Diagnostic accuracy of 18F-FDG PET/CT for detecting recurrence in patients with primary skeletal Ewing sarcoma.

PURPOSE: To evaluate the diagnostic accuracy of (18)F-FDG PET/CT for detecting recurrence in patients with primary skeletal Ewing sarcoma. METHODS: We retrospectively analysed data from 53 patients (age 20.1 ± 10.5 years, 39 male) who had undergone 71 (18)F-FDG PET/CT studies for suspected recurrence (52 studies) or for routine follow-up (19 studies) after primary therapy of skeletal Ewing sarcoma. (18)F-FDG PET/CT studies were evaluated qualitatively and quantitatively (maximum standardized uptake value, SUVmax) by two nuclear medicine physicians in consensus. Sensitivity, specificity, predictive values and accuracy were calculated on per study basis. Clinical/imaging follow-up (minimum 6 months) and/or histopathology (when available) were taken as the reference standard. RESULTS: Of the total of 71 (18)F-FDG PET/CT studies, 42 (59.1%) were positive for recurrence and 29 (40.9%) were negative for recurrence. Local recurrence was most common (38 studies) followed by bone metastasis (9 studies), and node and lung metastasis (2 studies each). Of the 71 studies, 38 were true-positive, 27 were true-negative, 4 were false-positive and 2 were false-negative. Overall per study based sensitivity was 95%, specificity was 87%, PPV was 90%, NPV was 93% and accuracy was 91.5%. No significant difference was found in the accuracy of PET/CT between the suspected recurrence group and the routine follow-up group (94% vs. 84%; P = 0.390). Overall mean lesion SUVmax was 7.8 ± 4.1 (range 1.9-17.2). No site-based difference was found in SUVmax. CONCLUSION: (18)F-FDG PET/CT demonstrates high diagnostic accuracy for detecting recurrence in patients with primary skeletal Ewing sarcoma, when it is suspected (clinically or on imaging) or during routine follow-up.

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.

Primary rhabdomyosarcoma of pulmonary artery: 18F-FDG PET/CT for detecting recurrence in a rare tumor.

Primary pulmonary artery rhabdomyosarcomas are very rare tumors with a small number of cases reported in the literature. Here we show (18)F-flurodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) images of a 58-year-old man with left pulmonary artery rhabdomyosarcoma who had undergone surgery for the primary tumor followed by chemotherapy. Restaging FDG PET/CT showed local recurrence and pulmonary metastasis. This case highlights that FDG PET/CT can be useful for restaging rare tumors such as pulmonary artery rhabdomyosarcoma.

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.