The Role of 18F-FDG PET/CT in Evaluating the Efficacy of Radiofrequency Ablation in Metastatic and Primary Liver Tumors: Preliminary Results.

OBJECTIVES: The aim of the study was to investigate the role of 18fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for evaluating the efficacy of radiofrequency ablation (RFA) in primary and metastatic liver tumors compared with contrast-enhanced ultrasound examination (CEUS) and to find its place in overall staging and the follow-up diagnostic algorithm. METHODS: PET/CT examinations were performed 2 months after RFA for 20 patients with a total of 34 liver lesions. CEUS was performed within 10 days after PET/CT, and the results were compared. Seven patients were staged with PET/CT and the others with a contrast-enhanced CT. RESULTS: A total of 48 18F-FDG PET/CT examinations were performed. We observed complete response in 8 patients (40%), 2 patients (10%) had stable disease, one (5%) had partial response, and 9 patients (45%) had progression (including 2 cases with extrahepatic involvement). Compared with CEUS, there was a mismatch in 3 cases. Five patients underwent additional RFA for 7 lesions. CONCLUSION: According to our preliminary data, PET/CT may be a valuable method, with comparable or eventually even better sensitivity than CEUS, for early evaluation of the efficacy of RFA for the treatment of metastatic and primary liver lesions and planning of future treatment. PET/CT might be recommended as a staging method before undergoing RFA of liver lesions for determining the local extent of the disease in the liver in combination with CEUS with an advantage in visualization of extrahepatic involvement. However, more patients need to be investigated in order to demonstrate and confirm the obtained results with certainty.

18F-FDG PET/CT in Patients with Parenchymal Changes Attributed to Radiation Pneumonitis

Objectives: Radiation pneumonitis (RP) can be an adverse complication of radiotherapy (RT) and can limit the application of the already planned radiation dose. It is often associated with RT of lung carcinoma and is occasionally caused by radiation therapy of breast carcinoma and lymphomas located in the mediastinum. Positron emission tomography/computed tomography (PET/CT) emerges lately as a prospective modality for early diagnostics of RP. The aim of this study was to summarize the initial data from diagnostic application of PET/CT in patients suspicious of RP and to derive criteria, which can help differentiate RP from early recurrence of the disease and/or residual tumor. Methods: The current study included 23 patients who had metabolic (PET) and anatomical (CT) changes consistent with RP. We additionally defined metabolic activity (SUVmax) in the lung parenchyma of 20 patients without RT. Results: All patients had increased metabolic activity in the lung parenchyma involved in the irradiated area with a mean SUVmax 3.45 (ranging between 1 and 7.1). The control group had a physiological background metabolic activity-SUVmax 0.61 +/- 0.11. Conclusion: Metabolic changes in patients suspicious of RP involved diffusely increased metabolic activity coinciding with the anatomical changes in the irradiated area. Three out of 23 patients had a proven recurrence of the primary neoplastic process in the irradiated area. The metabolic changes in those patients involved an increase in metabolic activity at follow-up or lack of tendency towards normalization after chemotherapy, which implied the existence of viable tumor cells. Our initial experience in the diagnostic application of 18F-FDG PET/CT in patients suspicious of RP allows us to summarize the following: PET/CT is a reliable imaging modality in the diagnostics of RP. Through its sequential use, we can differentiate inflammatory changes related to RP from early recurrence of the primary neoplastic process.

Results of a Prospective Multicenter International Atomic Energy Agency Sentinel Node Trial on the Value of SPECT/CT Over Planar Imaging in Various Malignancies.

UNLABELLED: We aimed to assess the additional value of SPECT/CT over planar lymphoscintigraphy (PI) in sentinel node (SN) detection in malignancies with different lymphatic drainage such as breast cancer, melanoma, and pelvic tumors. METHODS: From 2010 to 2013, 1,508 patients were recruited in a multicenter study: 1,182 breast cancer, 262 melanoma, and 64 pelvic malignancies (prostate, cervix, penis, vulva). PI was followed by SPECT/CT 1-3 h after injection of (99m)Tc-colloid particles. Surgery was performed the same or next day. RESULTS: Significantly more SNs were detected by SPECT/CT for breast cancer (2,165 vs. 1,892), melanoma (602 vs. 532), and pelvic cancer (195 vs. 138), all P < 0.001. The drainage basin mismatch between PI and SPECT/CT was 16.5% for breast cancer, 11.1% for melanoma, and 51.6% for pelvic cancers. Surgical adjustment was 17% for breast cancer, 37% for melanoma, and 65.6% for pelvic cancer. CONCLUSION: SPECT/CT detected more SNs and changed the drainage territory, leading to surgical adjustments in a considerable number of patients in all malignancies studied but especially in the pelvic cancer group because of this group's deep lymphatic drainage. We recommend SPECT/CT in all breast cancer patients with no SN visualized on PI, all patients with melanoma of the head and neck or trunk, all patients with pelvic malignancies, and those breast cancer and melanoma patients with unexpected drainage on PI.

Is there an advantage in performing a combined examination: diuretic renal scintigraphy and low dose computed tomography compared to the separate use of these methods in urolithiasis.

Ultrasonography (US), radiography of the kidneys, ureters and bladder (RKUB), intravenous urography (IVU) and especially non-enchanced CT are well established diagnostic modalities in screening patients with urolithiasis, while not always fully diagnostic especially when obstructive uropathy or calculous pyelonephritis are present . Diuretic renal scintigraphy (DRS) can determine obstruction, may differentiate between complete or partial, acute or chronic obstruction, but can not specify the cause and often the location of obstruction. The imaging protocol, including DRS with technetium-99m-mercaptylacetyltriglycine ((99m)Tc-MAG3) and single photon emission tomography/computed tomography (SPET/CT) of the kidneys, ureters, and urinary bladder allows for both functional and morphological information, visualization of renal stones and possible renal complications. The main advantages and limitations of this combined examination are discussed and the test is compared to the separate use of DRS and low dose of CT, in urolithiasis.