Harmandeep Singh

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.

Bone scintigraphy in breast cancer: added value of hybrid SPECT-CT and its impact on patient management.

PurposeTo evaluate the incremental value of single-photon emission computed tomography—computed tomography (SPECT-CT) over planar scintigraphy and SPECT alone for equivocal bone scintigraphy lesions in patients with breast cancer and to assess its impact on patient management. MethodsA total of 102 patients with 115 equivocal lesions on planar scintigraphy underwent SPECT and SPECT-CT of selected volume. 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 was constructed for each modality. Clinical/imaging follow-up and/or histopathology were taken as the reference standard. ResultsThere were 52 indeterminate lesions on planar scintigraphy, 15 on SPECT, and three on SPECT-CT. Area under the curve for SPECT-CT was significantly larger compared with planar scintigraphy (P<0.001) and SPECT (P=0.033). This improvement was mostly for lytic lesions (P<0.0001). In patients (n=67) in whom the lesions under evaluation were the only lesions and hence whose management was decided, SPECT-CT was superior to SPECT (P=0.045) and planar scintigraphy (P <0.001). ConclusionSPECT-CT is better than planar scintigraphy and SPECT alone for characterizing equivocal bone scintigraphy lesions in patients with breast cancer and can have a significant impact on patient management.

Role of FDG PET-CT in detecting recurrence in patients with uterine sarcoma: comparison with conventional imaging.

PurposeThe purpose of the present study was to evaluate the role of 18F-fluorodeoxyglucose (FDG) PET-CT in detecting recurrent disease in posttherapy patients of uterine sarcoma and compare the same with conventional imaging (CI). MethodsA total of 15 FDG PET-CT studies were acquired in 12 posttherapy uterine sarcoma patients. The images were evaluated by two experienced nuclear medicine physicians in consensus. Clinical/imaging follow-up (minimum 6 months) and histopathology were taken as the reference standard. All the patients had also undergone CI (CT or MRI or ultrasonography) of the chest, abdomen, and pelvis. The diagnostic accuracy of FDG PET-CT was calculated and compared with that of CI. ResultsThe median age of the patients was 51.5 years (interquartile range: 47.5–53). Histopathology was leiomyosarcoma in six, carcinosarcoma in five, and endometrial stromal sarcoma in one patient. Six FDG PET-CT studies were carried out for suspected recurrence and nine for posttherapy surveillance. Six FDG PET-CTs were positive and nine were negative for recurrence. The sensitivity, specificity, and accuracy of FDG PET-CT were 85.7, 100, and 93.3%, respectively, on per study-based analysis, and 80, 100, and 83.3% on per lesion-based analysis. PET-CT showed higher sensitivity and specificity compared with CI for both study-based and lesion-based analysis. However, no significant difference was found between FDG PET-CT and CI either in the study-based or in the lesion-based analysis (P not significant). ConclusionFDG PET-CT is a highly sensitive and specific modality for detecting recurrence in posttherapy patients with uterine sarcoma. However, it provides no significant advantage over CI for this purpose.

Carcinoma endometrium: role of 18-FDG PET/CT for detection of suspected recurrence.

Objective Recurrent carcinoma endometrium has a poor prognosis. However, successful salvage with long-term survival has been achieved after hormone therapy, radical surgery, and radiotherapy/chemotherapy in patients with recurrent disease. Conventional imaging (CI) and tumor marker have limited accuracy for detecting recurrence in these patients. The aim of the present study was to evaluate the role of 18-flurodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) in patients suspected to have recurrence of carcinoma endometrium. Methods In this retrospective study, total 101 patients were evaluated. All patients had undergone surgery with/without adjuvant therapy (chemotherapy/radiotherapy/both) for histologically proven carcinoma endometrium. They underwent 18-FDG PET/CT studies for suspected recurrence. Comparable CI (contrast-enhanced CT and/or magnetic resonance imaging) was available for 76 patients. Results of FDG PET/CT were confirmed with clinical/imaging follow-up and/or histopathology. Results The mean age was 56.9 ± 8.6 years. 18-FDG PET/CT was positive for recurrence in 51 (50.5%) patients and negative in 50 (49.5%). Locoregional disease was observed in 24 patients, metastatic disease was observed in 10, and 17 showed both locoregional and metastatic disease. The sensitivity, specificity, positive and negative predictive values, and accuracy of 18-FDG PET/CT were 88.9%, 93.6%, 94.1%, 88%, and 91%, respectively. 18-FDG PET/CT showed strong positive correlation with final diagnosis based on reference standard (&kgr; 0.823; P = 0.0001). Compared to CI, 18-FDG PET/CT has much higher specificity (62% vs. 96.4%), and accuracy (76.3% vs. 92.1%), with comparable sensitivity (85.1% vs. 89.5%). Conclusion 18-FDG PET/CT is a highly sensitive and specific modality for detecting recurrence in post-therapy patients of carcinoma endometrium with suspected recurrence. It performs better than CI.

PET/CT imaging of neuroendocrine tumors with 68Gallium-labeled somatostatin analogues: An overview and single institutional experience from India

Neuroendocrine tumors (NETs) are rare neoplasms characterized by overexpression of somatostatin receptors (SSTRs). Functional imaging plays a crucial role in management of NETs. Recently, positron emission tomography/computed tomography (PET/CT) with 68Gallium (68Ga)-labeled somatostatin analogues has shown excellent results for imaging of NETs and better results than conventional SSTR scintigraphy. In this review we have discussed the utility of 68Ga-labeled somatostatin analogue PET/CT in NETs for various established and potential indications. In addition we have also shared our own experience from a tertiary care center in India.

Role of FDG PET-CT in recurrent renal cell carcinoma.

AimTo determine the efficacy of positron emission tomography-computed tomography using F-18 fluoro-deoxy-glucose (F-18 FDG PET-CT) in diagnosing the recurrence of renal cell carcinoma (RCC) in patients treated earlier with partial or radical nephrectomy. MethodsWe assessed 63 patients with suspected recurrent RCC after nephrectomy. PET-CT findings were interpreted as positive if the focal area of FDG uptake in the abdomen or outside the abdomen was more than the surrounding background tissue. The final diagnosis of the recurrence of RCC was based on histological examination and/or clinical follow-up and conventional imaging modalities. ResultsA total of 103 PET-CT studies were done in these 63 patients, of which 63 studies were true positive, 30 studies were true negative, seven studies were false negative and remaining three studies were false positive. In 63 true-positive scans, PET-CT showed 109 lesions. Of these, 28 lesions were in the lungs, 21 lesions were at a locoregional site, 21 were in the bones, 12 in the retroperitoneal lymph nodes and 27 at other sites. The sensitivity, specificity and accuracy of PET-CT were 90, 91 and 90%, respectively. ConclusionOur results seem to confirm the useful role of PET-CT in the evaluation of post-surgical recurrence in patients who had undergone radical surgery for RCC.

Utility of 18F-FDG PET-CT in staging and restaging of patients with malignant salivary gland tumours: a single-institutional experience

ObjectiveThe aim of this study was to evaluate the clinical utility of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography–computed tomography (PET-CT) in staging and restaging of patients with malignant primary salivary gland tumours. MethodsData pertaining to 30 patients (age: 43.8±16.8 years; male/female: 20/10) with histopathologically proven malignant primary salivary gland tumours who underwent 36 18F-FDG PET-CTs were retrospectively analysed. Ten PET-CTs were performed for staging and 26 for restaging. The primary site was the parotid gland in 22 patients, the submandibular gland in seven and the minor salivary gland in one patient. 18F-FDG PET-CT images were revaluated by two nuclear medicine physicians in consensus. Findings were grouped into local disease, nodal disease and distant metastasis. Results were compared with those of conventional imaging modalities [CIM (CT/ultrasound/bone scintigraphy)] when available (n=28). Clinical or imaging follow-up (minimum 6 months) data along with histopathological information (when available) were taken as the reference standard. ResultsOverall, 25 PET-CTs were positive and 11 were negative for disease. 18F-FDG PET-CT showed local disease in 21 patients, nodal disease in 17 and distant metastasis in nine (lungs, four; liver, three; bones, four; and thyroid, one). Twenty-three PET-CTs were true positive, nine were true negative, two were false positive and two were false negative. The overall sensitivity of 18F-FDG PET-CT was 92%, specificity was 82%, positive predictive value was 92%, negative predictive value was 82% and accuracy was 89%. No significant difference was seen in the accuracy of PET-CT between the staging and restaging groups (100 vs. 85%; P=0.468). In patients for whom comparable CIM data were available (n=28), PET-CT did not show any significant advantage over CIM (P=0.012) but was more specific (71 vs. 43%). Conclusion 18F-FDG PET-CT shows high accuracy in staging and restaging of patients with malignant primary salivary gland tumours. It is more specific than CIM 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 131I-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 131I-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 (&kgr; = 0.966) as compared with PS (&kgr; = 0.815) and SPECT (&kgr; = 0.826). Conclusions 131I-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 123I-MIBG is not available.

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.

Positron emission tomography-computed tomography in the management of lung cancer: An update

This communication presents an update on the current role of positron emission tomography-computed tomography (PET-CT) in the various clinical decision-making steps in lung carcinoma. The modality has been reported to be useful in characterizing solitary pulmonary nodules, improving lung cancer staging, especially for the detection of nodal and metastatic site involvement, guiding therapy, monitoring treatment response, and predicting outcome in non-small cell lung carcinoma (NSCLC). Its role has been more extensively evaluated in NSCLC than small cell lung carcinoma (SCLC). Limitations in FDG PET-CT are encountered in cases of tumor histotypes characterized by low glucose uptake (mucinous forms, bronchioalveolar carcinoma, neuroendocrine tumors), in the assessment of brain metastases (high physiologic 18F-FDG uptake in the brain) and in cases presenting with associated inflammation. The future potentials of newer PET tracers beyond FDG are enumerated. An evolving area is PET-guided assessment of targeted therapy (e.g., EGFR and EGFR tyrosine kinase overexpression) in tumors which have significant potential for drug development.