Annals of Nuclear Medicine (v.30, #4)

Simultaneous acquisition of 99mTc- and 123I-labeled radiotracers using a preclinical SPECT scanner with CZT detectors by Masato Kobayashi; Ichiro Matsunari; Kodai Nishi; Asuka Mizutani; Yoshiharu Miyazaki; Kazuhiro Ogai; Jyunko Sugama; Kazuhiro Shiba; Keiichi Kawai; Seigo Kinuya (263-271).
Simultaneous acquisition of 99mTc and 123I was evaluated using a preclinical SPECT scanner with cadmium zinc telluride (CZT)-based detectors.10-ml cylindrical syringes contained about 37 MBq 99mTc-tetrofosmin (99mTc-TF) or 37 MBq 123I-15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid (123I-BMIPP) were used to assess the relationship between these SPECT radioactive counts and radioactivity. Two 10-ml syringes contained 100 or 300 MBq 99mTc-TF and 100 MBq 123I-BMIPP to assess the influence of 99mTc upscatter and 123I downscatter, respectively. A rat-sized cylindrical phantom also contained both 100 or 300 MBq 99mTc-TF and 100 MBq 123I-BMIPP. The two 10-ml syringes and phantom were scanned using a pinhole collimator for rats. Myocardial infarction model rats were examined using 300 MBq 99mTc-TF and 100 MBq 123I-BMIPP. Two 1-ml syringes contained 105 MBq 99mTc-labeled hexamethylpropyleneamine oxime (99mTc-HMPAO) and 35 MBq 123I-labeled N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane (123I-FP-CIT). The two 1-ml syringes were scanned using a pinhole collimator for mice. Normal mice were examined using 105 MBq 99mTc-HMPAO and 35 MBq 123I-FP-CIT.The relationship between SPECT radioactive counts and radioactivity was excellent. Downscatter contamination of 123I-BMIPP exhibited fewer radioactive counts for 300 MBq 99mTc-TF without scatter correction (SC) in 125–150 keV. There was no upscatter contamination of 99mTc-TF in 150–175 keV. In the rat-sized phantom, the radioactive count ratio decreased to 4.0 % for 300 MBq 99mTc-TF without SC in 125–150 keV. In the rats, myocardial images and radioactive counts of 99mTc-TF with the dual tracer were identical to those of the 99mTc-TF single injection. Downscatter contamination of 123I-FP-CIT was 4.2 % without SC in 125–150 keV. In the first injection of 99mTc-HMPAO and second injection of 123I-FP-CIT, brain images and radioactive counts of 99mTc-HMPAO with the dual tracer in normal mice also were the similar to those of the 99mTc-HMPAO single injection. In the first injection of 123I-FP-CIT and second injection of 99mTc-HMPAO, the brain images and radioactive counts with the dual tracer were not much different from those of the 123I-FP-CIT single injection.Dual-tracer imaging of 99mTc- and 123I-labeled radiotracers is feasible in a preclinical SPECT scanner with CZT detector. When higher radioactivity of 99mTc-labeled radiotracers relative to 123I-labeled radiotracers is applied, correction methods are not necessarily required for the quantification of 99mTc- and 123I-labeled radiotracers when using a preclinical SPECT scanner with CZT detector.
Keywords: Dual tracer; 99mTc; 123I; Small animal SPECT scanner; Cadmium zinc telluride

Temporal epilepsy lesions may be detected by the voxel-based quantitative analysis of brain FDG-PET images using an original block-matching normalization software by Antoine Verger; Yalcin Yagdigul; Axel Van Der Gucht; Sylvain Poussier; Eric Guedj; Louis Maillard; Grégoire Malandain; Gabriela Hossu; Renaud Fay; Gilles Karcher; Pierre-Yves Marie (272-278).
Statistical parametric mapping (SPM) provides useful voxel-by-voxel analyses of brain images from 18F-fluorodesoxyglucose positron emission tomography (FDG-PET) after an initial step of spatial normalization through an anatomical template model. In the setting of the preoperative workup of patients with temporal epilepsy, this study aimed at assessing a block-matching (BM) normalization method, where most transformations are computed through small blocks, a principle that minimizes artefacts and overcomes additional image-filtering. Brain FDG-PET images from 31 patients with well-characterised temporal lobe epilepsy and among whom 22 had common mesial temporal lobe epilepsy were retrospectively analysed using both BM and conventional SPM normalization methods and with PET images from age-adjusted controls. Different threshold p values corrected for cluster volume were considered (0.01, 0.005, and 0.001).The use of BM provided equivalent values to those of SPM with regard to the overall volumes of temporal and extra-temporal hypometabolism, as well as similar sensitivity for detecting the involved temporal lobe, reaching 87 and 94 % for SPM and BM, respectively, at a threshold p value of 0.01. However, the ability to more accurately localize brain lesions within the mesial portion of the temporal lobe was a little higher with BM than with SPM with respective sensitivities reaching 78 % for BM and 45 % for SPM (p < 0.05).BM normalization compares well with conventional SPM for the voxel-based quantitative analysis of the FDG-PET images from temporal epilepsy patients. Further studies in different population are needed to determine whether BM is truly an accurate alternative to SPM in this setting.
Keywords: FDG-PET; Mesial temporal lobe epilepsy; Spatial normalization; Statistical parametric mapping; Block-matching algorithm

Prognostic value of 18F-fluorodeoxyglucose positron emission tomography in patients with gastric neuroendocrine carcinoma and mixed adenoneuroendocrine carcinoma by Sun Min Lim; Hyunki Kim; Beodeul Kang; Hyo Song Kim; Sun Young Rha; Sung Hoon Noh; Woo Jin Hyung; Jae-Ho Cheong; Hyoung-Il Kim; Hyun Cheol Chung; Mijin Yun; Arthur Cho; Minkyu Jung (279-286).
Gastric neuroendocrine carcinomas (NEC) and mixed adenoneuroendocrine carcinoma (MANEC) are very rare, aggressive tumors of the stomach. We aimed to examine predictive role of pretreatment 18F-FDG PET/CT-assessed metabolic parameter of primary tumors and metastases in patients with gastric NEC and MANEC.We conducted a review of the 27 patients with histopathologically confirmed NECs (n = 10) and MANEC (n = 17) of the stomach at our institution between January 2005 and December 2012. All patients underwent 18F-FDG-PET examination at diagnosis. Metabolic parameters [SUVmax, SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG)] of the primary tumor and metastases on baseline PET/CT were analyzed.The median follow-up duration was 39.4 months (95 % CI 20.0–58.1 months) and the median overall survival (OS) was 25.7 months (95 % CI 14.1–37.2 months). All gastric lesions were well visualized (average SUVmax = 12.0, range 3.0–41.8). When subjects were divided into two groups by ROC cut-off value of 210.9 and 612, patients with high TLG in primary lesion and metastases showed poorer prognosis compared to low TLG patients (P = 0.09, P = 0.002, respectively). In the sub-analysis of patients with metastasis (n = 12), patients with high TLG in whole body tumor showed significantly shorter OS compared to those with low TLG (31.7 ± 11.4 vs. 7.2 ± 2.1 months, P = 0.006). 18F-FDG PET/CT is useful in evaluating prognosis of advanced gastric cancer with neuroendocrine carcinoma components. Baseline MTV of primary gastric cancer with metastatic disease, and MTV, TLG of metastases may be prognostic markers in patients with gastric NEC and MANEC.
Keywords: 18F-FDG PET/CT; Survival; Gastric; Neuroendocrine carcinoma; Mixed adenoneuroendocine carcinoma

F-18-FDG-avid lymph node (LN) metastasis may preferentially occur along the lymphatic drainage pathway (LDP) from the tumor-bearing lobe in patients with non-small cell lung cancer (NSCLC) on FDG PET/CT. This study evaluated whether the identification of metastatic LNs according to LDP-based visual image interpretation can improve LN staging on FDG PET/CT in these patients.FDG PET/CT study was performed in 265 patients with NSCLC. The presence and LN station of metastatic LNs were determined by surgery or the clinical course. In the LDP-based interpretation, FDG-avid LNs, which were located along the preferential LDP from each tumor-bearing lobe and visually more intense in FDG uptake compared with the remaining LNs straying away from the preferential LDP, were diagnosed as metastatic. The result was compared with the quantitative method using a cutoff value of 2.5 for the maximum standardized uptake value.Of the total 1031 mediastinal and hilar LN stations with FDG-avid LNs in 265 patients, 179 stations in 66 patients were metastatic and the remaining 852 were benign. All the metastatic LN stations except for 2 stations showing skip metastasis were located along the main preferential LDP or another preferential LDP via a direct anatomic pathway from each tumor-bearing lung lobe. The specificity, accuracy, and PPV for identifying metastatic LN stations by LDP-based interpretation were 97.9, 95.7 and 89.5 %, respectively, which were significantly greater compared with those of 92.7, 90.8 and 70.3 % by the SUV-based method (P < 0.001).The present study shows that FDG-avid LN metastasis preferentially occurs along the LDP from the tumor-bearing lobe in NSCLC patients. LDP-based visual image interpretation on FDG PET/CT can improve LN staging in these patients.
Keywords: F-18-FDG-PET/CT; Non-small-cell lung cancer (NSCLC); Lymph node; Metastasis; Lymphatic drainage pathways

This study aimed to evaluate the usefulness of the subtraction method for improving sentinel lymph node (SLN) visibility by reducing scattering near the injection site.Images of two phantoms for the injection site and SLNs built using an original design were simultaneously acquired using a dual-head camera equipped with a low-energy high-resolution collimator on the lower detector (posterior view) and a low-energy general-purpose collimator on the upper detector (anterior view). Subtraction method images were created by subtracting the posterior view from the anterior view, the latter of which was designated as the conventional method. Image contrast was calculated from the counts of regions of interest placed on the two phantoms of the injection site and SLNs. SLNs visibility to a distance from the injection site and a radioactivity ratio based on the injection site (15 MBq) was evaluated by image contrast and visual interpretation.The best improvement in contrast occurred at a distance of 20 pixels (1.08 mm/pixel) from the injection site, and improved further as the lymph node radioactivity was smaller. The SLN’s visibility corresponding to a distance of 20 pixels improved significantly (p < 0.001), from 1/2560 of radioactivity at the injection site (approximately 6 kBq) to 1/640 (approximately 23 kBq), and the SLN was only detectable using the subtraction method. The SLN (1/5120, approximately 3 kBq) was difficult to detect even with the subtraction method, whereas the SLN with a ratio ≥1/320 (approximately 46 kBq) was easily detected even with the conventional method. These visibilities did not differ significantly between the two methods (p = 0.16 and >0.32, respectively). The subtraction method could detect SLNs near the tumor on clinical images.The subtraction method improved SLN visibility near the injection site by reducing scattering from the injection site. Furthermore, an advantage of the subtraction method is that it does not require additional imaging, because the posterior view is obtained simultaneously and utilized.
Keywords: Sentinel lymph node; Lymphoscintigraphy; Breast cancer

Differentiating the grades of thymic epithelial tumor malignancy using textural features of intratumoral heterogeneity via 18F-FDG PET/CT by Hyo Sang Lee; Jungsu S. Oh; Young Soo Park; Se Jin Jang; Ik Soo Choi; Jin-Sook Ryu (309-319).
We aimed to explore the ability of textural heterogeneity indices determined by 18F-FDG PET/CT for grading the malignancy of thymic epithelial tumors (TETs).We retrospectively enrolled 47 patients with pathologically proven TETs who underwent pre-treatment 18F-FDG PET/CT. TETs were classified by pathological results into three subgroups with increasing grades of malignancy: low-risk thymoma (LRT; WHO classification A, AB and B1), high-risk thymoma (B2 and B3), and thymic carcinoma (TC). Using 18F-FDG PET/CT, we obtained conventional imaging indices including SUVmax and 20 intratumoral heterogeneity indices: i.e., four local-scale indices derived from the neighborhood gray-tone difference matrix (NGTDM), eight regional-scale indices from the gray-level run-length matrix (GLRLM), and eight regional-scale indices from the gray-level size zone matrix (GLSZM). Area under the receiver operating characteristic curve (AUC) was used to demonstrate the abilities of the imaging indices for differentiating subgroups. Multivariable logistic regression analysis was performed to show the independent significance of the textural indices. Combined criteria using optimal cutoff values of the SUVmax and a best-performing heterogeneity index were applied to investigate whether they improved differentiation between the subgroups.Most of the GLRLM and GLSZM indices and the SUVmax showed good or fair discrimination (AUC >0.7) with best performance for some of the GLRLM indices and the SUVmax, whereas the NGTDM indices showed relatively inferior performance. The discriminative ability of some of the GLSZM indices was independent from that of SUVmax in multivariate analysis. Combined use of the SUVmax and a GLSZM index improved positive predictive values for LRT and TC.Texture analysis of 18F-FDG PET/CT scans has the potential to differentiate between TET tumor grades; regional-scale indices from GLRLM and GLSZM perform better than local-scale indices from the NGTDM. The SUVmax and heterogeneity indices may have complementary value in differentiating TET subgroups.
Keywords: Thymic epithelial tumor; Thymoma; 18F-FDG PET/CT; Intratumoral heterogeneity; Texture analysis

Decreased dopamine transporter and receptor ligand binding in Parkinsonism with diabetic uremic syndrome by Kazuhiro Ishii; Kenji Ishii; Ayako Shioya; Kiyotaka Nemoto; Akira Tamaoka (320-324).
Here, we describe the case of a 47-year-old man with bilateral striatal lesions with diabetic uremia. Following 4 years of hemodialysis, the patient experienced sudden onset of rigidity, bradykinesia, gait disorder, and postural instability. Symptoms were remediated 2 months later, and were no longer responsive to levodopa approximately 1 year after the onset. Brain magnetic resonance imaging (MRI) during the acute phase showed T 2-weighted high signal edematous lesions in the bilateral striatum, subsequently developing into vacuolated lesions. A positron emission tomography (PET) scan using (11C)-labeled 2-carbomethoxy-3-(4-fluorophenyl) tropane [(11C) CFT] and (11C)-labeled raclopride [(11C) RAC] revealed significant decreases bilaterally in pre- and postsynaptic functions of the dopaminergic neurons. When we experience a case with bilateral putaminal destruction resulting in Parkinsonism, examination of the function of doperminergic neurons and dopamine receptors using molecular imaging is useful to predict levodopa response and prognosis.
Keywords: Osmotic demyelination syndrome; Diabetic uremic syndrome; Positron emission tomography; Striatum