Sellam Karunanithi

Role of (68)Ga-DOTATOC PET-CT in the diagnosis and staging of pancreatic neuroendocrine tumours.

ObjectiveThe objective of the present study was to evaluate the role of 68Ga-DOTA(0)-Phe(1)-Tyr(3)-octreotide (68Ga-DOTATOC) positron emission tomography computed tomography (PET-CT) for detection and staging of pancreatic neuroendocrine tumours (NETs).MethodsTwenty patients with clinically suspected and/or histopathologically proven pancreatic NET underwent 68Ga-DOTATOC PET-CT imaging for staging and /or localisation of primary lesion. They also underwent contrast enhanced CT (CECT) and 8 patients underwent 18F-FDG PET-CT. SUVmax of primary and metastatic lesions were measured. Results were verified with histopathology for primary tumour and with clinical follow up/MRI and /or biopsy for metastatic disease. Results of 68Ga-DOTATOC PET-CT were compared to CECT and 18F-FDG PET-CT.Results68Ga-DOTATOC PET-CT correctly localised primary in all 20, CECT in 15 and 18F-FDG PET-CT in 2 patients. 68Ga-DOTATOC PET-CT demonstrated metastases in 13 patients, CECT in 7 and 18F-FDG PET-CT in 2. 68Ga-DOTATOC PET-CT emerged as the best investigation with 100% sensitivity and PPV for detecting primary tumour and metastatic disease. The detection rate of CECT was lower than 68Ga-DOTATOC PET-CT, both for primary tumour (20vs.15) or metastatic disease (13vs.7). 18F-FDG PET-CT performed poorly for primary and metastasis.ConclusionGa-DOTATOC PET-CT is a very useful imaging investigation for diagnosing and staging pancreatic NET.

68Ga-DOTANOC PET/CT for Baseline Evaluation of Patients with Head and Neck Paraganglioma

The purpose of this study was to evaluate the role of 68Ga-labeled DOTANOC PET/CT for baseline evaluation of patients with head and neck paragangliomas (HNPs). Methods: The data for 26 patients (mean age ± SD, 34.3 ± 10.4 y; 50% men) with known or suspected HNPs who underwent 68Ga-DOTANOC PET/CT for staging were retrospectively analyzed. PET/CT was performed after intravenous injection of 132–222 MBq of 68Ga-DOTANOC. The images were evaluated by 2 experienced nuclear medicine physicians in consensus, both qualitatively and quantitatively. The PET/CT findings were grouped as HNPs, paraganglioma at other sites (non-HNPs), and metastatic disease. The size and maximum standardized uptake values (SUVmax) were measured for all lesions. All of the patients also underwent whole-body 131I-metaiodobenzylgunanidine (131I-MIBG) scintigraphy and conventional imaging (CT/MR imaging) of the head and neck region. Their results were compared with those of 68Ga-DOTANOC PET/CT. Results: 68Ga-DOTANOC PET/CT findings were positive in all 26 patients, and 78 lesions were detected. PET/CT imaging demonstrated 45 HNPS, 10 non-HNPs, and 23 metastatic sites. Fifteen patients (57.6%) had more than one site of disease on PET/CT. Among 45 HNPs, 26 were carotid body tumors (CBTs), 15 glomus jugulare, 3 glomus tympanicum, and 1 laryngeal paraganglioma. A positive correlation was seen between size and SUVmax of HNPs (ρ = 0.323; P = 0.030). The SUVmax of the CBTs was higher than that of jugulotympanic paragangliomas (P = 0.026). No correlation was seen between size and SUVmax (ρ = 0.069; P = 0.854) of non-HNPs. The size and SUVmax of non-HNPs were significantly less than those of HNPs (P = 0.029 and 0.047, respectively). 131I-MIBG scintigraphy showed only 30 of the 78 lesions and was inferior to PET/CT (P < 0.0001). Conventional imaging (CT/MR imaging) was positive for 42 of 49 head and neck lesions and was inferior to PET/CT on direct comparison (P = 0.015). A combination of CT/MR imaging and 131I-MIBG scintigraphy detected only 53 of 78 (67.9%) lesions and was also inferior to PET/CT (P < 0.0001). Conclusion: 68Ga-DOTANOC PET/CT is useful for the baseline evaluation of patients with HNPs and can demonstrate synchronous paragangliomas at other sites and distant metastases. It is superior to 131I-MIBG scintigraphy and conventional imaging (CT/MR imaging) for this purpose.

18F-FDG PET-CT in the diagnosis of tumor thrombus: can it be differentiated from benign thrombus?

ObjectiveThe correct diagnosis of tumor thrombosis and its differentiation from benign thrombus can change patient management and prevent unnecessary anticoagulation treatment. This study was aimed at evaluating the role of fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) in the diagnosis of tumor thrombosis, and its differentiation from benign thromboembolism. MethodsWe conducted a retrospective review of FDG PET-CT scans of patients who underwent the study for staging/restaging of a known malignancy and had FDG-avid thrombosis. Maximum standardized uptake value (SUVmax) of the thrombus, SUVmax of tumor (if any), and SUVmax of mediastinal blood pool were calculated. PET-CT results were confirmed with clinical follow-up, structural imaging, and histopathology when available. ResultsA total of 24 patients (15 male and nine female) with a mean age of 43.8 years (range: 3–72 years; median: 47.5 years) were evaluated. On the basis of structural imaging and clinical follow-up, 10 patients had benign and 14 patients had tumor thrombosis. On FDG PET-CT, uptake in the thrombus was linear in 18 patients and focal in six patients. The most common site of thrombosis was the inferior vena cava. The mean SUVmax was 3.2 (range: 2.3–4.6; median: 3.3) in the benign thrombosis group and was 6.0 (range: 2.3–13.8; median: 3.3) in the tumor thrombosis group. The difference in SUVmax was significant (P=0.013). On receiver operating characteristic analysis, a cut-off SUVmax of 3.63 (sensitivity: 71.4% and specificity: 90%) was obtained to differentiate tumor thrombus from benign thromboembolism. In six patients, FDG PET-CT detected occult vascular thrombosis. ConclusionFDG PET-CT can detect active tumor thrombosis and is helpful in differentiating it from benign thrombus.

Dual tracer functional imaging of gastroenteropancreatic neuroendocrine tumors using 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT: competitive or complimentary?

Objective This study aimed to compare the diagnostic performance of 68Ga-DOTANOC PET/CT with 18F-FDG PET/CT in the patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Patients and Methods Data of 51 patients with definite histological diagnosis of GEP-NET who underwent both 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT within a span of 15 days were selected for this retrospective analysis. Sensitivity, specificity, and predictive values were calculated for 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT, and results were compared both on patientwise and regionwise analysis. Results 68Ga-DOTA-NOC PET-CT is superior to 18F-FDG PET-CT on patientwise analysis (P < 0.0001). On regionwise analysis, 68Ga-DOTA-NOC PET-CT is superior to 18F-FDG PET-CT only for lymph node metastases (P < 0.003). Although 68Ga-DOTA-NOC PET-CT detected more liver and skeletal lesions compared with 18F-FDG PET-CT, the difference was not statistically significant. In addition, the results of combined imaging helped in selecting candidates who would undergo the appropriate mode of treatment, whether octreotide therapy or conventional chemotherapy Conclusions 68Ga-DOTA-NOC PET-CT seems to be superior to 18F-FDG PET-CT for imaging GEP-NETs. However, their role seems to be complementary because combination of 68Ga-DOTA-NOC PET-CT and 18F-FDG PET-CT in such patients helps demonstrate the total disease burden and segregate them to proper therapeutic groups.

Potential Role of 18F-FDG PET/CT in Patients With Fungal Infections

OBJECTIVE Combined anatomic and functional imaging with (18)F-FDG PET/CT is slowly gaining foothold in the management of various infective pathologic abnormalities. However, limited literature is available regarding the role of FDG PET/CT in patients with fungal infections. CONCLUSION Here, we briefly review the available literature and highlight the potential role that FDG PET/CT can play in the diagnosis and management of fungal infections.

Comparative Accuracy of Ct Attenuation-corrected and Non–attenuation-corrected Spect Myocardial Perfusion Imaging

Objective: The aim of the present study was to evaluate whether computed tomography based-attenuation correction (CT-AC) provides any advantage over non–attenuation-corrected (NAC) images for qualitative and quantitative analysis of single photon emission tomography (SPECT) myocardial perfusion imaging (MPI). Methods: We retrospectively evaluated data of 171 patients who underwent stress rest MPI SPECT/CT as per standard protocol. Angiography done within ±3 months of MPI was taken as reference standard. Two readers independently evaluated CT-AC and NAC images. Receiver operating characteristic curve analysis was done using ≥50% and ≥70% stenosis as cutoff. The size and severity of perfusion defects were also compared on CT-AC and NAC images. Results: For both readers, the area under the receiver operating characteristic curve was larger for CT-AC images than for NAC images at both ≥50% and ≥70% cutoff, but the difference was not significant. CT-AC images had significantly lower sensitivity for detecting right coronary artery disease compared with NAC (29% vs. 50% for reader 1 and 25.8% vs. 43.2% for reader 2). However, the specificity improved with CT-AC. Inferior defects were significantly smaller in CT-AC than NAC (P = 0.0002), with no significant difference for anterior defects (P = 0.544). There was significant variation in severity between CT-AC and NAC images for both overall (P = 0.001) as well as for inferior defects (P = 0.0007), but not for anterior defects (P = 0.279). Conclusion: In our study, the CT-based AC improved the specificity but decreased the sensitivity leading to nonsignificant improvement in overall diagnostic accuracy of Tc-99m sestamibi/tetrofosmin MPI.

99mTc-Methylene diphosphonate SPECT/CT as the one-stop imaging modality for the diagnosis of osteoid osteoma.

PurposeThe aim of this study was to evaluate the utility of 99mTc-methylene diphosphonate (99mTc-MDP) single-photon emission tomography (SPECT)/computed tomography (CT) for the diagnosis of osteoid osteoma and compare the same with three-phase planar bone scintigraphy (BS) and CT alone. Materials and methodsData of 31 patients (age: 20.6±13.2 years; male: 80.6%) who had undergone 99mTc-MDP BS with SPECT/CT for clinically and/or radiographically suspected osteoid osteoma were retrospectively evaluated. Planar BS images were analyzed by an experienced nuclear medicine physician. CT images were evaluated by an experienced radiologist. SPECT/CT images were evaluated by the nuclear medicine physician and radiologist in consensus. On the basis of the diagnostic confidence the interpreters used a scoring scale of 1–3, in which 1 is negative for osteoid osteoma, 2 is equivocal, and 3 is positive for osteoid osteoma. For the calculation of sensitivity, specificity, and predictive values for planar BS, CT, and SPECT/CT an interpretive score of 2 or higher was taken as positive for osteoid osteoma. Receiver operating characteristic curve analysis was performed and the area under the curve was calculated and compared. Histopathology and microbiology/clinical imaging follow-up was used as the reference standard. ResultsThere were nine equivocal lesions on planar BS and five equivocal lesions on CT, but none on SPECT/CT. The sensitivity, specificity, and accuracy of SPECT/CT were all 100%; those of CT were 77.8, 92.3, and 83.8% and those of planar BS were 100, 38.4, and 74.1%, respectively. On comparison, the area under the curve of SPECT/CT was significantly larger than that of planar BS (1.00 vs. 0.761; P=0.005) and CT (1.00 vs. 0.872; P=0.044). However, no significant difference was seen between planar BS and CT (0.761 vs. 0.872; P=0.236). Conclusion99mTc-MDP SPECT/CT shows excellent diagnostic accuracy for osteoid osteoma and can be used as a one-stop imaging modality for the same. It is superior to planar BS and CT alone for the diagnosis of suspected osteoid osteoma.

Accuracy of 68Ga DOTANOC PET/CT Imaging in Patients With Multiple Endocrine Neoplasia Syndromes.

Objective The aim of this study was to evaluate the role of 68Ga DOTANOC PET/CT imaging in patients with multiple endocrine neoplasia (MEN) syndromes. Patients and Methods Data of 33 patients (age, 33.5 [13.8] years; male 14/female 19) with MEN syndromes (MEN 1, 9; MEN 2A, 19; MEN 2B, 5) who underwent 41 68Ga DOTANOC PET/CT studies were retrospectively analyzed. Twenty PET/CTs were done for staging and 21 for restating. PET/CT images were evaluated in consensus by 2 nuclear medicine physicians, qualitatively and semiquantitatively (SUVmax). A combination of histopathology, clinical, and biomarker follow-up was taken as reference standard. Results Of the total 41 68Ga DOTANOC PET/CTs, 34 were interpreted as positive for neuroendocrine tumors (NETs) and 7 as negative. The patientwise sensitivity of PET/CT was 94% (95% confidence interval [CI], 80–99), specificity was 71% (95% CI, 29–96), positive predictive value was 94% (95% CI, 80–99), negative predictive value was 71% (95% CI, 29–96), and accuracy was 90%. A total of 74 disease sites were demonstrated on PET/CT, including 41 primary NETs (pancreas, 10; stomach, 2; pheochromocytoma, 10; medullary thyroid carcinoma, 19), 31 metastatic sites (lymph node, 15; liver, 10; bone, 4; lung, 1; breast, 1), and 2 parathyroid adenomas. Lesionwise sensitivity, positive predictive value, and accuracy of PET/CT were 93%, 96%, and 90% overall, 89%, 95%, and 85% for primary tumors, and 100%, 97%, and 97% for metastasis, respectively. Among primary tumors, the SUVmax of medullary thyroid carcinoma was significantly lower than gastro pancreatic NETs (P = 0.003) and pheochromocytomas (P = 0.003). No site-specific difference was seen in SUVmax of metastatic lesions. Conclusions 68Ga DOTANOC PET/CT shows high diagnostic accuracy in MEN syndrome and can demonstrate both primary and metastatic NETs in these patients.

68Ga-DOTATOC PET-CT in the localization of source of ectopic ACTH in patients with ectopic ACTH-dependent Cushing's syndrome

Localization of the source of adrenocorticotrophic hormone (ACTH) in ectopic ACTH-induced Cushings syndrome is of paramount importance as definitive management mainly involves surgical resection of tumor. Many of these are occult, not identified by conventional structural imaging. Accurate localization and assessment of their functional status has become feasible with the use positron emission tomography-computerized tomography using (68)Ga-DOTATOC (1,4,7,10-tetraazacy-clododecane-NI,NII,NIII,NIIII-tetraacetic acid(D)-Phe1-thy3-octreotide), aiding in proper planning for their definitive management.

Prospective Comparison of 99mTc-GH SPECT/CT and 18F-FDOPA PET/CT for Detection of Recurrent Glioma: A Pilot Study

Objective This study aimed to evaluate and compare the role of 99mTc-GH SPECT/CT and 18F-FDOPA PET/CT for diagnosing recurrence in patients with glioma. Methods Thirty patients with histopathologically proven glioma (glioblastoma multiforme, 14; grade III, 6; grade II, 8; and grade I, 2), who presented with clinical and/or imaging suspicion of recurrence were prospectively evaluated. They were primarily treated with surgery and radiotherapy with or without chemotherapy. Each patient underwent 99mTc-GH SPECT/CT and 18F-FDOPA PET/CT within a span of 15 days. Images were evaluated qualitatively and quantitatively by 2 experienced nuclear medicine physicians in consensus. Histopathology and/or clinical/imaging follow-up were used as reference standard. Results Based on reference standard, 22 patients were positive and 8 were negative for recurrence. 99mTc-GH SPECT/CT was positive for recurrence in 22 and negative in 8 patients. 18F-FDOPA PET/CT scan was positive for recurrence in 23 and negative in 7 patients. Sensitivity, specificity, and accuracy were 86.4%, 62.5%, and 80% for 99mTc-GH SPECT/CT and 100%, 87.5%, and 96% for 18F-FDOPA PET/CT, respectively. No significant difference was found between 99mTc-GH SPECT/CT and 18F-FDOPA PET/CT overall (P = 1.00), as well as for low-grade (P = 0.250) or high-grade tumors (P = 0.50). Significant correlation was noted between tumor-brain of 99mTc-GH with both tumor-striatum (r = 0.371; P = 0.044) and tumor-cerebellum ratio of 18F-FDOPA (r = 0.369; P = 0.045). Conclusions For detection of recurrence in glioma patients, 99mTc-GH SPECT/CT is not inferior to 18F-FDOPA PET/CT and can be used as a low-cost alternative.