Hodgkin lymphoma: a negative interim-PET cannot circumvent the need for end-of-treatment-PET evaluation.

We examined the outcome of a cohort of patients with Hodgkin lymphoma (HL) in order to assess if fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) at the end of treatment (end-PET) can be omitted when the interim PET (int-PET) is negative. Seventy-six ABVD(adriamycin, bleomycin, vinblastine, dacarbazine)-treated patients were retrospectively included. No change in treatment was made on the basis of int-PET results. Suspicious foci on end-PET received biopsy confirmation whenever possible. Median follow-up was 58·9 months. Uptake on int-PET higher than liver (scores 4-5) was rated positive according to the Lugano classification, while a positive end-PET corresponded to scores 3, 4 and 5. Fifteen patients had treatment failure. Sensitivity, specificity, positive predictive value (PPV), negative predictive value and accuracy of int-PET were 46·7%, 85·2%, 43·8%, 86·7% and 77·6%, respectively. For end-PET the figures were: 80%, 93·4%, 75%, 95% and 90·8%. Eight patients with negative int-PET had treatment failure; six of them were identified as non-responders with end-PET. The 5-year progression-free survival (PFS) was 87% for patients with negative int-PET versus 56% with positive int-PET. The 5-year PFS was 96% with negative end-PET versus 23% with positive end-PET. The prognostic information from int-PET as regards PFS (log-rank test P = 0·0048) was lower than that provided by end-PET (P < 0·0001). Int-PET predicted only half of the failures. When used in clinical routine, a negative int-PET study cannot obviate the need for end-PET examination.

Evaluation of (68)Ga-DOTA-TOC PET/CT for the detection of duodenopancreatic neuroendocrine tumors in patients with MEN1.

CONTEXT: Somatostatin receptor scintigraphy with (111)In-pentetreotide (SRS) is used to detect duodenopancreatic neuroendocrine tumors (dpNETs) in multiple endocrine neoplasia type 1 (MEN1). However, SRS has limited sensitivity for this purpose. Positron emission tomography/computed tomography (PET/CT) with (68)Ga-DOTA-TOC has a higher rate of sporadic dpNETs detection than SRS but there is little data for dpNETs detection in MEN1. PURPOSE: To compare the performances of (68)Ga-DOTA-TOC PET/CT, SRS and contrast-enhanced computed tomography (CE-CT) to diagnose dpNETs in MEN1. DESIGN AND SETTING: Single-institution prospective comparative study PATIENTS AND METHODS: Nineteen consecutive MEN1 patients (aged 47 ± 13 years) underwent (68)Ga-DOTA-TOC PET/CT, SRS, and CE-CT within 2 months in random order. Blinded readings of images were performed separately by experienced physicians. Unblinded analysis of CE-CT, combined with additional magnetic resonance imaging, endoscopic-ultrasound, (18)F-2-fluoro-deoxy-D-glucose ((18)F-FDG) PET/CT or histopathology results served as reference standard for dpNETs diagnosis. RESULTS: The sensitivity of (68)Ga-DOTA-TOC PET/CT, SRS, and CE-CT was 76, 20, and 60 %, respectively (p < 0.0001). All the true-positive lesions detected by SRS were also depicted on (68)Ga-DOTA-TOC PET/CT. (68)Ga-DOTA-TOC PET/CT detected lesions of smaller size than SRS (10.7 ± 7.6 and 15.2 ± 5.9 mm, respectively, p < 0.03). False negatives of (68)Ga-DOTA-TOC PET/CT included small dpNETs (<10 mm) and (18)F-FDG PET/CT positive aggressive dpNETs. No false positives were recorded. In addition, whole-body mapping with (68)Ga-DOTA-TOC PET/CT identified extra-abdominal MEN1-related tumors including one neuroendocrine thymic carcinoma identified by the three imaging procedures, one bronchial carcinoid undetected by CE-CT and three meningiomas undetected by SRS. CONCLUSIONS: Owing to higher diagnostic performance, (68)Ga-DOTA-TOC PET/CT (or alternative (68)Ga-labeled somatostatin analogues) should replace (111)In-pentetreotide in the investigation of MEN1 patients.

18F-FDG PET for the identification of adrenocortical carcinomas among indeterminate adrenal tumors at computed tomography scanning.

BACKGROUND: 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) has been proposed for the evaluation of adrenal tumors. However, only scarce data are available to evaluate its usefulness for the identification of primary adrenal carcinomas in patients with no previous history of cancer and equivocal tumors on computed tomography (CT) scan. The objective of the present study was to evaluate the diagnostic performance of 18F-FDG-PET to predict malignancy in such patients. METHODS AND PATIENTS: This was a retrospective study carried out from 2006 to 2009 in a single university hospital center. Twenty-three consecutive patients without previous history of cancer investigated for adrenal tumors without features of benign adrenocortical adenoma on CT scan but no obvious ACC underwent 18F-FDG PET. All patients underwent adrenalectomy because of CT scan characteristics regardless of the results of 18F-FDG PET. The ratio of maxSUV adrenal tumor on maxSUV liver (adrenal/liver maxSUV ratio) during 18F-FDG PET was compared to Weiss pathological criteria. RESULTS: Seventeen patients had an adrenal adenoma, 2 had small size adrenal carcinomas (<5 cm), 1 had an angiosarcoma, and 3 had noncortical benign lesions. An adrenal/liver maxSUV ratio above 1.6 provided 100% sensitivity, 90% specificity, and 100% negative predictive value for the diagnosis of malignant tumor. CONCLUSIONS: Because of its excellent negative predictive value, 18F-FDG-PET may be of help in avoiding unnecessary surgery in patients with non-secreting equivocal tumors at CT scanning and low 18F-FGD uptake.

Systemic tuberculosis presenting as an epiglottic mass detected on F-18 FDG PET/CT.

A 32-year-old man presented with asthenia, weight loss, cough, and dysphagia following a recent stay in Morocco. Endoscopy showed a bulky mass of the epiglottis suspected of being a malignant tumor. The patient underwent jointly an F-18 FDG PET/CT and a biopsy of the tumor. Against all expectations, biopsy revealed granulomatous inflammation with epitheloid giant cells and caeseating necrosis. These findings associated with the presence of acid-fast bacilli in the sputum smears were highly suggestive of laryngeal tuberculosis, which was confirmed later after cultivation of mycobacteria. F-18 FDG PET showed diffuse pharyngolaryngeal and lung uptake with bilateral cervical and abdominal nodes, but also one thoracic vertebral uptake. Lung CT could have revealed carcinomatous dissemination, but cavitary lesions in some pulmonary segments were more evocative of tuberculosis. Moreover, cerebral MRI showed brain tuberculomas not visualized on F-18 FDG PET/CT. The patient was treated with a 5-antituberculosis drug regimen, which improved clinical symptoms with epiglottis mass regression, and lung CT image reduction, clinching the systemic tuberculosis diagnosis. A control F-18 FDG PET/CT performed 5 months later showed disappearance of the pharyngolaryngeal and node uptake, with an improvement of lung uptake without normalization, arguing for persistent disease. Unexpected pathologic findings may be present in more than 3% of neck dissections. Although this is usually indolent, with the underlying SCC remaining the main prognostic determinate, it may significantly complicate postoperative management.

Variability of Hepatic 18F-FDG Uptake at Interim PET in Patients With Hodgkin Lymphoma.

INTRODUCTION: When evaluating response of Hodgkin lymphoma (HL) to chemotherapy on interim (18)F-FDG-PET/CT, physiological liver uptake is used as reference. Hodgkin lymphoma sites with uptake greater than liver are interpreted as positive. We aimed at examining factors that might influence liver uptake as reference organ. METHODS: Fifty patients with HL who received baseline (18)F-FDG-PET/CT (PET1) and interim PET (PET2), usually after 2 cycles of adriamycin bleomycin, vinblastine, and dacarbazine chemotherapy, were included retrospectively. SUVmean normalized for body weight (SUVmean) and for lean body mass (SULmean) were obtained from regions of interest in the right lobe of the liver. RESULTS: On univariate analysis, liver SUVmean on interim PET increased with increasing body mass index (BMI) (P = 0.0453) and were higher in women (P = 0.0401). These factors remained significant on multivariate analysis (P = 0.009 and P = 0.008, respectively). No significant correlation was found with postinjection delay, blood glucose level, and age. Liver SULmean were not affected by the studied variables. Average liver SUVmean in the 50 patients were similar at baseline and interim PET. In 11 patients (22%), however, there was 30% or greater variation in liver SUVmean between PET1 and PET2. No factors explaining intrapatient variation in hepatic uptake between PET1 and PET2 were found on correlation analysis. CONCLUSION: At interim PET in patients with HL, liver SUVmean depends on BMI and sex, but not liver SULmean. Furthermore, our study, conducted with standard clinical procedure, also confirmed the high range of liver uptake values from one patient to another. Caution is required when using liver SUV as reference in patients with high BMI. Intrapatient fluctuation in liver SUVmean should also be expected.

SPECT-CT improves detection of small peritoneal fistula.

A 51-year-old woman on peritoneal dialysis for chronic renal failure underwent laparotomy for kidney transplant. One month later, painful subcutaneous edema was observed within the abdominal wall especially apparent in the standing position. A peritoneal fistula was suspected. Peritoneal scintigraphy was performed after infusion of Tc-99m sulfur colloid into the peritoneal cavity followed by SPECT/CT. Tracer uptake was observed between the peritoneal cavity and the subcutaneous space suggesting a postsurgical peritoneal fistula. On static images, the origin of the slight uptake was difficult to determine and could be due to the presence of Tc-99m in the peritoneal catheter that projects into this area. SPECT/CT improved detection of a small peritoneal fistulas.