Split-dose technique for FDG PET/CT-guided percutaneous ablation: a method to facilitate lesion targeting and to provide immediate assessment of treatment effectiveness.

PURPOSE: To describe a split-dose technique for fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT)-guided ablation that permits both target localization and evaluation of treatment effectiveness. MATERIALS AND METHODS: Institutional review board approved the study with a waiver of consent. From July to December 2011, 23 patients (13 women, 10 men; mean age, 59 years; range, 35-87 years) with 29 FDG-avid tumors (median size, 1.4 cm; range, 0.6-4.4 cm) were targeted for ablation. The location of the lesion was the liver (n = 23), lung (n = 4), adrenal gland (n = 1), and thigh (n = 1). Radiofrequency ablation was performed in 17 lesions; microwave ablation, in six; irreversible electroporation, in five; and cryoablation, in one. The pathologic condition of the tumor was metastatic colorectal adenocarcinoma in 18 lesions, primary hepatocellular carcinoma in one lesion, and a variety of metastatic tumors in the remaining 10 lesions. A total of 4 mCi (148 MBq) of FDG was administered before the procedure for localization and imaging guidance. At completion of the ablation, an additional 8 mCi (296 MBq) of FDG was administered to assess ablation adequacy. Results of subsequent imaging follow-up were used to determine if postablation imaging after the second dose of FDG reliably helped predict complete tumor ablation. Descriptive statistics were used to summarize the results. RESULTS: Twenty-eight of 29 (97%) ablated lesions showed no residual FDG activity after the second intraprocedural FDG dose. One patient with residual activity underwent immediate biopsy that revealed residual viable tumor and was immediately re-treated. Follow-up imaging at a median of 155 days (range, 92-257 days) after ablation showed local recurrences in two (7%) lesions that were originally negative at postablation PET. CONCLUSION: Split-dose FDG PET/CT may be a useful tool to provide both guidance and endpoint evaluation, allowing an opportunity for repeat intervention if necessary. Further work is necessary to validate these concepts.

Subperitoneal adenomucinosis following proctocolectomy for ulcerative colitis.

Adenomucinosis is a rare condition characterized by accumulation of large volumes of mucin, typically related to mucinous neoplasms of the appendix within the peritoneal space. Extraperitoneal adenomucinosis is an uncommon variant where mucin accumulates outside the peritoneal space and usually arises following surgery for mucinous appendiceal neoplasms. This is a case of subperitoneal adenomucinosis resulting from retention of a small fragment of rectal mucosa following proctocolectomy for ulcerative colitis 16 years prior. The patient presented with a slow-growing boggy perineal mass. Contrast-enhanced magnetic resonance imaging (MRI) showed the mass to be localized to the pelvis, without solid enhancing components, and correctly facilitated local surgical excision without the risk of peritoneal dissemination and accurately predicted benignity.

Magnetic resonance enteroclysis compared with conventional enteroclysis and computed tomography enteroclysis: a critically appraised topic.

Recent advances in CT and MR technology, particularly the advent of multidetector CT (MDCT), the advent of rapidly changing gradients in industry standard MRI scanners, enabling ultrafast sequences, have led to an expansion in the role of cross sectional imaging in the investigation of small bowel disorders. We conducted an evidence-based review of MR enteroclysis (MRE) and how it performs in comparison to CT enteroclysis (CTE) and the gold standard of conventional enteroclysis (CE) for diagnosis of small bowel Crohn's disease and small bowel neoplasia. We used the standard 5 step evidence-based medicine method of ask, search, appraise, apply and evaluate. We found 3 relevant level 1B studies, and one level 3B study. No studies evaluating MRE in small bowel neoplasia were found. MRE does not perform as well as CE in evaluation of fine mucosal detail, but the additional extraluminal detail, and absence of ionising radiation enhances its overall performance. It was not possible to establish the relative diagnostic performances of MRE and CTE from existing literature. CTE does involve patient irradiation. For patients in whom jejunal intubation and enteroclysis is considered to evaluate the small bowel, MRE should be considered the first-line investigation, local resources and expertise permitting.

FDG PET/CT demonstrates the effectiveness of isolated limb infusion for malignant melanoma.

A 43-year-old woman presented with a nodular melanoma treated with wide excision, split skin graft, and sentinel node biopsy. At 2-year follow up, she was noted to have clinical recurrence at the excision site. FDG PET/CT demonstrated in-transit metastasis in her left thigh in addition to disease at the site of the sentinel node biopsy. Isolated limb infusion was performed with melphalan and dactinomycin. PET/CT at 5 weeks demonstrated resolution of the in-transit metastasis and the disease at the excision site. This report of PET/CT demonstrates the effectiveness of chemotherapy for malignant melanoma delivered by isolated limb infusion.

PET/CT-guided interventions: personnel radiation dose.

PURPOSE: To quantify radiation exposure to the primary operator and staff during PET/CT-guided interventional procedures. METHODS: In this prospective study, 12 patients underwent PET/CT-guided interventions over a 6 month period. Radiation exposure was measured for the primary operator, the radiology technologist, and the nurse anesthetist by means of optically stimulated luminescence dosimeters. Radiation exposure was correlated with the procedure time and the use of in-room image guidance (CT fluoroscopy or ultrasound). RESULTS: The median effective dose was 0.02 (range 0-0.13) mSv for the primary operator, 0.01 (range 0-0.05) mSv for the nurse anesthetist, and 0.02 (range 0-0.05) mSv for the radiology technologist. The median extremity dose equivalent for the operator was 0.05 (range 0-0.62) mSv. Radiation exposure correlated with procedure duration and with the use of in-room image guidance. The median operator effective dose for the procedure was 0.015 mSv when conventional biopsy mode CT was used, compared to 0.06 mSv for in-room image guidance, although this did not achieve statistical significance as a result of the small sample size (p = 0.06). CONCLUSION: The operator dose from PET/CT-guided procedures is not significantly different than typical doses from fluoroscopically guided procedures. The major determinant of radiation exposure to the operator from PET/CT-guided interventional procedures is time spent in close proximity to the patient.

Coronary ostial involvement in acute aortic dissection: detection with 64-slice cardiac CT.

A 41-year-old man collapsed after lifting weights at a gym. Following admission to the emergency department, a 64-slice cardiac computed tomography (CT) revealed a Stanford Type A aortic dissection arising from a previous coarctation repair. Multiphasic reconstructions demonstrated an unstable, highly mobile aortic dissection flap that extended proximally to involve the right coronary artery ostium. Our case is an example of the application of electrocardiogram-gated cardiac CT in directly visualizing involvement of the coronary ostia in acute aortic dissection, which may influence surgical management.