Right Ventricle Metastasis from Carcinoma Rectum: Findings on 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography.

Rectal adenocarcinoma metastasizes most commonly to the lungs and liver. Metastasis to heart, although described in literature, is a very rare phenomenon. We describe the 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) findings of a 45-year-old male who was a biopsy-proven case of adenocarcinoma rectum. Apart from metastatic disease involving liver, lungs, bone marrow, and lymph nodes, metastasis to right ventricle was also seen on PET-CT scan.

Elastofibroma Dorsi: Findings on 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography.

Elastofibroma dorsi (EFD) is a relatively rare soft-tissue pseudotumor that arises from mesenchymal tissue. We present a case of 48-year-old woman who underwent 18F fluorodeoxyglucose (FDG) positron emission tomography-computed tomography for initial staging of suspected carcinoma of the left breast. Incidental detection of soft-tissue masses showing moderate FDG uptake was seen in the bilateral infrascapular location characteristic of EFD.

Ileal Neuroendocrine Tumor With Bilateral Breast and Ovarian Metastases: Findings on 68Ga-DOTANOC PET/CT Scan.

Metastasis to the breast is a rare occurrence and constitutes less than 2% of all breast tumors. Similarly, ovarian metastases from neuroendocrine tumors are also uncommon, and if the adnexal masses are bilateral, then the chances of it being metastatic rather than being primary range from 88% to 94%. We present a case of 61-year-old woman who in the course of workup for abdominal pain and diarrhea was eventually diagnosed as ileal neuroendocrine tumor with breast, ovarian, and lymph nodal metastases on Ga-DOTANOC PET/CT scan.

Occult breast primary malignancy presenting as isolated axillary lymph node metastasis - early detection of primary site by 18F-FDG PET/CT.

Breast cancer patients rarely present with isolated axillary lymph node metastasis without any clinical or radiological evidence of primary tumor. Identification of the primary site of tumor helps in planning appropriate patient management which has definite impact on patient's survival. We present here a case of 30-year-old female who presented with isolated right axillary lymph node metastasis with no evidence of primary tumor clinically. Conventional imaging modalities were negative for primary site. She underwent whole body 18F-Flurodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and it contributed significantly in early detection of occult primary tumor in right breast.

Spectrum of Physiologic and Pathologic Skeletal Muscle (18)F-FDG Uptake on PET/CT.

OBJECTIVE: Skeletal muscle (18)F-FDG uptake on PET/CT can be either physiologic or related to a variety of different pathologic conditions. FDG PET/CT can be used for assessment of primary and metastatic tumors and infective or inflammatory conditions affecting the musculature. CONCLUSION: In this article, we describe the various causes and patterns of skeletal muscle FDG uptake. Familiarity with these patterns is essential for proper interpretation of clinical FDG PET/CT images.

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 (SUV(max)). 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 SUV(max) 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 SUV(max) 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.

Evaluation of (68)Ga-DOTANOC PET/CT imaging in a large exclusive population of pancreatic neuroendocrine tumors.

PURPOSE: To evaluate the diagnostic accuracy of (68)Ga-DOTANOC PET/CT imaging in a large exclusive population of pancreatic neuroendocrine tumors (NETs). METHODS: Data of 141 (mean age 46.2 ± 15.2 years) patients who underwent 178 (68)Ga-DOTANOC PET/CT studies for diagnosis/staging (n = 88) and restaging (n = 90) of pancreatic NET were retrospectively analyzed. PET/CT results were compared to conventional imaging (CIM) when available (n = 86). Histopathology and/or clinical/imaging follow-up (minimum 6 months) were used as reference standard. RESULTS: The overall sensitivity, specificity, and accuracy of (68)Ga-DOTANOC PET/CT were 85.7%, 79.1%, and 84.8%. The corresponding values were 73%, 50%, and 70.4% for diagnosis/staging groups and 98.6%, 100%, and 98.8% for restaging groups. The accuracy was significantly higher for restaging as compared to diagnosis/staging (P < 0.0001) and in non-insulinoma tumors than insulinomas (P < 0.0001). The SUVmax of primary tumors was significantly higher than metastatic lesions overall (P = 0.001), as well as in diagnosis/staging (P = 0.041) and restaging (P = 0.0003) subgroups. When available, CIM was less specific than (68)Ga-DOTANOC PET/CT (P < 0.001) and showed fewer lesions. CONCLUSIONS: (68)Ga-DOTANOC PET/CT is useful for diagnosis/staging and restaging of patients with pancreatic NET. It demonstrates more lesions compared to CIM and is more specific.

Comparison of the prognostic values of 68Ga-DOTANOC PET/CT and 18F-FDG PET/CT in patients with well-differentiated neuroendocrine tumor.

PURPOSE: To determine the prognostic value of (68)Ga-DOTANOC PET/CT in patients with well-differentiated neuroendocrine tumor (NET), and to compare the prognostic value with that of (18)F-FDG PET/CT and other conventional clinicopathological prognostic factors. METHODS: Data from 37 consecutive patients (age 46.6 ± 13.5 years, 51% men) with well-differentiated NET who underwent (68)Ga-DOTANOC PET/CT and (18)F-FDG PET/CT were analyzed. All patients underwent a baseline visit with laboratory and radiological examinations. Clinical and imaging follow-up was performed in all patients. Progression-free survival (PFS) was measured from the date of the first PET/CT scan to the first documentation of progression of disease. RESULTS: (68)Ga-DOTANOC PET/CT was positive in 37 of the 37 patients and (18)F-FDG PET/CT was positive in 21. During follow-up 10 patients (27%) showed progression of disease and 27 (73%) showed no progression (24 stable disease, 3 partial response). The median follow-up was 25 months (range 2 - 52 months). Among the variables evaluated none was significantly different between the progressive disease and nonprogressive disease groups, with only SUVmax on (68)Ga-DOTANOC PET/CT being borderline significant (P = 0.073). In the univariate analysis for PFS outcome, SUVmax on (68)Ga-DOTANOC PET/CT (HR 0.122, 95% CI 0.019 - 0.779; P = 0.026) and histopathological tumor grade (HR 4.238, 95% CI 1.058 - 16.976; P = 0.041) were found to be associated with PFS. Other factors including age, sex, primary site, Ki-67 index, TNM stage, (18)F-FDG PET/CT status (positive/negative), SUVmax on (18)F-FDG PET/CT and type of treatment were not significant. In multivariable analysis, only SUVmax on (68)Ga-DOTANOC PET/CT was found to be an independent positive predictor of PFS (HR 0.122, 95% CI 0.019 - 0.779; P = 0.026). CONCLUSION: SUVmax measured on (68)Ga-DOTANOC PET/CT is an independent, positive prognostic factor in patients with well-differentiated NET and is superior to SUVmax on (18)F-FDG PET/CT and conventional clinicopathological factors for predicting PFS.

(18)F-FDG PET/CT for initial assessment and response monitoring in a case of high grade primary lymphoma of the thyroid gland: A case report and review of literature.

Thyroid lymphoma is a rare disease entity of elderly females. Chronic lymphocytic thyroiditis is said to be the precursor of thyroid lymphoma, suggesting a role of chronic antigen stimulation in the development of the disease. We present a case of male with lymphocytic thyroiditis who presented with painless progressive neck enlargement and pathology revealed features of high grade lymphoma. Staging and posttreatment (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) was performed. This report reemphasizes the role of (18)F-FDG PET/CT in the diagnosis, staging, and assessment of therapy response in patients with extranodal lymphoma, including the primary thyroid lymphoma.

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.

18F-FDG PET/CT imaging features of Rosai Dorfman disease: a rare cause of massive generalized lymphadenopathy.

Rosai Dorfman disease (RDD) or sinus histiocytosis is a rare non-neoplastic idiopathic disease characterized by massive lymphadenopathy in young adults. Extranodal involvement is seen in 25%-43% cases. RDD is usually self-remitting. However, it mimics lymphoproliferatve disorders clinically as well as on imaging. We present the F-FDG PET/CT findings in a 46-year-old female patient with nodal RDD.

Solitary breast metastasis from recurrent gallbladder carcinoma simulating a second primary on 18F-FDG PET/CT.

Gallbladder carcinoma is characterized by poor prognosis. It spreads by direct, lymphatic, vascular, neural, intraperitoneal, and intraductal routes. The most commonly involved organ is the liver followed by regional lymph nodes. Extra-abdominal metastases are comparatively rare. We present a case of solitary breast metastasis from recurrent gallbladder carcinoma mimicking a primary breast cancer in (18)F-FDG PET/CT.

Dual tracer functional characterization of metastatic gastric carcinoid.

Because of the increasing clinical importance of gastric carcinoids and the difficulty in diagnosing them, the need for non-invasive diagnostic methods is growing. Currently, the only reliable method is upper gastrointestinal endoscopy with biopsy. We report the case of a 32-year-old male where a combination of functional imaging studies ((18)F-fluorodeoxyglucose-positron emission tomography/computed tomography [PET/CT] and (68)Ga-DOTA-NOC PET/CT) not only helped in the correct staging, but also highlighted certain important biological aspects of these tumors, which are important from the management point of view and can prognosticate the patients.

SPECT-CT for characterization of extraosseous uptake of 99mTc-methylene diphosphonate on bone scintigraphy.

Bone scintigraphy is a sensitive and popular method for imaging a wide array of benign or malignant skeletal abnormalities. However, the uptake of tracers used for bone scintigraphy may be observed in various extraosseous sites, thereby limiting its specificity. It is difficult to correctly localize such sites of uptake on planar bone scintigraphy alone. The addition of hybrid single-photon emission computed tomography-computed tomography (SPECT-CT) under such circumstances is very useful. The present essay illustrates the commonly encountered extraosseous uptake of 99mTc-methylene diphosphonate (MDP) and the usefulness of hybrid SPECT-CT in clarifying 99mTc-MDP uptake.

Primary penile lymphoma: the use of PET-CT for accurate staging and response monitoring.

Primary penile lymphoma is an extremely rare neoplasm. We present a case of 63-year-old man with painless diffuse pe- nile swelling and retention of urine. Biopsy from the penile swelling demonstrated CD20+ diffuse large B-cell lymphoma. Staging was performed using fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) and revealed a FDG avid penile mass with enlarged and FDG avid multiple inguinal and aortocaval lymph nodes. A follow-up FDG PET-CT scan after eight cycles of combination chemotherapy showed complete remission of the dis- ease. Thus, FDG PET-CT should be integrated in management protocols of rare primary penile lymphoma.

Successful localization of residual culprit tumor in a case of tumor-induced osteomalacia using 68Ga-DOTANOC PET/CT.

Tumor-induced osteomalacia (TIO) is a rare disease entity characterized by clinical pictures of recurrent multiple fractures and biochemical features of phosphaturia, hypophosphatemia, and low vitamin D levels. Most often TIO is caused by benign soft tissue tumors. The main issue in management of such patients is proper tumor localization, as these tumors are small and often located at obscure sites. We describe a case of TIO where residual disease was clinically suspected after tumor resection and subsequently detected using Ga-DOTANOC PET/CT.

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.

Preoperative characterization of indeterminate large adrenal masses with dual tracer PET-CT using fluorine-18 fluorodeoxyglucose and gallium-68-DOTANOC: initial results.

PURPOSE: We aimed to evaluate the usefulness of dual tracer positron emission tomography-computed tomography (PET-CT) with flourine-18 fluorodeoxyglucose (18F-FDG) and gallium-68 [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI3-octreotide (68Ga-DOTANOC) in preoperative characterization of large indeterminate adrenal masses. MATERIALS AND METHODS: Ten patients (four males, six females; median age, 35 years) with indeterminate, large (≥4 cm) adrenal masses were included in this prospective study. All patients underwent both 18F-FDG PET-CT and 68Ga-DOTANOC PET-CT within one week. Images were evaluated both visually and semi-quantitatively, with standardized uptake value (SUVmax) and SUVratio (SUVmax) of tumor/SUVmax) of mediastinum). Based on differential uptake pattern on 18F-FDG and 68Ga-DOTANOC, lesions were classified as cortical (18F-FDG>68Ga-DOTANOC), medullary (68Ga-DOTANOC>18F-FDG), or indeterminate (18F-FDG=68Ga-DOTANOC). Histopathology was taken as reference standard. Receiver operating characteristic (ROC) analysis was performed to find a cut-off of SUVmax) and SUVratio to differentiate cortical and medullary lesions. RESULTS: On histopathology, eight lesions were adrenocortical carcinomas, one was benign pheochromocytoma, and one was malignant pheochromocytoma. Visually, 18F-FDG PET-CT was positive in all ten lesions, while 68Ga-DOTANOC PET-CT was positive in two, both of which were pheochromocytomas. On SUVmax) based analysis, nine lesions were cortical and one was medullary. On ROC analysis, a SUVmax) cut-off of > 2.3 was obtained for 18F-FDG PET-CT and 3.6 for 68Ga-DOTANOC PET-CT for differentiating adrenal cortical and medullary lesions. The cut-off for SUVratio was 4.5 on 18F-FDG PET-CT and 11.1 on 68Ga-DOTANOC PET-CT. CONCLUSION: These preliminary results demonstrate that dual tracer PET-CT using 18F-FDG and 68Ga-DOTANOC could be informative in the preoperative characterization of large indeterminate adrenal masses.

Divergent role of (68)Ga-labeled somatostatin analogs in the workup of patients with NETs: AIIMS experience.

Neuroendocrine tumors (NETs) encompass a wide range of rare and heterogeneous neoplasms arising from the neural crest. Diagnosis of NETs is conventionally done by a combination of common clinical symptoms and biochemical evidence of hormonal excess, which these tumors are known to secrete. After a diagnosis of NET is established, a search for its localization is carried out using common morphologic imaging methods such as ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). The main problem with structural imaging is, however, its inability to distinguish between endocrine and exocrine lesions. Functional imaging of NETs started with use of iodine-131-meta-iodobenzylguanidine ((131)I-MIBG) and has come a long way since. From accurate demonstration of functioning tumors to detection of small and occult lesions, functional imaging has penetrated almost every aspect of NET management. Procedures such as (131/123)I-MIBG, (111)In-Octreoscan and others are rapidly giving way to use of PET/CT based on the superior resolution of the system and the availability of target-specific positron-emitting radiotracers. The availability of (68)Ga from generator-based radionuclide systems, namely (68)Ge/(68)Ga generators, opened up a new era of molecular imaging for NETs. A multitude of somatostatin analogs can be easily radioliganded with (68)Ga using heterocyclic macromolecular bifunctional chelating systems for targeted diagnosis of somatostatin receptor-expressing tumors, used most effectively to date for detection of NETs. This chapter focuses on our experience at the All India Institute of Medical Sciences, New Delhi regarding the divergent roles of (68)Ga-labeled somatostatin analogs in the workup of patients with NETs.