) and assigned the latter to the subgroups multiple system atrophy (MSA), progressive supranuclear palsy (PSP), or corticobasal syndrome. Regions-of-interest analysis on anterior planar MIBG images served to calculate the heart-to-mediastinum ratio. Movement disorder specialists blinded to imaging results established clinical follow-up diagnosis by means of guideline-derived case vignettes. Clinical follow-up (1.7 ± 2.3 years) revealed the following diagnoses: n = 19 LBD (n = 17 Parkinson’s disease [PD], n = 1 PD dementia, and n = 1 dementia with Lewy bodies), n = 31 APS (n = 28 MSA, n = 3 PSP), n = 3 non-neurodegenerative parkinsonism; n = 1 patient could not be diagnosed and was excluded. Receiver operating characteristic analyses for discriminating LBD vs. non-LBD revealed a larger area under the curve for FDG PET than for MIBG scintigraphy at statistical trend level for consensus rating (0.82 vs. 0.69, p = 0.06; significant for investigator #1: 0.83 vs. 0.69, p = 0.04). The analysis of PD vs. MSA showed a similar difference (0.82 vs. 0.69, p = 0.11; rater #1: 0.83 vs. 0.69, p = 0.07). Albeit the notable differences in diagnostic performance did not attain statistical significance, the authors consider this finding clinically relevant and suggest that FDG PET, which also allows for subgrouping of APS, should be preferred.

Incidental Hydroxyapatite Ocular Implant Uptake on Bone Scan Done for Prostate Cancer Staging: Case Report and Brief Review

A 74-year-old man recently diagnosed with high-risk prostate cancer with high serum prostate specific antigen was referred to nuclear medicine for a technetium-99m-methylene diphosphonate (Tc-99m MDP) bone scan. On delayed three-hour anterior planar image, an unexpected round focus of intense uptake was found overlying the right orbit. Single-photon emission computed tomography/computed tomography localized the uptake to an ocular prosthesis. The hydroxyapatite composition of the ocular implant can be recognized by its bone-like density and its intense accumulation of Tc-99m MDP. Review of the patient’s history revealed remote right eye evisceration secondary to a complication of cataract surgery, consistent with the findings.

Cardio-pulmonary involvement in pulmonary arterial hypertension: A perfusion and innervation scintigraphic evaluation

BackgroundPulmonary arterial hypertension (PAH) is characterized by the right ventricle (RV) remodeling and pulmonary endothelial dysfunction. We studied cardiac perfusion and innervation in PAH with a cadmium-zinc-telluride (CZT) scanner and lung uptake impairment of 123I-metaiodobenzylguanidine (123I-MIBG). MethodsIn 13 patients with newly diagnosed PAH and 11 dilated cardiomyopathies (DCM, for comparative purposes), we assessed early and delayed 123I-MIBG uptake ratios of lung-to-mediastinum (L/M) and heart-to-mediastinum (H/M) on anterior planar images. A quantitative myocardial innervation with 123I-MIBG and perfusion with 99mTc-tetrofosmin using CZT-SPECT was performed. All patients underwent right heart catheterization. ResultsEarly and delayed L/M ratios in PAH were lower than DCM (1.47 ± 0.14 vs 1.98 ± 0.11 and 1.40 ± 0.13 vs 1.83 ± 0.09; P < .001), while early and delayed H/M were impaired but not different (1.73 ± 0.20 vs 1.65 ± 0.18 and 1.73 ± 0.27 vs 1.58 ± 0.19). RV perfusion and early innervation were significantly higher in PAH compared to DCM (68.4 ± 13.4 vs 28.6 ± 4.1 and 58.8 ± 9.3 vs 27 ± 2.2; P < .001); delayed RV innervation was not evaluable. RV/LV perfusion and innervation ratios were significantly related (R = 0.74; P < .0001) and had a significant correlation with clinical, hemodynamic, and morpho-functional parameters, including L/M ratios. ConclusionCardio-pulmonary scintigraphy through a perfusion and innervation study is feasible and may identify pulmonary vascular and RV remodeling, as in PAH.

Pilocarpine effect on dose rate of salivary gland in differentiated thyroid carcinoma patients treated with radioiodine

Although different methods have been suggested on reducing salivary gland radiation after radioiodine administration, an effective preventive or therapeutic measure is still up for debate. The aim of this study was to evaluate the effect of pilocarpine, as a sialagogue drug on the radioiodine content of the salivary gland, and radioiodine-induced symptoms of salivary gland dysfunction. Patients who were referred for radioiodine therapy were randomized into pilocarpine and placebo groups. The patients as well as the nurse who administered the tablets, and the specialist who analyzed the images, were all unaware of the patients' group. Anterior and posterior planar images including that of both the head and neck were obtained 2, 6, 12, 24, and 48 h after the administration of radioiodine in all patients, and round regions of interest were drawn for both left and right parotid glands, with a rectangular region of interest in the region of the cerebrum as background. All patients were interrogated once, 6 months after radioiodine administration, by a phone call for subjective evaluation of symptoms related to salivary gland damage. There was no significant difference between the two groups with regard to the mean age, sex, and initial iodine activity. The geometric mean of background-corrected count per administered dose and acquisition time was calculated for the bilateral parotid glands. This normalized parotid count showed a significant reduction in net parotid count in both groups during the first 48 h after radioiodine administration. However, no significant difference was found between the groups according to the amount and pattern of dose reduction in this time period. This study revealed that pilocarpine had no significant effect on the radioiodine content of parotid glands during the first 48 h after radioiodine administration. No significant difference was found in the incidence of symptoms between the two groups treated with placebo and pilocarpine.

The effect of chewing-gum on dose rate of salivary gland in differentiated thyroid carcinoma patients treated with radioiodine.

Although, different methods have been suggested on reducing salivary gland radiation after radioiodine administration, an effective preventive or therapeutic measure is still debated. To the best of our knowledge this is the second study that aimed to evaluate the effect of chewing-gum as a sialagogue on the radioiodine content of salivary gland, and radioiodine-induced symptoms of salivary gland dysfunction. Twenty-two patients who were referred to radioiodine therapy were randomized into chewing-gum (group A) and control (group B) groups. Anterior and posterior planar images including both head and neck were obtained 2, 6, 12, 24 and 48 hours after the administration of radioiodine in all patients and round regions of interest (ROI) were drawn for both left and right parotid glands with a rectangular ROI in the region of cerebrum as the background. All patients were followed once, 6 months after radioiodine administration via a phone call for subjective evaluation of symptoms related to salivary gland damage. There was no significant difference between the two groups regarding the mean age, gender and initial iodine activity. The geometric mean of background-corrected count per administrated dose and acquisition time was calculated for bilateral parotid glands. This normalized parotid count showed a significant reduction in net parotid count in both groups during the first 48 hours after the radioiodine administration. However, no significant difference was found between the groups according to the amount and pattern of dose reduction in this time period. This study revealed that chewing-gum had no significant effect on the radioiodine content of parotid glands during the first 48 hours after radioiodine administration. Also, no significant difference was found in the incidence of relevant symptoms after 6 months comparing both groups.

Comparison of planar bone scintigraphy and single photon emission computed tomography for diagnosis of active condylar hyperplasia.

The aim of this study was to compare the reliability and correlations with age and gender of two nuclear medicine tests used for diagnosis of active condylar hyperplasia, namely, planar bone scintigraphy versus single photon emission computed tomography (SPECT). This was a descriptive observational study carried out in 61 patients (38 women and 23 men) clinically diagnosed as having facial asymmetry and suspected unilateral condylar hyperplasia. The patients had both planar bone scintigraphy and SPECT diagnostic imaging as well as reference data of the percentage of (99)Tc(m) MDP (methylenediphosphonate) uptake in the condyle, clivus, and fourth lumbar vertebra (L4), respectively, for SPECT and planar scintigraphy calculations. Radioactive counts were measured per region of interest and the respective ratios were calculated. The age range of the patients was 13-50 years (mean ± standard deviation = 21.16 ± 8.75). The two groups were compared by a nonparametric (Mann-Whitney U test. Uptake percentage and delta values had normal distribution and consequently were compared by a Student t test. A total of 61 anterior planar images and 61 SPECT images were compared. Eight patients presented high uptake in planar bone scintigraphy images (13.11%), while 32 patients (52.46%) had high uptake with SPECT. The prevalence of condylar hyperactivity was higher in women than in men both for right condyle (ratio 4:3) and for left condyle (10:1) and the prevalence was significantly higher for the right condyle. The study indicates that SPECT is more sensitive to identify condylar hyperactivity as compared to planar bone scintigraphy in patients with clinical presumptive diagnostic of condylar hyperplasia.

123I-MIBG SPECT for Evaluation of Patients with Heart Failure.

Heart failure (HF) is characterized by activation of the sympathetic cardiac nerves. The condition of cardiac sympathetic nerves can be evaluated by (123)I-metaiodobenzylguanidine ((123)I-MIBG) imaging. Most cardiac (123)I-MIBG studies have relied on measurements from anterior planar images of the chest. However, it has become progressively more common to include SPECT imaging in clinical and research protocols. This review examines recent trends in (123)I-MIBG SPECT imaging and evidence that provides the basis for the increased use of the procedure in the clinical management of patients with HF. (123)I-MIBG SPECT has been shown to be complementary to planar imaging in patients with HF in studies of coronary artery disease after an acute myocardial infarction. Moreover, (123)I-MIBG SPECT has been used in numerous studies to document regional denervation for arrhythmic event risk assessment. For better quantification of the size and severity of innervation abnormalities in (123)I-MIBG SPECT, programs and protocols specifically for (123)I have been developed. Also, the introduction of new solid-state cameras has created the potential for more rapid SPECT acquisitions or a reduction in radiopharmaceutical activity. Although PET imaging has superior quantitative capabilities, (123)I-MIBG SPECT is, for the foreseeable future, the only widely available nuclear imaging method for assessing regional myocardial sympathetic innervation.

A Phase I–II, Open-Label, Multicenter Trial to Determine the Dosimetry and Safety of 99mTc-Sestamibi in Pediatric Subjects

Myocardial perfusion imaging has long been used off label by practitioners attending for children with cardiac aliments. To provide clinicians with evidence-based dosage recommendation, a phase I-II, open-label, nonrandomized, multicenter trial was therefore designed using (99m)Tc-sestamibi in pediatric subjects (registered under www.clinicaltrials.gov identifier no. NCT00162045). Safety and pharmacokinetic data were collected from 78 subjects using either a 1-d imaging protocol (3.7-7.4 MBq/kg, followed by 11.1 MBq/kg) or a 2-d protocol (7.4 MBq/kg for both rest and stress). Anterior and posterior planar images were collected at 15 min, 1.5 h, 4 h, and 8 h. Blood and urine samples were collected at predetermined times. Subjects included 39 children (mean age ± SD, 8.5 ± 2.04 y) and 39 adolescents (mean age ± SD, 13.6 ± 1.39 y). Mean estimated organ-absorbed doses to the upper large intestine, small intestine, gallbladder wall, and lower large intestines were 0.082, 0.043, 0.042, and 0.035 mSv/MBq, respectively. All patients tolerated the radiotracer without serious adverse effects. Significant differences were observed in the liver, upper large intestine contents, and small intestine contents between rest and stress imaging. The effective dose equivalent and effective dose averages were lower in adolescents than younger children (0.011 and 0.019 mSv/MBq, respectively; P < 0.0001). Percentage injected doses (%IDs) corrected for radioactive decay in all dosimetry-evaluable subjects at 15 min and 4 h were 1.9% and 1.2% in the myocardium. Similarly in the lungs, the %ID for all dosimetry-evaluable subjects was 4.9% at 15 min after injection. At rest, the %ID in the liver decreased from a maximum of about 26% at 15 min to less than 9% at 90 min. With stress, values decreased from 15% to 7%, respectively. The estimates of radiation dosimetry, pharmacokinetic parameters, and safety profile in this study population are similar to published studies based on body-mass extrapolations from studies in adults. As such, applying current (99m)Tc-sestamibi dosing regimens for 1- and 2-d protocols based on those extrapolations will result in the expected radiation dose in children and adolescents.

Thymic uptake after high-dose I-131 treatment in patients with differentiated thyroid carcinoma: A brief review of possible causes and management

PurposeTo report five cases of patients diagnosed with differentiated thyroid carcinoma (DTC) with uptake in the thymic area after high-dose treatment with I-131 and to evaluate the potential causes and therapeutic management. MethodsFive cases of young female patients with a mean age of 36.6 years (24–43) who had been treated with a mean dose of 106mCi of I-131 (100–150mCi) showing tracer uptake in the thymic area are reported. An I-131 whole-body scan (131I-WBS) was performed 7 days after therapeutic dose administration to each patient. Anterior and posterior planar images, followed by SPECT/CT of the head, neck and superior mediastinum were acquired in all patients. Thyroglobulin levels were measured with and without hormone replacement therapy in all cases. Samples taken from the superior mediastinum were sent to pathology for analysis, which confirmed the presence of thymic tissue. ResultsTwo patients underwent elective total thymectomy due to the gross characteristics of the gland, local 131-I uptake, and high thyroglobulin levels. The remaining three patients had already undergone thymectomy as part of neck dissection during initial surgery, and no further invasive interventions were therefore performed. Pathological examination revealed no metastases in these five patients. ConclusionsThymus visualization in young patients after administration of therapeutic doses of I-131 seems to be a more common finding than usually thought. Absence of metastasis in the thymus despite high thyroglobulin levels was confirmed in all cases. Based on these results, we suggest that a more expectant and less aggressive therapeutic approach could be used. We also suggest that I-131 therapy for DTC should be considered in classification of the potential causes of true thymic hyperplasia in the subgroup of patients recovering from a stressor.

Efficacy of Thyroid Blockade on Thyroid Radioiodine Uptake in 123I-mIBG Imaging

Although iodinated radiopharmaceuticals usually contain a small quantity of unbound iodine, it is difficult to establish the degree to which thyroid activity on scintigraphic images reflects uptake of free radioiodine. The objective of the present study was to examine the effectiveness of thyroid blockade in subjects undergoing (123)I-meta-iodobenzylguanidine (mIBG) imaging and to estimate the relative contribution of bound and unbound radioiodine to imaging findings. All subjects were participants in prospective trials of (123)I-mIBG cardiac imaging in which pretreatment with thyroid blockade was optional unless locally required. In a pilot project, 15 subjects (6 blocked) had thyroid uptake measured at 4 h using a probe system. Fifteen-minute (early) and 4-h (late) anterior planar chest images that included the thyroid region were visually scored for thyroid uptake (scale of 0-4) in another group of 152 subjects (98 blocked). Quantitative analysis based on thyroid regions of interest was performed on anterior planar images from a further sample of 669 subjects (442 blocked). For all 3 investigations, quantitative comparisons of thyroid uptake were made between the blocked and nonblocked subjects. There was no statistical difference between probe uptake of the 6 blocked and 9 nonblocked subjects. However, in the second series, mean visual score on the late images was significantly lower for blocked than nonblocked subjects (P < 0.001). In the region-of-interest analyses, net thyroid counts were significantly higher on the late images of nonblocked subjects (P < 0.0001), and compared with early images, 87% of subjects who received blockade showed decreased or unchanged counts whereas 75% of nonblocked subjects had increased net thyroid activity. In nonblocked subjects, an estimated 79% of thyroid counts on late images could be attributed to unbound (123)I. On the basis of 3 different methods for assessing thyroid uptake of (123)I, use of thyroid blockade pretreatment in (123)I-mIBG imaging prevents increase of thyroid activity over time because of uptake of unbound (123)I. In most subjects, there is a low level of (123)I-mIBG thyroid activity that probably represents specific uptake in sympathetic nerve terminals.

Additional Detection of Multiple Osteomas in a Patient with Gardner's Syndrome by Bone SPECT/CT.

Familial adenomatous polyposis (FAP) is an autosomal dominant disorder which generally develops numerous polyps in the colon and rectum during the second decade of life [1]. Gardner’s syndrome is a variant of FAP which has multiple osteomas, dental abnormalities, and fibromas, with incidence ranging between 1 in 4,000 and 1 in 40,000, depending on the region [2–5]. We present the case of a 35-year-old man referred to our department for bone scintigraphy who was shown to have multiple colon polyps and nuchal type fibroma. In this patient, planar image showed intensely increased uptakes of bone agent in the maxilla and mandible (Fig. 1a), which are typical findings of Gardner’s syndrome [6, 7]. Single photon emission computed tomography/computed tomography (SPECT/CT) was acquired to accurately identify and locate abnormal uptakes detected on planar images. SPECT/CT showed numerous osteomas in the maxilla and mandible where intense uptakes of bone agent were seen (Fig. 1b-d). Mildly asymmetrical, focally increased uptake in the superomedial aspect of the left orbit on anterior planar image was shown to be a fontal sinus osteoma on SPECT/CT (Fig. 2a). Enhanced sensitivity of detecting lesions of SPECT/CT superior to planar scintigraphy has been reported in previous studies [8, 9]. In this report, additional osteomas of sphenoidal and ethmoidal sinuses, which were not seen on planar scintigraphy, were detected by SPECT/CT (Fig. 2b, c). This case emphasizes that nuclear physicians should be aware of the typical findings of bone scintigraphy for Gardner’s syndrome and also that SPECT/CT could be helpful to diagnose additional lesions not seen on planar images. Fig. 1 A 35-year-old man presented with a history of growing neck mass in the right posterior neck. Surgical excision was performed, and subsequent biopsy revealed the mass as nuchal type fibroma. To rule out Gardner’s syndrome, colonoscopy was performed ... Fig. 2 The focally asymmetrically increased uptake in the left orbit was found out to be an osteoma in left frontal sinus (a). Moreover, SPECT/CT images showed additional, multiple, focally increased uptakes of bone agent in sphenoidal (b) and ethmoidal (c) ...

Fusion of gamma scintigraphic and magnetic resonance images improves the anatomical delineation of radiotracer for the assessment of gastrointestinal transit

This paper describes the use of gamma scintigraphic and magnetic resonance (MR) fusion images for improving the anatomical delineation of orally administered radiotracers used in gastrointestinal (GI) transit investigations. Ten healthy volunteers ingested enteric-coated gelatin capsules containing 4.4 ± 1.1 MBq SmCl3-labelled resin. Four external body markers containing Sm and Gd-DTPA were placed on the left and right lower costal margins and iliac crests of each volunteer. Anterior and posterior planar images were acquired hourly for 9 h, followed by a final single photon emission computed tomography (SPECT) image and subsequent T1-weighted images using a 1.5 T MR system. Coronal scintigraphic images were fused with MR images and assessed for diagnostic information. The fused images revealed a combination of the tissue and organ anatomy with an overlay of the distribution of the tracer. Compared with conventional scintigraphic imaging alone, SPECT-MR fused images improved the localization of spatial and temporal movements of the radiotracer throughout the GI tract. Fusion of SPECT and MR images in conjunction with sequential scintigraphic images improved the assessment of segmental GI transit. These have the potential to provide more accurate diagnostic results and are visually powerful images that would have more widespread acceptance by nonspecialists.

Non coplanar positioning evaluation on stereotactic cranial treatments with a TruebeamTM on board imaging

Purpose/Objective Cranial stereotactic treatments are planned with Volumetric Arctherapy (VMAT) and delivered with an accelerator TrueBeam (STX-HD)/Varian. Several arcs are defined with three iscocentric treatment table rotations. The images used to control the positioning are obtained only with the kV imager OBI (On Board Imaging). The accelerator room does not contain any additional inroom imagers. Each table rotation is validated with specific planar kV images. Material/methods The patient positioning is assessed with the help of a CB-CT compared to the reference treatment planning CT. An automatic table displacement is performed when set-up errors appear. This position being defined as a reference; two additional anterior and posterior planar images are performed. Three markers are placed on the tabletop (MT), on the mask at the front isocenter projection (MI) and on the patient's skin (MP) through a hole above an orbit. Positions of the 3 markers in the orthonormal coordinate system are recorded (L–R and H–F directions). The markers positions are then compared to those measured at the other treatment table rotations. Results The evaluation involved 1094 measurements of 360 images and 15 different patients. The images comparison is carried out for three markers in the two orthogonal directions. The measurement error, due to the use of a graphic rule, is estimated to be 0.2 mm. The evaluation is performed for each marker (MT, MI, MP). The maximum deviation is, respectively, 0.9, 0.9, 4.2 mm. The average deviation is, respectively, 0.4, 0.3, 0.4 mm. The standard deviation is, respectively, 0.3, 0.2, 0.5 mm. Conclusion Knowing that no additional in-room images are used, comparing the position of every marker between the images obtained at table rotations, relative to the reference position, ensures the traceability of each non-coplanar position. The three markers provide additional information on the three elements (table, patient, mask) related to the target. The results are consistent with the mechanical precision of the TrueBeam accelerator and its treatment table. We finally validate the safety margin PTV set to 3 mm.

SU-E-CAMPUS-I-04: Creation and Quantification Analysis of a Simulated SPECT Database Using the 4D-MOBY Phantom for Imaging Applications

Purpose: To develop a database of realistic animal SPECT simulations.Simulations were performed using a wholebody mouse model testing several realistic preclinical situations and compared against real small animal imaging acquisitions. Methods: The GATE Monte Carlo toolkit was used for modeling a small animal SPECT system. The camera has a hexagonal parallel hole collimator and a ∼1.6 mm spatial resolution.The 4D digital MOBY phantom was used in order to model mouse anatomy and activity distribution.Planar and SPECT scans for the biodistribution of the commonly used 99mTc based radiopharmaceuticals (MIBI, MDP and HMPAO) were modeled. Resulting simulated data were reconstructed using the QSPECT opensource software for SPECT reconstruction with a 10% energy window. Results: Simulations were executed in the GateLab grid resulting to: a) MDP bone scan biodistribution (anterior posterior planar images), b) Whole body mouse Sestamibi biodistribution, c) 99mTc HMPAO (whole body scan), d) 2 scans for HMPAO biokinetics within the brain (mouse and rat), and e) 99mTc radiolabled magnetic nanoparticles imaging with the MOBY phantom (the activity distribution was extracted from real data). Quantitative analysis was performed in several regions of interest. Simulated results were compared against real data and theoretical values available in the literature.The HMPAO brain biokinetics of both the mouse and rat brains were compared in order to investigate the impact of the brain size on detecting various brain structures.In the mouse model the brain was observed as a single entity, while in the case of the rat brain model structures were distinguished. Conclusion: GATE provides precise physics modeling based on the Geant4 code, while the 4D MOBY phantom can produce realistic imaging data, against which other imaging systems, reconstruction and correction techniques can be compared and standardized. To our knowledge this is the first small animal SPECT database with corresponding imaging data of realistic preclinical situations.