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Aim: CT images can identify structural and opacity alterations of the lungs while nuclear medicine's lung perfusion studies show the homogeneity (or lack of) of blood perfusion on the organ. Therefore, the use of SPECT/CT in lung perfusion scintigraphies can help physicians to assess anatomical and functional alterations of the lungs and to differentiate between acute and chronic disease. Objective: To develop a computer-aided methodology to quantify the total global perfusion of the lungs via SPECT/CT images and to compare these results with parenchymal alterations obtained in CT images. Methods: 39 perfusion SPECT/CT images collected retrospectively from the Nuclear Medicine Facility of Botucatu Medical School's Clinics Hospital in São Paulo, Brazil, were analyzed. Anatomical lung impairments (emphysema, collapsed and infiltrated tissue) and the functional percentage of the lungs (blood perfusion) were quantified from CT and SPECT images, with the aid of the free, open-source software 3D Slicer. The results obtained with 3D Slicer (3D-TGP) were also compared to the total global perfusion of each patient's found on their medical report, obtained from visual inspection of planar images (2D-TGP). Results: This research developed a novel and practical methodology for obtaining lungs' total global perfusion from SPECT/CT images in a semiautomatic manner. 3D-TGP versus 2D-TGP showed a bias of 7% with a variation up to 67% between the two methods. Perfusion percentage showed a weak positive correlation with infiltration (p = 0.0070 and ρ = 0.43) and collapsed parenchyma (p = 0.040 and ρ = 0.33). Conclusions: This research brings meaningful contributions to the scientific community because it used a free open-source software to quantify the lungs blood perfusion via SPECT/CT images and pointed that the relationship between parenchyma alterations and the organ's perfusion capability might not be so direct, given compensatory mechanisms. [ABSTRACT FROM AUTHOR]

Objective: Molecular imaging of prostate-specific membrane antigen (PSMA) inhibitors has become a favorite for prostate cancer (PCa). This study aimed to estimate the dosimetry and the preliminary clinical application of the [99mTc]Tc-HYNIC-PSMA-XL-2, which is a novel imaging tracer invented by our team that can specifically targets PSMA for PCa and its metastases. Methods: The single-photon emission computed tomography (SPECT) whole-body (WB) planar images were collected on 6 patients at 0.5, 1.0, 2.0, 4.0 and 8.0 h after 99mTc-PSMA-XL-2 injection, respectively. The SPECT/computed tomography (CT) scan was carried out immediately following the WB planar image scan performed after 2.0 h. The volumes of interest (VOIs) of the bladder, heart wall, intestines, kidneys, liver, lungs, and spleen were segmented in the SPECT/CT images. VOIs of the salivary glands and the whole body were drawn in SPECT planar images. The dosimetry toolkit was used to process the data and project the SPECT/CT images onto planar images. The dosimetry analysis was performed using the IDAC-Dose dosimetry software. Furthermore, other PCa patients were enrolled to study the preliminary clinical application of [99mTc]Tc-HYNIC-PSMA-XL-2. Results: The clearance of [99mTc]Tc-HYNIC-PSMA-XL-2 is primarily by the hepatobiliary and intestinal system, due to its lipophilic characteristic. The effective half-life of [99mTc]Tc-HYNIC-PSMA-XL-2 is about 3.90 h. High absorbed doses were observed in the salivary glands (1.93E-02 ± 3.88E-03 mSv/MBq), kidneys (1.63E-02 ± 7.32E-03 mSv/MBq) and spleen (1.21E-02 ± 2.64E-03 mSv/MBq). The total body effective dose was 4.84E-03 ± 9.30E-05 mSv/MBq. The preliminary clinical case indicated that [99mTc]Tc-HYNIC-PSMA-XL-2 SPECT/CT could detect the primary prostate lesion, lymph node and bone metastases comprehensively. Conclusion: [99mTc]Tc-HYNIC-PSMA-XL-2 is a safe SPECT/CT tracer, which can detect prostate malignant lesions without interference from the bladder. In addition, the malignant lesions of the lymph node and bone of PCa patients also can be detected efficiently. [ABSTRACT FROM AUTHOR]

Purpose: To retrospectively investigate whether the standard uptake value (SUV) of 99mTc-bone single-photon emission computed tomography (SPECT)/CT could be useful for predicting prosthetic joint infection (PJI) at the hip. Patients and methods: We analyzed the cases of 37 patients with a suspected PJI at the hip who underwent 99mTc-bone SPECT/CT and surgical intervention with pathological and bacterial examinations. We divided the cases into those with and those without a causative bacterium detected in a surgical specimen, i.e., the positive bacterial culture (PBC) group (n = 17) and negative bacterial culture (NBC) group (n = 20). Cases with neutrophilic infiltration of surgical specimen comprised the positive neutrophilic infiltration (PINF) group (n = 18) and those without INF comprised the non-neutrophilic infiltration (NINF) group (n = 19). Quantitative analyses were performed using maximum SUVs and peak SUVs of blood-pool (BP) phase images (SUVmaxBP and SUVpeakBP) and late (LT)-phase images (SUVmaxLT and SUVpeakLT). Results: Regarding the bacterial cultures, there were significant differences between the PBC and NBC groups in SUVmaxBP (5.26 ± 1.49 vs. 4.21 ± 1.15, respectively; p = 0.019), SUVpeakBP (4.89 ± 1.32 vs. 3.87 ± 1.06, p = 0.012), SUVmaxLT (16.10 ± 6.36 vs. 11.67 ± 4.95, p = 0.026), and SUVpeakLT (14.58 ± 5.83 vs. 10.49 ± 4.31 p = 0.036). Regarding neutrophilic infiltration, there were significant differences between the PINF and NINF groups in SUVmaxBP (5.18 ± 1.48 vs. 4.24 ± 1.19, p = 0.047) and SUVpeakBP (4.78 ± 1.32 vs. 3.92 ± 1.10, p = 0.043). Conclusion: An SUV analysis of 99mTc-bone SPECT/CT is a useful method to differentiate a PJI at the hip from non-infection. [ABSTRACT FROM AUTHOR]

Objective: The feasibility of tracer production of 99mtechnetium (Tc)-prostate-specific membrane antigen (PSMA)—I&S sterile cold kit, imaging with single photon emission tomography/computed tomography (SPECT/CT), and 99mTc-PSMA-radioguided robot-assisted laparoscopic radical prostatectomy (99mTc-PSMA-RG-RALRP) technique for lymph node (LN) dissection of primary prostate cancer (PCa) patients were evaluated prospectively. Methods: Fifteen primary PCa patients with intermediate- or high-risk score according to D'Amico risk stratification who had PSMA receptor affinity with Ga-68 PSMA-11 PET/CT were enrolled. After 99mTc-PSMA-I&S injection and SPECT/CT imaging, 99mTc-PSMA-RG-RALRP with DaVinci XI robotic platform and laparoscopic gamma probe were performed. Radioactive rating of resected tissue was compared with post-operative histopathology. Physiological and pathological uptakes of organs and tissues for both imaging modalities were compared. Results: Physiological radiotracer distribution was similar for both imaging modalities. PCa lesions were much more visible on PET/CT. Metastatic LNs could not be visualized with SPECT/CT. Eighteen of 297 totally dissected LNs were metastatic, which were exactly the same with per-operative probe counts with sensitivity, specificity, accuracy, and negative and positive predictive value of all 100%. The median follow-up was 23.5 ± 4.6 months. tPSA reduction was > 98%. The 2.5 years biochemical recurrence-free survival, PCa-specific treatment-free survival and overall survival rates were 86,7%, 66,7% and 100%, respectively. Conclusion: Tc-99 m-PSMA-RG-RALRP is a promising technique for extended pelvic lymph node dissection (ePLND) during robotic surgery, which may shorten the operation time and reduce complication risks. If LN metastases is detected during surgery with PSMA-targeted probe, it may be an early indicator of PCa-spesific treatment planning. Tc-99 m-PSMA-I&S SPECT/CT is not as successful as Ga-68 PSMA-11 PET/CT for diagnosis of primary PCA lesions or LN metastases. [ABSTRACT FROM AUTHOR]

Objective: 123I metaiodobenzylguanidine (MIBG) scintigraphy is a useful tool for the diagnosis of pheochromocytomas (PHEOs), but some PHEOs are difficult to differentiate from cortical adenoma (CA) or normal adrenal uptake by visual evaluation alone. A new semi-quantitative analysis using 123I MIBG SPECT/CT is thus expected. Herein, we introduce the tumor-to-liver count ratio (T/L) and the tumor-to-muscle count ratio (T/M). Methods: We examined the cases of 21 patients with PHEOs (10 males, 11 females; age 24–80, median 61 years) and 23 patients with CA (15 males and 8 females, age 30–78, median 58 years). The visual scoring based on 123I MIBG planar images (planar score) and SPECT images (SPECT score) was used as the conventional evaluation. Using 123I MIBG SPECT/CT findings, we calculated the semi-quantitative values of the count ratio using the maximum or mean count of the tumor and the liver or muscle as the reference organ (T/Lmax, T/Lmean, T/Mmax and T/Mmean). Each evaluation of the PHEOs and CAs was compared, and the diagnosing performance was evaluated based on an ROC analysis. Results: The area under curve (AUC) values were as follows: the planar score, 0.833; SPECT score, 0.813; T/Lmax, 0.986; T/Lmean, 0.975; T/Mmax, 0.955; and T/Mmean, 0.933. The AUC for T/Mmax was significantly higher than those of the planar score, and SPECT score by ROC analysis (p < 0.01 each). Conclusion: The semi-quantitative value of 123I MIBG SPECT/CT is more useful than the conventional visual evaluation for differentiating PHEOs from CAs. [ABSTRACT FROM AUTHOR]

Aim: To investigate the relationship between epicardial adipose tissue (EAT) volume and distribution and the parameters of global cardiac and regional left atrial (LA) sympathetic activity in patients with atrial fibrillation (AF). Methods and results: The data of the 45 consecutive patients scheduled for an index catheter ablation (CA) for AF were analyzed. Total and peri-atrial EAT volumes were measured by cardiac CT. Parameters of global cardiac sympathetic activity and discrete sympathetic regions around LA were assessed by 123I-mIBG SPECT/CT. The patients were followed up for AF recurrences assessment during 12 months after CA. A total of 133 (mean per patient 2.96 ± 1.07) discrete 123I-mIBG uptake areas (DUAs), corresponding to typical anatomical locations of LA ganglionated plexi (GP), were identified. Peri-atrial EAT volume was associated with the number of DUAs (regression estimate, 5.1 [95% CI, 0.3–9.9], p = 0.03). There was no statistically significant association between either total or peri-atrial EAT volumes and risks of AF recurrence. The washout rate (WR) was associated with reduced risk of AF recurrence (HR = 0.95; 95% CI 0.92–0.99; p = 0.01), while left ventricular (LV) myocardium 123I-mIBG summed defect score (SDS) was linked to increased hazards of AF recurrence (HR = 1.04; 95% CI 1.01–1.08; p = 0.03). Conclusion: Peri-atrial EAT volume is associated with regions of sympathetic activity corresponding to typical anatomical locations of LA GP. The WR was associated with reduced risk of AF recurrence while LV myocardial SDS was linked to increased hazards of AF recurrence. [ABSTRACT FROM AUTHOR]

Objective: 123I metaiodobenzylguanidine (MIBG) scintigraphy is a useful tool for the diagnosis of neuroblastoma (NB). MIBG uptake is correlated with norepinephrine transporter expression; hence, it is expected that high-MIBG tumors would be more highly differentiated and have a better prognosis than those with lower expression. We have introduced a method of assessing MIBG accumulation semi-quantitatively using SPECT/CT fusion images. The purpose of this study was to evaluate the relationship of 123I MIBG uptake measured by semi-quantitative values of SPECT/CT and early relapse of NB. Methods: We studied the cases of 11 patients (5 males and 6 females, age 5–65 months, median age 20 months) with histopathologically proven NB between April 2010 and March 2015. The early-relapse group was defined as patients who had relapsed within 3 years after the first 123I MIBG SPECT/CT exam. Other patients were classified as the delay-relapse group. Uptake of MIBG was evaluated using the count ratio of tumor and muscles. T/Mmax and T/Mmean were defined as follows: T/Mmax = max count of tumor/max count of muscle, T/Mmean = mean count of tumor/mean count of muscle. Results: The average T/Mmean values of the early-relapse group and delay-relapse group were 2.65 ± 0.58 and 7.66 ± 2.68, respectively. The T/Mmean values of the early-relapse group were significantly lower than those of delay-relapse group (p < 0.05). The average T/Mmax of the early-relapse group and delay-relapse group were 8.86 ± 3.22 and 16.20 ± 1.97, respectively. There was no significant difference in T/Mmax values between the two groups. Conclusions: Low 123I MIBG uptake using semi-quantitative SPECT/CT analysis was correlated with early relapse of NB. [ABSTRACT FROM AUTHOR]

Objective: For 99mTc-sestamibi parathyroid single photon emission computed tomography/computed tomography (SPECT/CT), the traditional full-arc 360° acquisition technique has been suggested but not the theoretically low tissue-attenuated anterior 180° method. We aimed to compare the diagnostic performances and target-to-background ratios of anterior 180° and 360° SPECT/CT imaging. Methods: Ninety-nine patients who underwent 99mTc-sestamibi scintigraphy and received a surgical–pathological diagnosis of parathyroid adenoma or hyperplasia were enrolled. The SPECT/CT reconstructed images with anterior 180° and full-arc 360° data were interpreted by two physicians using a scoring scale, and the lesions were semi-quantified using target-to-background ratios for both image sets. Results: In total, 113 abnormal parathyroid lesions were identified on the SPECT/CT images. The agreements of interpretation between the two image sets and readers were very good (κ value: 0.83–1.00). The accuracies of summative interpretation for the anterior 180° and full-arc 360° SPECT/CT were 83.04% and 82.46%, respectively. The target-to-background ratios were significantly higher for the anterior 180° than the full-arc 360° images (P < 0.01). Conclusions: The anterior 180° SPECT/CT technique, a time-saving method, can provide satisfactory diagnostic performance and superior lesion contrast compared with the full-arc 360° SPECT/CT technique in 99mTc-sestamibi parathyroid imaging. [ABSTRACT FROM AUTHOR]

Objective: This retrospective study investigated the performance of whole-body bone scintigraphy combined with SPECT/CT and established a grading diagnostic criterion for bone metastases. Methods: We summarized signs of whole-body bone imaging combined with SPECT in nuclear medicine and CT signs of corresponding parts. Then we established a diagnostic criterion for bone metastases by using whole-body bone scintigraphy combined with local SPECT/CT. The criterion is classified into five grades. 120 patients with a total of 141 lesions underwent whole-body bone scintigraphy and SPECT/CT. Two reviewers read the images according to the diagnostic criterion. With pathological diagnosis as the "gold standard", the diagnostic efficacy for bone metastases and the diagnostic agreement between the two reviewers were analyzed to validate the feasibility of the criterion. Diagnostic effectiveness was expressed in terms of sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. Results: The diagnostic accuracy of the two reviewers was 90.1% and 92.9% respectively, sensitivity was both 100%, specificity was 41.7% and 58.3%, positive predictive value was 89.3% and 92.1%, and negative predictive value was both 100%. The kappa value of the diagnostic tests performed by the two reviewers on whole-body bone scintigraphy combined with SPECT/CT was 0.919 (P < 0.001). Conclusion: The grading diagnostic criterion for bone metastases by whole-body bone scintigraphy combined with SPECT/CT has high diagnostic accuracy and good consistency between reviewers, but the specificity was still low even with SPECT/CT. [ABSTRACT FROM AUTHOR]

Background: Despite recent technological advances allowing for quantitative single-photon emission computed tomography (SPECT), quantitative SPECT has not been widely used in the clinical practice of osteoporosis. The aim of this study is to evaluate the feasibility of quantitative bone SPECT/CT for measuring lumbar standard uptake value (SUV) in patients with different bone-mineral density (BMD), and investigate the correlation between SUV measured with 99mTc-methylene diphosphonate (MDP) SPECT/CT and BMD assessment by dual-energy X-ray absorptiometry (DXA).Methods: A retrospective analysis of 62 cases 99mTc-MDP whole-body bone imaging and local lumbar SPECT/CT tomography were performed. According to the results of dual-energy X-ray bone density examination, they were divided into normal group, osteopenic group, and osteoporosis group. The raw SPECT data were reconstructed using flash3D which includes attenuation correction, scatter compensation, and collimator resolution recovery, SPECT images from this algorithm were calibrated for SUV analysis. Comparing difference of lumbar SUV in different BMD subjects, and investigating the correlation between lumbar SUV and BMD. Data were analyzed by one-way ANOVA and Pearson regression analysis using SPSS 17.0 software.Results: The maximum SUV (SUVmax) and mean SUV (SUVmean) of L1-L4 vertebral in 62 subjects were 7.39 ± 1.84 and 4.90 ± 1.27, respectively. The average BMD was 0.85 ± 0.15 (g/cm2), and the average CT value was 145.88 ± 53.99 (HU). The SUVmax, SUVmean, BMD, and CT values of the lumbar spine were statistically significantly different among the three groups (F = 24.089, 30.501, 94.847, 30.241, all p < 0.001), and the osteopenic group was significantly lower than the normal group (all p < 0.001), the osteoporosis group was significantly lower than the normal group and the osteopenic group (all p < 0.001). Lumbar SUVmax, SUVmean, and BMD were significantly negatively correlated with age (r = - 0.328 to - 0.442, all p < 0.05), and positively correlated with body weight and CT value (r = 0.299-0.737, all p < 0.05), but no significant correlation with height (r = 0.006-0.175, all p > 0.05). Lumbar SUVmax and SUVmean increased significantly with the increase of BMD (r = 0.638, 0.632, p < 0.001).Conclusion: The SUV of lumbar spine in 99mTc-MDP bone SPECT/CT was significantly different among subjects with different BMD, and the SUV was positively correlated with BMD. These findings justify that quantitative bone SPECT/CT is an applicable tool for clinical quantification of bone metabolism in osteoporosis patients. [ABSTRACT FROM AUTHOR]

Background: The in vivo expression of the prostate-specific membrane antigen (PSMA) can be investigated using the SPECT-suitable tracer 99mTc-MIP-1404. We investigated the performance of 99mTc-MIP-1404 PSMA SPECT/CT in the detection of PSMA-positive tumor lesions in patients suffering from biochemical recurrence of prostate cancer presenting with serum levels of the prostate-specific antigen (PSA) below 1 ng/mL.Methods: We retrospectively analyzed 99mTc-MIP-1404-SPECT/CT scans of 50 patients (25 with low PSA levels between > 0.5 and 1 ng/mL and 25 with very low PSA levels between 0.2 and 0.5 ng/mL) that had undergone whole-body planar scintigraphy and SPECT/CT of the thorax, abdomen and pelvis 3-4 h p.i. of 691 ± 72 MBq 99mTc-MIP-1404. All datasets were evaluated for the presence and location of PSMA-positive tumor lesions, in which maximal standardized uptake values (SUVmax) were also measured. Based on the results of the quantitative evaluation as well as on biochemical and histological parameters, predictive factors for a positive 99mTc-MIP-1404 scan result were determined. The influence of 99mTc-MIP-1404 PSMA SPECT/CT on further therapy planning was assessed, based on the decision-making of the interdisciplinary tumor board.Results: Pathological 99mTc-MIP-1404 uptake was detected in a total of 25 patients (50%). In the very low PSA subgroup, detection rates of PSMA-positive lesions suggestive of tumor recurrence were 44%, in the low-PSA subgroup 56%. Gleason scores ≥ 8 and the presence of antiandrogen deprivation therapy were further significant predictors of pathological 99mTc-MIP-1404 uptake. This was paralleled by significantly higher lesional SUVmax patients with PSA levels > 0.5 ng/mL and Gleason scores ≥ 8 compared to those without these two features. Changes in therapeutic strategy following MIP-1404 imaging were recommended by the interdisciplinary tumor board in 25/50 of patients.Conclusion: 99mTc-MIP-1404 PSMA-SPECT/CT demonstrated a high performance in detecting PSMA-positive lesions suggestive of tumor recurrence in patients with biochemical recurrence of prostate cancer and low and very low serum PSA levels. Results from MIP-1404 PSMA SPECT/CT have therapeutic impact in one-half of the patients examined by this technology. [ABSTRACT FROM AUTHOR]

Purpose: Epiphora is commonly caused by a relative or complete occlusion in the lacrimal drainage system (LDS), principally a nasolacrimal duct obstruction (NLDO). Dacryoscintigraphy (DSG), an extensively assessed imaging technique in diagnosing its abnormalities, can provide only planar images, according to which it needs to be improved. Our aim was to evaluate clinical utility of simultaneous DSG and single-photon emission computed tomography/computed tomography (SPECT/CT) combined with computed tomographic dacryocystography (CT-DCG) in the evaluation of LDS.Methods: Dynamic imaging with DSG was performed, and tracer radioactivity was detected by a gamma camera. Successively, SPECT/CT images of the involved region were gained, followed by CT-DCG, during which a contrast medium was syringed into the affected LDS, and finally contrast CT scans were obtained again from the same region.Results: Fifty-seven patients, mean age 54.25 (± 18.26) years all with unilateral NLDO and 32 control subjects, all with patent LDS, mean age 49.88 (± 18.61) years were evaluated in the study. Delayed outflow of tearing eyes was exposed to DSG compared to the fellow and control eyes. The highest value for sensitivity was observed for SPECT/CT, followed by CT-DCG and DSG techniques, while combining DSG with SPECT/CT, DSG with CT-DCG, and SPECT/CT with CT-DCG, the sensitivity increased to 96.49%, 92.98%, and 94.73%, respectively.Conclusions: Although DSG is a sensitive nuclear medicine method, it only provides useful clinical data when simultaneously supplemented with SPECT/CT and CT-DCG trials as they jointly can offer valuable information about the localization of an abnormality and verify stenosis or obstruction. [ABSTRACT FROM AUTHOR]

Introduction: In any radiotherapy, the absorbed dose needs to be estimated based on two factors, the time-integrated activity of the administered radiopharmaceutical and the patient-specific dose kernel. In this study, we consider the uncertainty with which such absorbed dose estimation can be achieved in a clinical environment.Methods: To calculate the total error of dose estimation we considered the following aspects: The error resulting from computing the time-integrated activity, the difference between the S-value and the patient specific full Monte Carlo simulation, the error from segmenting the volume-of-interest (kidney) and the intrinsic error of the activimeter.Results: The total relative error in dose estimation can amount to 25.0% and is composed of the error of the time-integrated activity 17.1%, the error of the S-value 16.7%, the segmentation error 5.4% and the activimeter accuracy 5.0%.Conclusion: Errors from estimating the time-integrated activity and approximations applied to dose kernel computations contribute about equally and represent the dominant contributions far exceeding the contributions from VOI segmentation and activimeter accuracy. [ABSTRACT FROM AUTHOR]

Objective: Radio-guided sentinel node (SN) biopsy is a standard method used in the treatment of early breast cancer. Single photon emission computed tomography with computed tomography (SPECT/CT) has been commonly used for SN detection. SPECT/CT adds precise anatomical information of SN sites, and it is reported that more SNs may be detectable on SPECT/CT than on planar imaging. We here investigate which breast cancer patients have benefited from SPECT/CT over planar imaging.Methods: A total of 273 breast cancer patients including 80 with ipsilateral breast tumor relapse (IBTR) underwent both multiple-view planar imaging and SPECT/CT for SN detection. The number of SNs, the patients who had benefitted from SPECT/CT, and the SN procedure failure rate were compared between SPECT/CT and planar imaging. Factors influencing the visualization of para-sternal and ipsilateral level II, III nodes, and contralateral axillary nodes were also analyzed using logistic regression analysis.Results: The number of hot spots did not differ between SPECT/CT and multiple-view planar imaging. Eight contaminated patients and 52 patients with visualized extra-level I axillary nodes benefited from identifying precise anatomical sites. Even though radioactive nodes could be harvested in most (192/193) of the non-IBTR patients (7/8 in non-SN visible patients), no radioactive nodes could be found during surgery in 11 of 80 IBTR patients. Axillary surgery (dissection) increased the visualization of para-sternal and level II, III axillary nodes, and previous irradiation increased the visualization of contralateral axillary nodes.Conclusion: Multiple-view planar imaging was equivalent to SPECT/CT for depicting hot nodes for radio-guided SN detection in breast cancer. SPECT/CT was useful when precise anatomical information was necessary, especially regarding sentinel lymph nodes other than ipsilateral axilla. Logistic regression analysis revealed that axillary surgery (dissection) increased the visualization of para-sternal and level II, III axillary nodes, and the only relevant factor influencing visualization of contralateral axillary SNs was previous radiation to the breast. [ABSTRACT FROM AUTHOR]

Objective: Our aim of this research was to determine the value of SPECT/CT with 99mTc-HYNIC-TOC for evaluation of the pancreatic masses which were suspected as neuroendocrine neoplasms and follow-up of patients with pancreatic neuroendocrine neoplasms.Methods: We retrospectively analyzed 184 patients who performed 99mTc-HYNIC-TOC SPECT/CT. All the patients were divided into two groups: one for assessment of diagnostic efficiency for pancreatic suspected masses (n = 140) and another for monitoring recurrence after surgery (n = 44). The image findings acquired at 2 h postinjection were compared to final diagnoses from pathological results and clinical follow-up. Then, the correlation between ratios of tumor-to-background (TBR) and tumor grade was analyzed.Results: In group 1, 95/140 (67.9%) patients were confirmed as neuroendocrine neoplasms including 85 neuroendocrine tumors and 10 neuroendocrine carcinomas. Patient-based analysis showed that the sensitivity, specificity and accuracy of diagnosing neuroendocrine neoplasms with SPECT/CT were 81.1, 84.4 and 82.1%. There was significant difference of TBRs among G1, G2 and G3 (F = 3.175, P = 0.048). In group 2, 22/44 (50.0%) patients occurred metastasis mainly in liver. The sensitivity, specificity and accuracy of monitoring recurrence were 87.0, 100 and 93.2%.Conclusions: 99mTc-HYNIC-TOC SPECT/CT is a reliable method of diagnosing and monitoring of pancreatic neuroendocrine neoplasms, especially neuroendocrine tumors. [ABSTRACT FROM AUTHOR]

Purpose: To develop a method for automated detection of highly integrated sites in SPECT images using bone information obtained from CT images in bone scintigraphy.Methods: Bone regions on CT images were first extracted, and bones were identified by segmenting multiple regions. Next, regions corresponding to the bone regions on SPECT images were extracted based on the bone regions on CT images. Subsequently, increased uptake regions were extracted from the SPECT image using thresholding and three-dimensional labeling. Last, the ratio of increased uptake regions to all bone regions was calculated and expressed as a quantitative index. To verify the efficacy of this method, a basic assessment was performed using phantom and clinical data.Results: The results of this analytical method using phantoms created by changing the radioactive concentrations indicated that regions of increased uptake were detected regardless of the radioactive concentration. Assessments using clinical data indicated that detection sensitivity for increased uptake regions was 71% and that the correlation between manual measurements and automated measurements was significant (correlation coefficient 0.868).Conclusion: These results suggested that automated detection of increased uptake regions on SPECT images using bone information obtained from CT images would be possible. [ABSTRACT FROM AUTHOR]

Objective: To determine the added value of CT over planar and SPECT-only imaging in the diagnosis of musculoskeletal infection using 99mTc-UBI 29-4.Materials and Methods: 184 patients with suspected musculoskeletal infection who underwent planar and SPECT/CT imaging with 99mTc-UBI 29-41 were included. Planar, SPECT-only and SPECT/CT images were reviewed by two independent analysts for presence of bone or soft tissue infection. Final diagnosis was confirmed with tissue cultures, surgery/histology or clinical follow-up.Results: 99mTc-UBI 29-41 was true positive in 105/184 patients and true negative in 65/184 patients. When differentiating between soft tissue and bone infection, planar + SPECT-only imaging had a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 95.0, 74.3, 84.8, 91.3 and 86.9%, respectively, versus 99.0, 94.5, 92.5, 98.5 and 94.5% for SPECT/CT. SPECT/CT resulted in a change in reviewers' confidence in the final diagnosis in 91/184 patients. Inter-observer agreement was better with SPECT/CT compared with planar + SPECT imaging (kappa 0.87, 95% CI 0.71-0.85 versus kappa 0.81, 95% CI 0.58-0.75).Conclusion: Addition of CT to planar and SPECT-only imaging led to an increase in diagnostic performance and an improvement in reviewers' confidence and inter-observer agreement in differentiating bone from soft tissue infection. [ABSTRACT FROM AUTHOR]

Rationale: Myocardial perfusion SPECT is a commonly performed, well established, clinically useful procedure for the management of patients with coronary artery disease. However, the attenuation of photons from myocardium impacts the quantification of infarct sizes. CT-Attenuation Correction (AC) potentially resolves this problem. This contention was investigated by analyzing various parameters for infarct size delineation in a cardiac phantom model.Methods: A thorax phantom with a left ventricle (LV), fillable defects, lungs, spine and liver was used. The defects were combined to simulate 6 infarct sizes (5-20% LV). The LV walls were filled with 100120 kBq/ml 99mTc and the liver with 10-12 kBq/ml 99mTc. The defects were filled with water of 50% LV activity to simulate transmural and non-transmural infarction, respectively. Imaging of the phantom was repeated for each configuration in a SPECT/CT system. The defects were positioned in the anterior as well as in the inferior wall. Data were acquired in two modes: 32 views, 30 s/view, 180° and 64 views, 15 s/view, 360° orbit. Images were reconstructed iteratively with scatter correction and resolution recovery. Polar maps were generated and defect sizes were calculated with variable thresholds (40-60%, in 5% steps). The threshold yielding the best correlation and the lowest mean deviation from the true extents was considered optimal.Results: AC data showed accurate estimation of transmural defect extents with an optimal threshold of 50% [non attenuation correction (NAC): 40%]. For the simulation of non-transmural defects, a threshold of 55% for AC was found to yield the best results (NAC: 45%). The variability in defect size due to the location (anterior versus inferior) of the defect was reduced by 50% when using AC data indicating the benefit from using AC. No difference in the optimal threshold was observed between the different orbits.Conclusion: Cardiac SPECT/CT shows an improved capability for quantitative defect size assessment in phantom studies due to the positive effects of attenuation correction. [ABSTRACT FROM AUTHOR]

Purpose: We developed a method of image data projection of bone SPECT into 3D volume-rendered CT images for 3D SPECT/CT fusion. The aims of our study were to evaluate its feasibility and clinical usefulness.Methods: Whole-body bone scintigraphy (WB) and SPECT/CT scans were performed in 318 cancer patients using a dedicated SPECT/CT systems. Volume data of bone SPECT and CT were fused to obtain 2D SPECT/CT images. To generate our 3D SPECT/CT images, colored voxel data of bone SPECT were projected onto the corresponding location of the volume-rendered CT data after a semi-automatic bone extraction. Then, the resultant 3D images were blended with conventional volume-rendered CT images, allowing to grasp the three-dimensional relationship between bone metabolism and anatomy. WB and SPECT (WB + SPECT), 2D SPECT/CT fusion, and 3D SPECT/CT fusion were evaluated by two independent reviewers in the diagnosis of bone metastasis. The inter-observer variability and diagnostic accuracy in these three image sets were investigated using a four-point diagnostic scale.Results: Increased bone metabolism was found in 744 metastatic sites and 1002 benign changes. On a per-lesion basis, inter-observer agreements in the diagnosis of bone metastasis were 0.72 for WB + SPECT, 0.90 for 2D SPECT/CT, and 0.89 for 3D SPECT/CT. Receiver operating characteristic analyses for the diagnostic accuracy of bone metastasis showed that WB + SPECT, 2D SPECT/CT, and 3D SPECT/CT had an area under the curve of 0.800, 0.983, and 0.983 for reader 1, 0.865, 0.992, and 0.993 for reader 2, respectively (WB + SPECT vs. 2D or 3D SPECT/CT, p < 0.001; 2D vs. 3D SPECT/CT, n.s.). The durations of interpretation of WB + SPECT, 2D SPECT/CT, and 3D SPECT/CT images were 241 ± 75, 225 ± 73, and 182 ± 71 s for reader 1 and 207 ± 72, 190 ± 73, and 179 ± 73 s for reader 2, respectively. As a result, it took shorter time to read 3D SPECT/CT images than 2D SPECT/CT (p < 0.0001) or WB + SPECT images (p < 0.0001).Conclusions: 3D SPECT/CT fusion offers comparable diagnostic accuracy to 2D SPECT/CT fusion. The visual effect of 3D SPECT/CT fusion facilitates reduction of reading time compared to 2D SPECT/CT fusion. [ABSTRACT FROM AUTHOR]

Objective: Cine average CT (CACT) and interpolated average CT (IACT) have been proposed to improve attenuation correction (AC) for PET/CT in oncologic and cardiac studies. This study aims to evaluate their effectiveness on myocardial perfusion SPECT/CT using computer simulation and physical phantom experiments. Methods: We first simulated normal male with 99mTc-sestamibi distribution using digital XCAT phantom with respiratory motion amplitudes of 2, 3, and 4 cm. Average activity and attenuation maps represented static SPECT and CACT, while the attenuation maps of end-inspiration and end-expiration represented two helical CTs (HCTs), respectively. Sixty noise-free and noisy projections were simulated over 180° using an analytical parallel-hole projector. We then filled 673 MBq 99mTc into an anthropomorphic torso phantom with normal heart or heart with a defect which placed on a programmable respiratory platform to model various respiratory amplitudes. Sixty projections were acquired over 180° using a clinical SPECT/CT scanner. The CACT, standard HCT, and 2 HCTs at extreme phases were acquired. Interpolated CT phases were generated between them using affine plus b-spline registration, and IACT was obtained by averaging the interpolated phases and the 2 original extreme phases for both simulation and phantom experiments. Projections were reconstructed with AC using CACT, IACT, and HCTs, respectively. Polar and 17-segment plots were analyzed by relative difference (RD) of the uptake. Two regions-of-interest (ROI) were drawn on the defect and background area to obtain the intensity ratio (IR). Results: No substantial difference was observed on the polar plots generated from different AC methods, while the quantitative RD measurements showed that SPECTCACT were most similar to the original phantom, followed by SPECTIACT, with RDmax <8 and <10% in the simulation study. The RD of SPECTHCTs deviated from the original phantom and SPECTCACT in various segments, with RDmax of 19.76 and 16.68% in the simulation and phantom experiment, respectively. The IR of SPECTHCTs fluctuated more from the truth for higher motion amplitude. Conclusions: Both CACT-AC and IACT-AC reduced respiratory artifacts and improved quantitation in myocardial perfusion SPECT as compared to HCT-AC. The use of IACT further reduced the radiation dose. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to compare preoperative SPECT/CT with gamma-probe and methylene blue-dye (MBD) in the identification of sentinel lymph node (SLN) in early stage endometrial cancer. Methods: 40 stage-I EC patients (66.7 ± 9.7 years) underwent preoperative lymphoscintigraphy. After about 3 h from Tc-99m-albumin nanocolloid cervical injection, all patients underwent SPECT/CT study. MBD was injected into the cervix just before surgery under general anesthesia. All patients underwent SLN biopsy, hysterectomy, bilateral salpingo-oophorectomy, and radical regional lymphadenectomy. SPECT/CT findings were compared to those of gamma-probe and MBD techniques. Results: In 2 patients no nodal migration was observed, neither with MBD nor radiotracer. Detection rate of at least one SLN was 90% (36/40 patients) with SPECT/CT, 88% (35/40) intra-operatively with gamma-probe and 80% (32/40) with MBD. Only in 7/40 patients a bilateral migration was obtained with all considered modalities. In particular, bilateral detection was achieved in 26 patients with SPECT/CT, in 24 with gamma-probe and in 10 patients with MBD. The concordance site between SPECT/CT and intraoperative gamma-probe was 73% (29/40 patients: 2 without migration, 21 bilateral and 6 monolateral SLNs); while concordance site with MBD was found in 40% (16/40: 8 bilateral, 6 monolateral SLNs, 2 without SLNs). Overall, 628 LNs were dissected (mean 18 LNs per patient). The median number of SLNs removed was 2 (mean 2.5 per patient). Out of 91 SLNs: 43 were "hot and blue (HB)", 10 were blue only and 38 were hot only. LN metastases rate was 16%: 9/90 SLNs (7 HB, 2 hot only) were positive for metastases in 6 patients. Four non-SLNs were found positive in 3 patients, and all presented concomitant positive SLNs. False negative rate was 0%. Conclusions: SPECT/CT had the highest detection rate and achieved the highest rate of bilateral mapping, compared to gamma-probe and MDB. SPECT/CT had moderate concordance with gamma-probe, and it can help the intraoperative detection of SLNs providing important information about their anatomic location. [ABSTRACT FROM AUTHOR]

Objective: The purpose of the present study was to prepare isostructural Tc-99m- and Re-188-folate-Gly-Gly-Cys-Glu (folate-GGCE), and to evaluate the feasibility of their use for folate receptor (FR)-targeted molecular imaging and as theranostic agents in a mouse tumor model.Methods: Folate-GGCE was synthesized using solid-phase peptide synthesis and radiolabeled with Tc-99m or Re-188. Radiochemical characterization was performed by radio-high-performance liquid chromatography. The biodistribution of Tc-99m-folate-GGCE was studied, with or without co-injection of excess free folate, in mice bearing both FR-positive (KB cell) and FR-negative (HT1080 cell) tumors. Biodistribution of Re-188-folate-GGCE was studied in mice bearing KB tumors. Serial planar scintigraphy was performed in the dual tumor mouse model after intravenous injection of Tc-99m-folate-GGCE. Serial micro-single photon emission computed tomography/computed tomography (SPECT/CT) studies were performed, with or without co-injection of excess free folate, in the mouse tumor model after injection of Tc-99m-folate-GGCE or Re-188-folate-GGCE.Results: The radiolabeling efficiency and radiochemical stability of Tc-99m- and Re-188-folate-GGCE were more than 95 % for up to 4 h after radiolabeling. Uptake of Tc-99m-folate-GGCE at 1, 2, and 4 h after injection in KB tumor was 16.4, 23.2, and 17.6 % injected dose per gram (%ID/g), respectively. This uptake was suppressed by 97.4 % when excess free folate was co-administered. Tumor:normal organ ratios at 4 h for blood, liver, lung, muscle, and kidney were 54.3, 25.2, 38.3, 97.8, and 0.3, respectively. Tumor uptake of Re-188-folate-GGCE at 2, 4, 8, and 16 h after injection was 17.4, 21.7, 24.1, and 15.6 %ID/g, respectively. Tumor:normal organ ratios at 8 h for blood, liver, lung, muscle, and kidney were 126.8, 21.9, 54.8, 80.3, and 0.4, respectively. KB tumors were clearly visualized at a high intensity using serial scintigraphy and micro-SPECT/CT in mice injected with Tc-99m- or Re-188-folate-GGCE. The tumor uptake of these molecules was completely suppressed when excess free folate was co-administered.Conclusion: Isostructural Tc-99m- and Re-188-folate-GGCE showed high and FR-specific uptake by tumors and generally favorable tumor:normal organ ratios. The tumor targeting capabilities of Tc-99m- and Re-188-folate-GGCE were clearly evident on serial imaging studies. This isostructural pair may have potential diagnostic and theranostic applications for FR-positive tumors. [ABSTRACT FROM AUTHOR]

Background: Functional imaging can help clinicians assess the individual response of advanced nonsquamous non-small cell lung cancer (NSCLC) to chemoradiation therapy plus bevacizumab. Our purpose is to investigate the ability of Tc-3PRGD single photon emission computed tomography/computed tomography (SPECT/CT) in predicting the early response to treatment. Methods: Patients with advanced nonsquamous NSCLC diagnosed by histological or cytological examination were imaged with Tc-3PRGD SPECT/CT at 3 time points: 1-3 days before the start of treatment (SPECT1), 40 Gy radiotherapy with 2 cycles of chemotherapy plus bevacizumab (SPECT2) and 4 weeks after chemoradiotherapy plus bevacizumab (SPECT3). The images were evaluated semiquantitatively by measuring the tumor to non-tumor ratio (T/N) and calculating the percentage change in T/N ratio. Short-term outcome was assessed by the treatment response evaluation according to the Response Evaluation Criteria in Solid Tumors criteria as: complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD). Patients were divided two groups: responders (CR and PR) and nonresponders (SD and PD). To determine a threshold for percent reduction in T/N ratios, receiver-operating characteristic (ROC) curve analysis was used. Patients were grouped again based on the threshold of P1 (the change percentage from SPECT1 to SPECT2) and P2 (the change percentage from SPECT1 to SPECT3): P1 responders and P1 nonresponders; P2 responders and P2 nonresponders. Patients were followed up starting 4 weeks after completion of therapy and then every 3 months for the first 2 years and every 6 months after 2 years. OS of P1 responders, P1 nonresponders, P2 responders and P2 nonresponders was estimated and graphically illustrated using the Kaplan-Meier method and the log-rank test was used to test the null hypotheses of equal OS in subgroups of patients. Results: A total of 28 patients completed all imaging and treatment. All primary lung tumors were well visualized on SPECT1. The mean T/N ratio of SPECT1 in responders and nonresponders was not statistically different (2.73 ± 0.59 vs. 2.59 ± 0.52, p > 0.05). At SPECT2 and SPECT3, the mean T/N ratios were both lower in the responders compared with the nonresponders and had statistical significance ( p < 0.05). P1 and P2 in the responders was larger than the nonresponders with significant difference (P1: 34.18 ± 21.55 % vs. 9.02 ± 14.02 %, p < 0.05; P2: 53.02 ± 15.50 % vs. 7.74 ± 37.95 %, p < 0.05). The optimal threshold of P1 that can discriminate between P1 responders and P1 nonresponders was greater than 25.9 % reduction, and that of P2 that can discriminate between P2 responders and P2 nonresponders was 34.0 % reduction. The area under the ROC curve (AUC) of P1 and P2 for determining residual disease was 0.856 and 0.909, respectively; but there was no statistical significance between them ( p > 0.05). There was a significant difference for OS between P1 responders and P1 nonresponders ( p < 0.05), and also for OS between P2 responders and P2 nonresponders ( p < 0.05). But there was no difference between the P1 responders and P2 responders ( p > 0.05), or between the P1 nonresponders and P2 nonresponders ( p > 0.05). Conclusion: A Tc-3PRGD SPECT/CT after two cycles of chemoradiotherapy plus bevacizumab can predict patients who will have a better response to treatment and survival. [ABSTRACT FROM AUTHOR]

Objective: Although SPECT/CT systems have been used for sentinel lymph node (SLN) imaging, few studies have focused on optimization of attenuation correction (AC) and scatter correction (SC). While SLNs could be detected in conventional planar images, they sometimes do not appear in SPECT/CT images. The purpose of this study was to investigate the optimal AC and SC and to improve the detectability of SLNs in examinations using SPECT/CT systems. Materials and methods: The study group consisted of 56 female patients with breast cancer. In SPECT/CT imaging, four kinds of images were created with and without AC and SC; namely, AC−SC−, AC+SC−, AC−SC+ and AC+SC+. Five nuclear medicine physicians interpreted the planar and SPECT/CT images with five grades of confidence levels (1-5). The detection rate was calculated as the number of patients whose average confidence levels of interpretation were more than 4, divided by the total number of patients. Results: The confidence level of interpretation and the detection rate provided by the planar images were 4.76 ± 0.49 and 94.6 %, respectively. In SPECT/CT imaging, the AC+SC− provided the best detection rate (confidence level of interpretation, 4.81 ± 0.38; detection rate, 98.2 %), followed by the AC−SC− (4.70 ± 0.55, 89.3 %), and the AC−SC+ (4.39 ± 1.2, 78.6 %). The lowest values were obtained for the AC+SC+ (4.36 ± 1.22, 78.6 %). Regarding the confidence levels of interpretation, significant differences were observed between AC+SC− and AC−SC−, AC+SC− and AC+SC+, AC+SC− and AC−SC+, and between planar images and AC+SC+ ( P = 0.0021, 0.0009, 0.0013, and 0.0056, respectively). Conclusions: When SPECT/CT was used, AC improved the detection of SLNs. SC caused disappearance of a faint SLN in some cases and should not be performed. [ABSTRACT FROM AUTHOR]

Abundant expression of somatostatin receptors (SSTR) is frequently identified in differentiated neuroendocrine tumors and may serve as potential target for diagnostic imaging and treatment. This article discusses the 'theranostic approach' of SSTR-targeting compounds including an overview of its role for diagnosis, staging and restaging, discussing its way to being established in clinical routine, and giving an outlook about further potentially relevant developments. [ABSTRACT FROM AUTHOR]

Objective: To examine yttrium-90 distribution 1 and 72 h following its injection into a knee joint in patients with rheumatoid arthritis (RA). Methods: In 14 RA patients we injected yttrium-90 into the affected knee joint using lateral approach. To assess the radioisotope distribution in the joint, the superimposed sequential SPECT and CT imaging was performed 1 and 72 h after the injection. We analyzed the percentage of radioisotope distribution in three predefined compartments of the knee joint (lower, upper medial, upper lateral). Results: After 1 and 72 h, the mean percentage distributions were, respectively, 7.14 and 23.07 % in lower; 21.42 and 15.38 % in upper medial, and 71.42 and 61.53 % in upper lateral compartment. The percentage of isotope deposition did not change significantly with time in any of the compartments (all p > 0.26). The deposition of isotope, both at 1 and 72 h, was significantly greater in upper lateral compartment, where the injection was performed, than in all other compartments (all p < 0.05). Conclusions: Using the SPECT/CT hybrid method, we proved that the majority of isotope is located at the compartment adjacent to the injection. Two injections targeting different compartments might improve the clinical efficacy of the procedure. [ABSTRACT FROM AUTHOR]

Objective: The aim of the study was to evaluate the usefulness of Tc-pertechnetate whole body scan (WBS) with neck and chest SPECT/CT for detection of post-surgical thyroid remnant and metastasis in differentiated thyroid cancer (DTC) patients. Methods: Fifty-six post total thyroidectomy patients were included. All patients were prospectively imaged with Tc-pertechnetate WBS with neck and chest SPECT/CT before I ablation. The post-ablative I WBS with SPECT/CT was performed at 5-7 days after receiving I. Both scans were directly compared to determine the concordance of sites and number of remnant and metastasis. Results: Overall per-patient analysis, the percentage of concordance between two scans was 96.4 %. In thyroid bed, lymph node, lung and bone subgroups, the percentage of concordance between two scans was 96.4, 92.9, 98.2 and 100 %, respectively. All of them show good correlation with unweighted kappa between 0.7 and 1. Overall per-lesion analysis, the percentage of concordance between two scans was 84 %. In thyroid bed, lymph node, lung and bone subgroups, the percentage of concordance between two scans was 89.5, 55, 82.6 and 50 %, respectively. Conclusions: Pre-ablative pertechnetate WBS with neck and chest SPECT/CT has good correlation for the detection of post-surgical thyroid remnant, cervical node and discrete lung nodule metastasis as compared to I WBS with SPECT/CT per-patient basis. Because I therapeutic activity is desired base on metastatic site and less concerning about the number of lesions, pre-ablative Tc-pertechnetate WBS with SPECT/CT was a good alternative tool to avoid radioiodine stunning in post-surgical DTC patients. [ABSTRACT FROM AUTHOR]

Objective: The goal of our study was to determine if lymph node activity could be visualized using a hybrid single-photon emission computed tomography/computed tomography (SPECT/CT) scanner with two commonly used colloidal lymphatic radiotracers-Tc-antimony sulfide colloid (ASC) and Tc-filtered sulfur colloid (FSC) in the setting of low-stage non-small cell lung cancer (NSCLC). Methods: Patients undergoing CT-guided percutaneous lung biopsies for clinically suspected early-stage lung cancer were randomized to peri-lesional injection of 37 MBq (0.5 mL) of either ASC or FSC. SPECT/CT of the thorax was performed at either 1, 2, or 3 h post-injection. The images were reviewed to determine if lymph node activity separate from the injection site could be identified. Results: 24 patients were included. Lymph node activity was identified in 50 % of patients. A total of 15 lymph nodes with activity were visualized including 5 ipsilateral hilar, 6 ipsilateral mediastinal, and 4 distant locations. No contralateral mediastinal or hilar activity was visualized. There was a tendency to improved visualization with ASC and the longer 3 h wait time. Most patients also demonstrated significant pleural, tracheobronchial, and/or systemic activity. Conclusions: SPECT/CT imaging can demonstrate lymph node activity separate from the injection site in at least some low-stage NSCLC patients with a perilesional injection of Tc nanocolloid tracers. Further investigation into the role of pre-operative lymphoscintigraphy with SPECT/CT in patients with lung cancer is warranted. [ABSTRACT FROM AUTHOR]

Objective: To investigate the potential role of Tc-99m depreotide (Tc-DEPR) in the preoperative lymph node (N) staging of non-small-cell lung cancer (NSCLC). Methods: Sixty-one patients with NSCLC at the potentially operable stage were enrolled and underwent scintigraphy before surgery ( n = 56) or mediastinoscopy ( n = 5). Imaging was performed with a hybrid single photon emission computed tomography/computed tomography (SPECT/CT) system. Depreotide uptake in N stations was evaluated visually and semi-quantitatively and compared to histology. Quantification was carried out in attenuation-corrected SPECT slices. Different sites of normal uptake were used as a reference for comparison with lesional uptake. Receiver operating characteristic analysis was employed to identify the most preferable reference area and the cut-off best discriminating disease-free from disease-involved lymph nodes. Results: With reference to 53 Ν1 hilar and 147 Ν2/Ν3 sampled stations, sensitivity of scintigraphy by visual interpretation was 100 and 94 %, specificity 43 and 59 % and accuracy 55 and 67 %, respectively. No patient was down-staged, but 52 % were incorrectly up-staged and 44 % were misclassified as inoperable. Compared to scintigraphy, preoperative contrast-enhanced diagnostic CT demonstrated lower sensitivity (36 % for hilar and 73 % for N2/N3 stations), higher specificity (79 and 75 %) and similar accuracy (70 and 75 %). Regarding the ultimate N-stage and the prediction of surgical disease, diagnostic CT was wrong in 51 and 34 % of cases. Dichotomy of quantitative scintigraphic data by the use of certain N-to-spine ratio cut-offs resulted in a significant increase of specificity (76 % for hilar and 89 % for N2/N3 stations), while sensitivity remained high (82 % in both circumstances) and accuracy for Ν2/Ν3 stations was substantially improved (88 %). By this quantitative approach, misclassifications as to the N-stage and patient operability (25 and 16 %) were considerably less than that of visual Tc-DEPR and diagnostic CT interpretations. Conclusion: Tc-99m depreotide SPECT/CT seems to have a role in the N-staging of NSCLC, mainly because of its high sensitivity and negative predictive value. Quantification of uptake can improve specificity, at a low cost of sensitivity. If F-18 fluoro-deoxyglucose positron emission tomography is not available, this method may be used as a surrogate to conventional staging modalities. [ABSTRACT FROM AUTHOR]

Rationale and objectives: As spreading integrated SPECT/CT scanners, reconstruction method based on three-dimensional ordered-subset expectation maximization (3D-OSEM) with attenuation correction (AC) using an X-ray CT image (CTAC) is easily available in brain imaging. For quantitative cerebral blood flow (CBF) measurements, however, the accuracy of this method has not been fully evaluated clinically. To validate this new algorithm, we sequentially studied quantitative PET-CBF and SPECT-CBF measurements in the same healthy volunteers and compared CBF values. Methods: Ten healthy subjects underwent quantitative PET-CBF and SPECT-CBF measurements on the same day. PET-CBF data were obtained by the intravenous injection of O-15 water and the quantitative IMP-ARG method followed. Three types of SPECT images were reconstructed: (1) filtered back projection (FBP) with Chang’s AC (FBP + Chang’s AC), (2) 3D-OSEM with Chang’s AC (3D-OSEM + Chang’s AC), and (3) 3D-OSEM with CTAC (3D-OSEM + CTAC). The mean CBF difference, the linearity, and the correlation between the PET-CBF and SPECT-CBF values were compared among the SPECT reconstruction algorithms. Results: The mean SPECT-CBF values of all the algorithms were significantly lower in the pons ( P = 0.000–0.007) and higher in the frontal lobe ( P = 0.002–0.022). All the SPECT-CBF values were significantly correlated with the PET-CBF values ( r = 0.749–0.829, P < 0.001). The SPECT-CBF values obtained using the 3D-OSEM + CTAC method showed the best regression with the PET-CBF values. Conclusion: The present clinical study validated accuracy of CBF image reconstructed by the 3-D OSEM method with CTAC and the integrated SPECT/CT system. [ABSTRACT FROM AUTHOR]

Hybrid imaging, such as SPECT/CT, is used in routine clinical practice, allowing coregistered images of the functional and structural information provided by the two imaging modalities. However, this multimodality imaging may mean that patients are exposed to a higher radiation dose than those receiving SPECT alone. Objectives: The study aimed to determine the radiation exposure of patients who had undergone SPECT/CT examinations and to relate this to the Background Equivalent Radiation Time (BERT). Methods: 145 SPECT/CT studies were used to estimate the total effective dose to patients due to both radiopharmaceutical administrations and low-dose CT scans. The CT contribution was estimated by the Dose-Length Product method. Specific conversion coefficients were calculated for SPECT explorations. Results: The radiation dose from low-dose CTs ranged between 0.6 mSv for head and neck CT and 2.6 mSv for whole body CT scan, representing a maximum of 1 year of background radiation exposure. These values represent a decrease of 80-85 % with respect to the radiation dose from diagnostic CT. The radiation exposure from radiopharmaceutical administration varied from 2.1 mSv for stress myocardial perfusion SPECT to 26 mSv for gallium SPECT in patients with lymphoma. The BERT ranged from 1 to 11 years. Conclusions: The contribution of low-dose CT scans to the total radiation dose to patients undergoing SPECT/CT examinations is relatively low compared with the effective dose from radiopharmaceutical administration. When a CT scan is only acquired for anatomical localization and attenuation correction, low-dose CT scan is justified on the basis of its lower dose. [ABSTRACT FROM AUTHOR]

Objective: To comparatively assess two techniques, radiocolloid SPECT/CT lymphoscintigraphy and interstitial MR lymphography using SPIO and gadoxetate disodium, in animal models. Materials and methods: We used twenty one 8-week-old male nude mice of strain BALB/c Slc-nu/nu, weighing 23-27 g. The 4.7-T MRI equipment was used to detect the SNs. T2*WI of gradient-echo sequences was acquired sequentially up to 24 h after administering SPIO, ferucarbotran. T1WI was acquired sequentially up to 80 min after administering gadoxetate disodium. Tc-phytate SPECT/CT lymphoscintigraphy was taken at 30 min after the injection to detect the SNs using animal-dedicated whole-body SPECT/CT hybrid scanner. The injection was submucosally performed in the right tongue margin of each mouse. Reading performances concerning SN visualization and its quality on interstitial MR lymphogram and SPECT/CT lymphoscintigram were performed by 3 radiologists. Results: The SN intensities were 0.43 for the right, 0.61 for the left at 30 min after ferucarbotran injection, with gradual decrease in intensity, and 1.43 for the right, 1.33 for the left at 10 min after gadoxetate disodium injection with a fast decrease in intensity. The base value of 1.0 was at pre-examination. The mean numbers of lymph nodes visualized were 4.00 nodes for on SPECT/CT lymphoscintigram and 2.0 for interstitial MR lymphogram. There was a statistically significant difference in the mean scores between SPECT/CT lymphoscintigraphy and interstitial MR lymphography (two factor mixed design with repeated measures on one factor: p < 0.0002). Conclusions: In our comparative study using mice, the results of radiocolloid SPECT/CT lymphoscintigraphy were superior to those of interstitial MR lymphography, while both SPIO and gadoxetate disodium have a potential of being employed for sentinel node navigation surgery by interstitial MR lymphography in the head and neck region. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to elucidate the regional differences between brain perfusion single photon emission computed tomography (SPECT) images reconstructed with a uniform attenuation correction using Chang's method (AC-Chang) and a non-uniform attenuation correction with CT using SPECT/CT (AC-CT). Methods: SPECT images of a phantom with and without head holder were obtained, and reconstructed images of AC-Chang and AC-CT were compared. Twenty-eight consecutive patients with brain disease examined by SPECT/CT brain perfusion imaging were selected, and images were reconstructed with AC-Chang and AC-CT. The AC-Chang and AC-CT reconstructed images were then compared by voxel-based analysis using three-dimensional stereotactic surface projections. Results: Counts in the frontal area of the AC-Chang phantom image with head holder were higher than those in the posterior area. Counts in the frontal area of the AC-Chang clinical images were significantly higher than those in the AC-CT images, while the counts in the margin of the frontal lobe and posterior margin of the parietal, occipital cortices and cerebellum of the AC-Chang images were significantly lower. Relative frontal perfusion was 5.0% higher and relative cerebellar perfusion was 4.6% lower in the AC-Chang images relative to the AC-CT images, on average. Conclusion: We demonstrated the frontal dominant hyper-perfusion and parieto-occipital and cerebellar hypo-perfusion in brain SPECT images reconstructed with AC-Chang compared to those reconstructed with AC-CT. We suggest that to obtain an accurate attenuation-corrected brain perfusion SPECT image, attenuation correction by Chang's method is inadequate. [ABSTRACT FROM AUTHOR]

Objective: A recombinant annexin A5 with the N-terminal extension of six histidine residues was labeled with Tc(I)-tricarbonyl ion to produce the Tc-labeled annexin A5, referred to Tc(I)-his-annexin A5. We have explored the agent as an effective imaging probe for in vivo detecting the apoptosis of internal tissue subjected with high radiation doses in a γ-irradiated mouse model. Methods: [Tc(CO)(OH)] was prepared and taken to directly label his-annexin A5. The radiochemical purity of Tc(I)-his-annexin A5 after size-exclusion separation was measured by HPLC. The binding affinity of Tc(I)-his-annexin A5 to apoptotic cells was assessed using 20 Gy-irradiated Jurkat T cells. The effectiveness of Tc(I)-his-annexin A5 as an imaging probe to detect the internal tissue apoptosis was assessed by biodistribution study and nanoSPECT/CT using the animal model of C57BL/6J mice conducted with 10 Gy γ irradiation. Results: The radiochemical purity of Tc(I)-his-annexin A5 could attain ≥95%. The binding affinity of Tc(I)-his-annexin A5 to the 20 Gy-irradiated Jurkat cells was found to be ca. 20-fold higher than that to the sham-irradiated cells. In the animal imaging study, the splenic uptake of Tc(I)-his-annexin A5 for the 10 Gy-irradiated mice showed from ca. 3-fold to 5-fold higher than those of the sham-irradiated mice from 45 to 165 min postinjection. The corresponding intestinal uptake showed from ca. 2-fold to 3-fold higher during the same period of time postinjection. The biodistribution study demonstrated the organ uptakes comparable with the imaging results. The apoptotic extents of the spleen and the intestine from the SPECT/CT imaging were correlated with an immunohistochemical staining assay for caspase 3 active form fragment. Conclusion: This work is the first study to demonstrate that Tc(I)-his-annexin A5 is a potential clinical imaging agent for detecting radiation-induced tissue apoptosis in an animal model. [ABSTRACT FROM AUTHOR]

Objective: The coronary artery calcium (CAC) score and myocardial perfusion imaging can now be detected simultaneously using a hybrid SPECT/CT camera. However, there has been little evaluation on the relationship between stress-induced ischemia and coronary artery calcification in a Japanese population. The aim of this study was to investigate the relationship between these parameters and to elucidate the diagnostic value of the CAC score as an adjunct to myocardial perfusion imaging (MPI) for the assessment of coronary artery disease (CAD) in an intermediate-risk population. Methods: We retrospectively analyzed 105 patients (63% men, mean age 71 years) with CAD or suspected CAD who underwent MPI using SPECT/CT. CAC scanning was performed using a SPECT/CT camera. Results: There was a significant difference in the CAC score between patients with ischemia ( n = 42) and those without ischemia ( n = 63) (1353 ± 1524 vs. 332 ± 554, p < 0.01). The frequency of ischemic MPI determined by summed difference score tended to be higher in patients with high CAC (CAC = 0; 0.8 ± 1.3 vs. CAC > 1000; 3.0 ± 2.0). Higher age is related roughly with higher CAC score with no statistical significance ( r = 0.1) (<60 years old; 200 ± 692, vs. >80 years old; 1258 ± 1546, ns). The location of calcification was not related to the ischemic area. In a population with a predominately intermediate likelihood of CAD, a calcium score of zero has a possibility of excluding inducible ischemia on MPI. In part, ischemic MPI is associated with a high likelihood of subclinical atherosclerosis as detected by CAC. Conclusion: Hybrid SPECT/CT might be useful for diagnostic assessment and coronary artery with known or suspected CAD. [ABSTRACT FROM AUTHOR]

Yttrium-90 (Y-90) selective internal radiation therapy (SIRT) is increasingly used to treat inoperable hepatocellular carcinoma. We describe two patients where hepatic falciform ligament Technetium-99m-macroaggregated albumin (Tc-99m-MAA) activity was identified on single photon emission computed tomography with integrated low-dose CT (SPECT/CT) scan during pre-therapy planning, and the steps taken to prevent radiation dermatitis. The first patient underwent prophylactic coil embolization of the patent hepatic falciform artery; the second patient underwent super-selective infusion of Y-90 resin microspheres to avoid the patent hepatic falciform artery. The incidence of falciform ligament Tc-99m-MAA activity detected on SPECT/CT at our institution is 10%. Tc-99m-MAA SPECT/CT scan provides valuable diagnostic information for treatment planning prior to Y-90 SIRT. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the value of SPECT/CT in radionuclide arthrogram (RNA) for the assessment of mechanical loosening of hip and knee prostheses. Method: A retrospective audit of 117 RNA SPECT/CTs evaluated by a single reader--40 hips, (1 hemiarthroplasty) and 77 knees (12 unicompartmental). The detection of any radiotracer within the bone/prosthetic interface was deemed positive for loosening. The operative assessment of 29 hip and 44 knee prosthetic joints was known and used as the gold standard. A subsequent blinded reassessment of the planar images was performed and compared with the SPECT/CT results for 26 of the 29 hip and 42 of the 44 knee prostheses. Results: The respective SPECT/CT versus planar results were as follows: hips--acetabular cup: sensitivity: 73 versus 0%; specificity: 71 versus 100%; positive predictive value: 62% versus indeterminate; negative predictive value: 80% versus 72% ( p = 0.0044). Hips--femoral component: sensitivity: 78 versus 63%; specificity: 90 versus 94%; positive predictive value: 78 versus 83%; negative predictive value: 90 versus 85% ( p = 0.2482). Knees--femoral component: sensitivity: 75 versus 17%; specificity 63 versus 97%; positive predictive value: 43 versus 67%; negative predictive value: 87 versus 74% ( p = 0.0001). Knees--tibial component: sensitivity: 86 versus 63%; specificity: 86 versus 76%; positive predictive value: 55 versus 38%; negative predictive value: 97 versus 90% ( p = 0.6831). Conclusion: For evaluation of mechanical loosening of the hip prosthesis SPECT/CT was significantly better than planar scanning for the acetabular cup, but not for the femoral stem. For evaluation of the knee prosthesis, a significant improvement was noted using SPECT/CT for the femoral component, and although superior results were also noted for the tibial component, statistical significance was not reached. Taking into account the limitations of this retrospective audit, the value of using RNA SPECT/CT appeared to lie in the exclusion of mechanical loosening. [ABSTRACT FROM AUTHOR]

Objective: Previous studies have demonstrated the feasibility of targeting lymphoma lesions with somatostatin receptor binding agents, mainly with In-111-pentetreotide. In the present work another somatostatin analog, Tc-99m depreotide, is investigated. Methods: One-hundred and six patients, 47 with Hodgkin's (HL) and 59 with various types of non-Hodgkin's lymphoma (NHL), were imaged with both Tc-99m depreotide and Ga-67 citrate. Planar whole-body and single photon emission tomography/low resolution computerized tomography (SPECT/CT) images were obtained. A total of 142 examinations were undertaken at different phases of the disease. Depreotide and gallium findings were compared visually and semi-quantitatively, with reference to the results of conventional work-up and the patients' follow-up data. Results: In most HL, intermediate- and low-grade B-cell, as well as in T-cell NHL, depreotide depicted more lesions than Ga-67 and/or exhibited higher tumor uptake. The opposite was true in aggressive B-cell NHL. However, there were notable exceptions in all lymphoma subtypes. During initial staging, 93.3% of affected lymph nodes above the diaphragm, 100% of inguinal nodes and all cases with splenic infiltration were detected by depreotide. On the basis of depreotide findings, 32% of patients with early-stage HL were upstaged. However, advanced HL and NHL cases were frequently downstaged, due to low sensitivity for abdominal lymph node (22.7%), liver (45.5%) and bone marrow involvement (36.4%). Post-therapy, depreotide detected 94.7% of cases with refractory disease or recurrence. Its overall specificity was moderate (57.1%). Rebound thymic hyperplasia, various inflammatory processes and sites of unspecific uptake were the commonest causes of false positive findings. The combination of depreotide and gallium enhanced sensitivity (100%), while various false positive results of either agent could be avoided. Conclusion: Except perhaps for early-stage HL, Tc-99m depreotide as a stand-alone imaging modality has limited value for the initial staging of lymphomas. Post-therapy, however, depreotide scintigraphy seems useful in the evaluation of certain anatomic areas, particularly in non-aggressive lymphoma types. The combination with Ga-67 potentially enhances sensitivity and specificity. If fluorodeoxyglucose positron emission tomography is not available or in case of certain indolent lymphoma types, Tc-99m depreotide may have a role as an adjunct to conventional imaging procedures. [ABSTRACT FROM AUTHOR]

We present the case of a 17-year-old ice-hockey player, who complained about persistent left medial knee pain having undergone a refixation of a grade III osteochondritis dissecans with biodegradable pins, a reconstruction of the anterior cruciate ligament (ACL) and a medial meniscal repair 1 year previously. Sequential MRIs performed 8 and 12 months after surgery were inconclusive, and failed to show the insufficient integration of the osteochondral fragment. Combined single photon emission and conventional computerized tomography (SPECT/CT) clearly revealed the cause of the patient's persistent knee problems-the osteochondral fragment had not integrated. SPECT/CT may hold great clinical value for symptomatic patients who have previously undergone treatment for osteochondral lesions, and it should be considered as alternative diagnostic imaging modality. [ABSTRACT FROM AUTHOR]

Objective: Clinical evidence indicates that the Tourette’s syndrome (TS) is associated with hyperactivity of the dopaminergic system; however, imaging studies of dopamine transporter (DAT) in TS patients remain controversial. In this study, we aimed to study DAT binding capacities in a relatively larger sample of drug-naive patients with TS in comparison with controlled subjects by Tc-TRODAT-1 SPECT/CT imaging. We also aimed to look for any possible correlations between DAT and age, disease duration or tic severity of TS, which have not been thoroughly investigated in previous studies. We tried to provide more evidence for the understanding of the physiopathological mechanism of TS from the molecular imaging perspective. Methods: Eighteen drug-naive patients with TS and 8 age- and gender-matched healthy subjects were recruited. Severity of TS was measured with Yale Global Tic Severity Scale. Brain SPECT/CT was performed 2.5 h after injection of Tc-TRODAT-1. Regions of interest were drawn on the striatum including its sub-regions of caudate and putamen. The cerebellum was used as the reference region. DAT uptake ratio was calculated by subtracting the mean counts per pixel in the cerebellum from the mean counts per pixel in the striatum, caudate or putamen and by dividing the result by the mean counts per pixel in the cerebellum. Comparisons of DAT uptake ratios between TS patients and controls, and comparisons in bilateral striatum and sub-regions in TS patients were carried out. Correlation analysis between DAT uptake ratios and clinical data were also conducted. Results: TS patients showed significantly higher uptake of Tc-TRODAT-1 in bilateral striatum in comparison with the controls. There was no group-specific preferential lateralization in striatal uptake. DAT uptake ratios were not correlated with age and tic severity scores, but significant negative correlation with disease duration was found. Conclusions: High level of DAT was demonstrated in drug-naive TS patients compared with normal controls, and it was negatively correlated with TS duration. Therefore, with the extension of the disease duration, certain degree of adaptation might occur in TS patients to compensate for the DAT increase, which suggested that hyper-functional DAT might be involved in the early pathophysiological changes of TS. [ABSTRACT FROM AUTHOR]

Correlating the anatomical information from CT with the functional information from SPECT improves diagnostic accuracy of somatostatin-receptor-scintigraphy (SRS) in patients with neuroendocrine tumors (NET). The aim of the present study was to investigate the impact of dual modality SPECT/CT on the inter-rater agreement in SRS. Twenty-five unselected patients with suspected or histologically proven NET in whom whole body planar imaging and low-dose SPECT/CT had been performed after injection of 200 MBq In-111-octreotide were included retrospectively. Images were interpreted independently by 2 nuclear medicine physicians, an experienced one and an inexperienced one. Both readers first re-evaluated the planar whole-body images alone, then added the SPECT images, and finally the CT-images. Lesions with pathologically increased tracer uptake were categorized according to the following 3-point score: equivocal, probably pathologic, and definitely pathologic. Cohen’s linear-weighted kappa coefficient κ was used to quantify inter-rater agreement. A total number of 50 lesions were described in 23 of the 25 patients. The two readers showed only moderate agreement in the interpretation of the planar findings (κ = 0.593). Agreement improved to substantial by adding SPECT (κ = 0.736) and to very good by adding SPECT/CT (κ = 0.860). SPECT/CT resulted in up-staging of 18% of the lesions and down-staging of 12% compared to planar + SPECT (experienced reader). In addition, SPECT/CT tended to reduce the frequency of indefinite scores (equivocal, probably pathologic), from 18% in planar + SPECT to 6% ( p = 0.065). Change of lesion localization by SPECT/CT tended to contribute to the change of lesion score ( p = 0.055). The present results suggest that low-dose SPECT/CT stabilizes report quality in SRS by improving inter-rater agreement. [ABSTRACT FROM AUTHOR]

The field of noninvasive cardiac imaging has experienced enormous advances including computerized tomography coronary angiography (CTCA). Invasive angiography remains the anatomic standard of reference but it is associated with a non-negligible peri-procedural morbidity and mortality which suggests confining its use to patients who will benefit from a revascularization procedure. Many factors that are beyond the simple quantification of diameter narrowing and therefore cannot be fully assessed with luminology will eventually determine whether or not a given lesion produces stress-induced ischemia. Myocardial perfusion scintigraphy by single photon emission computerized tomography (SPECT) is one of the most widely used and well established noninvasive tools for the diagnosis of ischemic heart disease. Although positron emission tomography (PET) offers a higher accuracy than SPECT its use is often limited to large centers. This article explains the great potential of cardiac hybrid imaging which allows a comprehensive evaluation of coronary artery disease as it combines both morphological and functional information by fusing either SPECT or PET with CTCA. SPECT/CT and PET/CT hybrid imaging can provide entirely noninvasively unique information which helps improving diagnostic assessment and risk stratification and also impacts decision making with regard to revascularization in patients with coronary artery disease. [ABSTRACT FROM AUTHOR]