Correlation between early 18F-FDG PET/CT response to BRAF and MEK inhibition and survival in patients with BRAF-mutant metastatic melanoma.

PURPOSE: Metabolic response to treatment measured by fluorine-18 fluorodeoxyglucose ((18)F-FDG) PET has prognostic implications in many cancers. This study investigated the association between survival and early changes on (18)F-FDG PET/computed tomography (CT) for patients with BRAF-mutant melanoma receiving combined BRAF and MEK inhibition therapy. MATERIALS AND METHODS: Overall, 24 patients with advanced BRAF-mutant melanoma were included. Patients were treated with a BRAF inhibitor (vemurafenib or dabrafenib) and a MEK inhibitor (cobimetinib or trametinib), and were imaged at baseline and shortly thereafter with (18)F-FDG PET/CT. Each scan yielded two values of maximum standardized uptake value (SUVmax): one for the most metabolically active focus and one for the least responsive focus. Short-term treatment response was assessed by evaluating the target lesions using the EROTC criteria. A Cox proportional hazards model was used to examine associations between overall survival (OS) and progression-free survival (PFS) and changes in SUVmax. RESULTS: The mean time to follow-up (18)F-FDG PET/CT was 26 days. At follow-up, two patients achieved a complete response. For the most metabolically active focus, 22 patients showed a partial response. For the least responsive focus, 18 patients showed a partial response, two had stable disease, and two had progressive disease.A total of 16 patients were alive at the end of the study. For the most metabolically active tumor, no association was observed between changes in SUVmax and OS (P=0.73) or PFS (P=0.17). For the least responsive tumor, change in SUVmax was associated with PFS [hazard ratio (HR)=1.34, 95% confidence interval (CI): 1.06-1.71, P=0.01], but not OS (P=0.52). The ECOG score was associated with OS (HR=11.81, 95% CI: 1.42-97.60, P=0.02) and PFS (HR=24.72, 95% CI: 3.23-189.42, P=0.002). CONCLUSION: Change in SUVmax for the least responsive tumor and baseline functional performance may be useful prognostic indicators for PFS in patients with BRAF-mutant melanoma.

Parathyroid Imaging with Simultaneous Acquisition of 99mTc-Sestamibi and 123I: The Relative Merits of Pinhole Collimation and SPECT/CT.

UNLABELLED: The objective of this study was to determine the relative utility of 3 state-of-the-art parathyroid imaging protocols: single-time-point simultaneous acquisition of (99m)Tc-sestamibi and (123)I images with pinhole collimation in the anterior and bilateral anterior oblique projections, single-time-point simultaneous acquisition of (99m)Tc-sestamibi and (123)I images with SPECT/CT, and the combination of the first and second protocols. METHODS: Fifty-nine patients with surgical proof of parathyroid adenomas were evaluated retrospectively. All 3 protocols included perfectly coregistered subtraction images created by subtracting the (123)I images from the (99m)Tc-sestamibi images, plus an anterior parallel-hole collimator image of the neck and upper chest. The pinhole protocol was performed first, followed by the SPECT/CT protocol. Three image sets were derived from each study in each patient according to the above protocols. Two experienced observers recorded the size, location, and degree of certainty of any identified lesion. RESULTS: The 59 patients had 61 adenomas. For the 2 observers combined, the localization success rate was 88% for the pinhole protocol, 69% for the SPECT/CT protocol, and 81% for the combined protocol. The pinhole protocol detected more adenomas than the SPECT/CT protocol and missed fewer adenomas than either the SPECT/CT protocol or the combined pinhole and SPECT/CT protocol (P < 0.01). The 2 protocols that included SPECT/CT provided superior anatomic information relative to the location and size of the parathyroid adenomas. CONCLUSION: The pinhole protocol localized significantly more adenomas than the SPECT/CT protocol. However, the protocols that included SPECT/CT provided more anatomic information than pinhole imaging alone.

Anti-CTLA4 antibody therapy related complications on FDG PET/CT.

Anti-cytotoxic T-lymphocyte antigen-4 monoclonal antibody therapy is a new class of drug which has demonstrated increased overall survival in patients with metastatic melanoma. Anti-CTLA-4 antibody therapy inhibits the CTLA-4 inhibitory signal, thereby enhancing the anti-tumor response of the cytotoxic T lymphocytes. This response can lead to a variety of immune-related adverse events. Many of these events are present on follow-up PET/CT examinations performed to assess response to therapy. It is important for the interpreting physician to be aware of the findings on PET/CT to avoid diagnosing adverse events as progressive disease and to alert clinicians regarding these complications.

SPECT/CT of metastatic struma ovarii.

A 41-year-old woman presented with multiple right lower quadrant masses which were removed and consistent with metastatic follicular thyroid cancer. Thyroidectomy revealed no primary malignancy and evaluation of her ovaries was positive for struma ovarii. The patient was diagnosed with metastatic struma ovarii stage IV. Nine days following the patient's second therapy with I for recurrent disease, planar and SPECT/CT imaging demonstrated multiple I avid peritoneal nodules. At least one of them, located along the medial margin of the spleen, would have been difficult to diagnose without hybrid SPECT/CT imaging.

18F-FDG PET/CT evaluation of children and young adults with suspected spinal fusion hardware infection.

BACKGROUND: Evaluation of the child with spinal fusion hardware and concern for infection is challenging because of hardware artifact with standard imaging (CT and MRI) and difficult physical examination. Studies using (18)F-FDG PET/CT combine the benefit of functional imaging with anatomical localization. OBJECTIVE: To discuss a case series of children and young adults with spinal fusion hardware and clinical concern for hardware infection. These people underwent FDG PET/CT imaging to determine the site of infection. MATERIALS AND METHODS: We performed a retrospective review of whole-body FDG PET/CT scans at a tertiary children's hospital from December 2009 to January 2012 in children and young adults with spinal hardware and suspected hardware infection. The PET/CT scan findings were correlated with pertinent clinical information including laboratory values of inflammatory markers, postoperative notes and pathology results to evaluate the diagnostic accuracy of FDG PET/CT. An exempt status for this retrospective review was approved by the Institution Review Board. RESULTS: Twenty-five FDG PET/CT scans were performed in 20 patients. Spinal fusion hardware infection was confirmed surgically and pathologically in six patients. The most common FDG PET/CT finding in patients with hardware infection was increased FDG uptake in the soft tissue and bone immediately adjacent to the posterior spinal fusion rods at multiple contiguous vertebral levels. Noninfectious hardware complications were diagnosed in ten patients and proved surgically in four. Alternative sources of infection were diagnosed by FDG PET/CT in seven patients (five with pneumonia, one with pyonephrosis and one with superficial wound infections). CONCLUSION: FDG PET/CT is helpful in evaluation of children and young adults with concern for spinal hardware infection. Noninfectious hardware complications and alternative sources of infection, including pneumonia and pyonephrosis, can be diagnosed. FDG PET/CT should be the first-line cross-sectional imaging study in patients with suspected spinal hardware infection. Because pneumonia was diagnosed as often as spinal hardware infection, initial chest radiography should also be performed.

CT-guided radiofrequency ablation of an aldosterone-secreting primary adrenal tumor in a surgically unfit patient.

Because of the speed and efficiency of laparoscopic adrenalectomy, alternative surgical procedures for adrenal adenomas are uncommon. The present report outlines the case of a young patient with an adrenal adenoma causing Conn syndrome who was a poor candidate for surgical treatment. Computed tomography (CT)-guided radiofrequency ablation of the adenoma was performed with a paraspinal approach and injection of dextrose 5% in water. After successful ablation of the 1.8-cm x 1.2-cm mass according to imaging criteria, the patient's symptoms largely resolved.