Comparison of single photon emission computed tomography-computed tomography, computed tomography, single photon emission computed tomography and planar scintigraphy for characterization of isolated skull lesions seen on bone scintigraphy in cancer patients.

PURPOSE: The purpose of this study is to evaluate the added value of single photon emission computed tomography-computed tomography (SPECT-CT) over planar scintigraphy, SPECT and CT alone for characterization of isolated skull lesions in bone scintigraphy (BS) in cancer patients. MATERIALS AND METHODS: A total of 32 cancer patients (age: 39.5 ± 21.9; male: female - 1:1) with 36 isolated skull lesions on planar BS, underwent SPECT-CT of skull. Planar BS, SPECT, CT and SPECT-CT images were evaluated in separate sessions to minimize recall bias. A scoring scale of 1-5 was used, where 1 is definitely metastatic, 2 is probably metastatic, 3 is indeterminate, 4 is probably benign and 5 is definitely benign. With receiver operating characteristic analysis area under the curves (AUC) was calculated for each modality. For calculation of sensitivity, specificity and predictive values a Score ≤3 was taken as metastatic. Clinical/imaging follow-up and/or histopathology were taken as reference standard. RESULTS: Of 36 skull lesions 11 lesions each were on frontal, parietal and occipital bone while three lesions were in the temporal bone. Of these 36 lesions, 16 were indeterminate (Score-3) on planar and SPECT, five on CT and none on SPECT-CT. The AUC was largest for SPECT-CT followed by CT, SPECT and planar scintigraphy, respectively. Planar scintigraphy was inferior to SPECT-CT (P = 0.006) and CT (P = 0.012) but not SPECT (P = 0.975). SPECT was also inferior to SPECT-CT (P = 0.007) and CT (P = 0.015). Although no significant difference was found between SPECT-CT and CT (P = 0.469), the former was more specific (100% vs. 94%). CONCLUSION: SPECT-CT is better than planar scintigraphy and SPECT alone for correctly characterizing isolated skull lesions on BS in cancer patients. It is more specific than CT, but provides no significant advantage over CT alone for this purpose.

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 Ga-DOTANOC PET/CT with F-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 Ga-DOTA-NOC PET-CT and F-FDG PET-CT within a span of 15 days were selected for this retrospective analysis. Sensitivity, specificity, and predictive values were calculated for Ga-DOTA-NOC PET-CT and F-FDG PET-CT, and results were compared both on patientwise and regionwise analysis. RESULTS: Ga-DOTA-NOC PET-CT is superior to F-FDG PET-CT on patientwise analysis (P < 0.0001). On regionwise analysis, Ga-DOTA-NOC PET-CT is superior to F-FDG PET-CT only for lymph node metastases (P < 0.003). Although Ga-DOTA-NOC PET-CT detected more liver and skeletal lesions compared with F-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: Ga-DOTA-NOC PET-CT seems to be superior to F-FDG PET-CT for imaging GEP-NETs. However, their role seems to be complementary because combination of Ga-DOTA-NOC PET-CT and F-FDG PET-CT in such patients helps demonstrate the total disease burden and segregate them to proper therapeutic groups.

68Ga-DOTANOC PET/CT for baseline evaluation of patients with head and neck paraganglioma.

UNLABELLED: The purpose of this study was to evaluate the role of (68)Ga-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 (68)Ga-DOTANOC PET/CT for staging were retrospectively analyzed. PET/CT was performed after intravenous injection of 132-222 MBq of (68)Ga-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 (131)I-metaiodobenzylgunanidine ((131)I-MIBG) scintigraphy and conventional imaging (CT/MR imaging) of the head and neck region. Their results were compared with those of (68)Ga-DOTANOC PET/CT. RESULTS: (68)Ga-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). (131)I-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 (131)I-MIBG scintigraphy detected only 53 of 78 (67.9%) lesions and was also inferior to PET/CT (P < 0.0001). CONCLUSION: (68)Ga-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 (131)I-MIBG scintigraphy and conventional imaging (CT/MR imaging) for this purpose.

Can hybrid SPECT-CT overcome the limitations associated with poor imaging properties of 131I-MIBG?: Comparison with planar scintigraphy and SPECT in pheochromocytoma.

OBJECTIVE: This study aimed to evaluate the incremental value of (131)I-MIBG hybrid SPECT-CT over planar scintigraphy (PS) and SPECT alone in patients with clinical or biochemical suspicion of pheochromocytoma. METHODS: A total of 126 adrenals of 63 patients (mean [SD] age, 28.6 [15.7] years; male patients, n = 34; female patients, n = 29) with clinical or biochemical suspicion of pheochromocytoma were retrospectively evaluated. All patients had undergone (131)I-MIBG SPECT-CT of adrenal region. The PS, SPECT, and SPECT-CT images were independently evaluated by 2 nuclear medicine physicians with 6 years (R1) and 2 years (R2) experience and in separate sessions 1 week apart. A scoring scale of 1 to 5 was used, in which 1 is definitely abnormal, 2 is probably abnormal, 3 is indeterminate, 4 is probably normal, and 5 is definitely normal. Sensitivity, specificity, predictive values were calculated taking a score 2 or less as abnormal. With receiver operating characteristic (ROC) curve analysis, areas under the curve (AUC) were calculated for each modality and compared. Histopathology and/or clinical/imaging follow-up were taken as reference standard. RESULTS: Of the 126 adrenals evaluated, 29 were indeterminate on PS for R1 and 48 for R2, 39 were indeterminate on SPECT for both, and on SPECT-CT, 1 was indeterminate for R1 and 2 for R2. SPECT-CT correctly characterized 28 of 29 indeterminate adrenals on PS and 37 of 39 indeterminate adrenals on SPECT for R1. Similarly, for R2, SPECT-CT correctly characterized 45 of 48 indeterminate adrenals on PS and 33 of 39 indeterminate adrenals on SPECT. On ROC comparison, PS was inferior to SPECT (P = 0.040 for R1; P < 0.001 for R2) and SPECT-CT (P = 0.001 for R1; P < 0.001 for R2) for both the observers. Moreover, SPECT was inferior to SPECT-CT for both the observers (P = 0.017 for R1 and P = 0.001 for R2). Accuracy of SPECT-CT (R1, 97.6%; R2, 97.6%) was higher than PS (R1, 91.2%; R2, 84.1%) and SPECT (R1, 94.4%; R2, 86.5%). Interobserver agreement was highest for SPECT-CT (κ = 0.966) as compared with PS (κ = 0.815) and SPECT (κ = 0.826). CONCLUSIONS: I-MIBG hybrid SPECT-CT shows high sensitivity and specificity for characterizing adrenal lesions in patients with clinical or biochemical suspicion of pheochromocytoma and is superior to PS and SPECT alone. It will be especially useful in countries where (123)I-MIBG is not available.

Sister Mary Joseph nodule in endometrial carcinoma: detection with FDG PET/CT.

Sister Mary Joseph nodules are very rare. They are commonly caused by gastrointestinal tract and ovarian cancers, but they are seen rarely in uterine carcinoma, lung carcinoma, breast carcinoma, and others. We present F-FDG PET/CT findings in a 55-year-old woman with endometrial adenocarcinoma, who presented with a mass protruding from the umbilicus after surgery and pelvic radiotherapy.

Hybrid SPECT-CT for characterizing isolated vertebral lesions observed by bone scintigraphy: comparison with planar scintigraphy, SPECT, and CT.

PURPOSE: We aimed to assess the role of single photon emission computed tomography-computed tomography (SPECT-CT) for characterizing isolated vertebral lesions observed by bone scintigraphy compared to planar scintigraphy, SPECT, and CT, and to evaluate the impact of SPECT-CT on patient management. MATERIALS AND METHODS: Data from 99 patients (mean age, 52.4±18.9 years; females, 58.5%) with 108 isolated vertebral lesions visible on planar bone scintigraphy, who had undergone SPECT-CT of a selected volume, were retrospectively analyzed. Planar scintigraphy, SPECT, CT, and SPECT-CT images were independently evaluated in separate sessions to minimize recall bias. A scoring scale of 1 to 5 was used, with 1 being definitely metastatic, 2 most likely metastatic, 3 indeterminate, 4 most likely benign, and 5 definitely benign. Sensitivity, specificity, and predictive values were calculated; a score ≤3 was defined as metastatic. The areas under the receiver operating characteristic curve were calculated and compared. Clinical and imaging followup with or without histopathology were used as a reference standard. RESULTS: Among the 108 lesions, 49 were indeterminate on planar scintigraphy, 16 on SPECT, and one each on SPECT-CT and CT. SPECT-CT was superior to both planar scintigraphy (P < 0.001) and SPECT alone (P = 0.014), but not to CT (P = 0.302). CT was superior to planar scintigraphy (P < 0.001) but only slightly superior to SPECT (P = 0.063). SPECT-CT correctly characterized 96% of the indeterminate lesions observed by planar scintigraphy. SPECT-CT had an impact on the clinical management of 60.6% patients compared to planar scintigraphy and 18.1% compared to SPECT. CONCLUSION: SPECT-CT is better than planar scintigraphy and SPECT alone, but not CT alone, for characterizing equivocal vertebral lesions that are observed by bone scintigraphy, thus SPECT-CT can have a significant impact on patient management.

68Ga-DOTA-NOC PET and peptide receptor radionuclide therapy in management of bilateral ovarian metastases from gastrointestinal carcinoid.

The management of neuroendocrine tumours is challenging when curative surgery is ruled out because of distant metastases. We report a case of gastrointestinal carcinoid with bilateral ovarian metastases in a 50-year-old female who received octreotide therapy followed by peptide receptor radionuclide therapy and surgery thereafter. Somatostatin receptor expression on neuroendocrine tumours has implications in diagnosis and therapy. (68)Ga-DOTA-NOC PET is a recent advancement in the field of somatostatin receptor imaging. The lesions which demonstrate tracer uptake on positron emission tomographic studies can be further planned for treatment with octreotide and (177)Lu-DOTA-TATE. The case in discussion responded well to non-invasive treatment options before proceeding to definitive surgical management.

18F-FDG PET-CT for detecting recurrent gastric adenocarcinoma: results from a Non-Oriental Asian population.

OBJECTIVE: To evaluate the utility of fluorine-18 fluorodeoxyglucose (18F-FDG) PET-CT in the diagnosis of recurrent gastric adenocarcinoma in a Non-Oriental Asian population. METHODS: In this retrospective analysis, data from 72 Non-Oriental Asian patients, who underwent 93 18F-FDG PET-CT studies, were evaluated. All patients had histopathologically proven gastric adenocarcinoma, for which they had undergone primary treatment. PET-CT was performed for suspected recurrence or for post-therapy surveillance. PET-CT findings were analysed on a per-patient and per-region basis (local/lymph node/liver/lung/bone/others). A combination of clinical follow-up (minimum 6 months; range: 6-36 months), imaging follow-up and/or histopathology (when available) was taken as the reference standard. Sensitivity, specificity and predictive values were calculated for PET-CT on both a per-study and per-lesion basis. RESULTS: The mean patient age was 52.8 ± 11.8 years (male/female: 52/20). Out of 93 PET-CT studies, 56 (60.2%) were positive and 37 (39.8%) were negative for recurrent disease. On per-study-based analysis, 18F-FDG PET-CT has a sensitivity, specificity and accuracy of 95.9, 79.5 and 88.1%, respectively. The accuracy of 18F-FDG PET-CT was 89.2% for local recurrence, 94.6% for lymph nodes, 96.7% for liver, 96.7% for lung, 98.9% for bone and 98.9% for other sites. The accuracy of 18F-FDG PET-CT was lower for local recurrence as compared with that for liver (P=0.012) and bone (P=0.012). No significant difference was found in the diagnostic accuracies for other regions. CONCLUSION: 18F-FDG PET-CT is highly sensitive and specific for detecting recurrence in patients with gastric adenocarcinoma. It shows high accuracy both on a per-patient and per-lesion basis.

Postorchiectomy intrascrotal hematoma mimicking local recurrence on 18F-FDG PET/CT: a diagnostic dilemma.

Intratesticular hematomas usually develop immediately after orchiectomy is done for testicular tumors and may last for 3 to 6 weeks or longer. They may be confused with local recurrence on clinical examination and imaging. We present the (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) images of a 30-year-old man who underwent right radical transinguinal orchiectomy for seminoma. PET/CT done 8 weeks after orchiectomy revealed a soft tissue lesion in the right scrotum with increased FDG uptake, suspicious for local recurrence. However, on color Doppler ultrasonography of the scrotum, the mass was confirmed to be a hematoma.

Imaging thrombus in cancer patients with FDG PET-CT.

The incidence of thrombosis in patients with underlying primary malignancy is high. The thrombus may be the more common venous thromboembolism (VTE) or the rare tumour thrombus. VTE is a common entity in cancer patients and is managed with anticoagulant therapy, while tumour thrombosis requires aggressive multimodality management. Conventional imaging modalities, including ultrasonography, venography, contrast-enhanced computed tomography, and magnetic resonance imaging, are used routinely in such cases. With its increasing use in oncology, more and more such thrombi are encountered on 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT). Accurate characterisation of these lesions is of utmost importance owing to complementary functional information which it provides. FDG PET-CT has been found to be helpful in this context. This pictorial review discusses and illustrates the imaging features of thrombosis on FDG PET-CT.

Role of FDG-PET/CT in detection of recurrent disease in colorectal cancer.

BACKGROUND: One-third of patients with colorectal cancer (CRC) are likely to have a recurrence within the first 1-2 years. Conventional imaging modalities have limitations in detecting recurrent disease early. The purpose of this study was to assess the usefulness of fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in the detection of recurrence in patients with CRCs. METHODS: One hundred and eighty-three patients, who were earlier treated with surgery and/or chemotherapy/radiotherapy, underwent 269 PET/CT studies for the detection of recurrence. The final diagnosis was made on the basis of histological analysis or clinical and imaging follow-up. RESULTS: The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value in detecting recurrent CRC using F-FDG-PET/CT were 87, 90, 88, 93, and 80%, respectively. PET/CT was found to have limitations in detecting microscopic disease and small-sized lesions. The common cause of false-positive PET/CT results was infective and inflammatory pathology in our setup. CONCLUSION: PET/CT showed high sensitivity, specificity, and accuracy for the detection of recurrent disease in patients, who were earlier treated for CRC. PET/CT can be considered as a useful diagnostic tool in these patients.