Early response to chemotherapy in hypopharyngeal cancer: assessment with (11)C-methionine PET, correlation with morphologic response, and clinical outcome.

UNLABELLED: Neoadjuvant chemotherapy in hypopharyngeal cancer globally improves survival, but some patients do not respond to chemotherapy and adjuvant therapy is delayed. Prediction of response to chemotherapy may allow physicians to optimize planned treatment. The aim of this study was to compare treatment response assessed early with (11)C-methionine PET and morphologic response assessed after treatment completion with MRI. METHODS: Thirteen patients with previously untreated squamous cell carcinoma of the hypopharynx, T3 or T4, were included. All patients received 3 courses of chemotherapy comprising cisplatin and 5-fluorouracil. (11)C-Methionine PET was performed before and after the first course of chemotherapy. PET estimation of response was expressed in relative variation of mean standardized uptake value (SUVmean), maximal standardized uptake value (SUVmax), volume of (11)C-methionine tumor uptake, and total tumor uptake. Posttreatment response was assessed with MRI, which was performed before the first course and after treatment completion, and expressed in relative variation of tumor volume. Patients were considered responders if their tumor volume was reduced by more than 50%. RESULTS: The relative decrease in all PET parameters correlated significantly with the relative decrease in MRI volume. The larger area under the receiver operating characteristic curve was obtained for SUVmean (0.883), but that area was close to the area of SUVmax (0.857). For methodologic considerations, SUVmax was more reproducible. The optimal threshold of response for SUVmax was -25%, leading to a mean of 83% (range, 36%-93%) sensitivity and 86% (range, 42%-100%) specificity. Using this threshold, survival at 2 y was improved for responders (83%), compared with nonresponders (57%), but the difference was not statistically significant. CONCLUSION: (11)C-Methionine PET provides early useful information about changes in tumor metabolism induced by chemotherapy in hypopharynx cancer. (11)C-Methionine PET measurements correlate with end-of-treatment response evaluated with MRI and may thus be helpful to physicians in treatment planning by avoiding unnecessary chemotherapy courses for nonresponding patients.

Gallium-67 scintigraphy in lymphoma: is there a benefit of image fusion with computed tomography?

The usefulness and complementarity of gallium (67Ga) scintigraphy and computed tomography (CT) in the management of patients with lymphoma have been extensively demonstrated. Owing to a lack of anatomical landmarks and physiological distribution of the tracer, precise localisation of abnormalities on 67Ga scintigraphy can be difficult. As fusion imaging techniques between single-photon emission tomography (SPET) and CT have been developed recently, we investigated whether use of CT/67Ga SPET fusion imaging could help in the interpretation of 67Ga scintigraphy. From November 1999 to May 2001, 52 consecutive fusion studies were performed in 38 patients [22 patients with Hodgkin's disease (HD) and 16 patients with non-Hodgkin's lymphoma (NHL)] as part of pre-treatment staging (n=13), treatment evaluation (n=20) or evaluation of suspected recurrence (n=19). 67Ga scintigraphy was carried out 2 and 6 days following the injection of 185-220 MBq 67Ga citrate. On day 2, 67Ga SPET and CT were performed, focussing on the chest and/or the abdomen/pelvis. Data from each imaging method were co-registered using external markers. 67Ga scintigraphy and CT were initially interpreted independently by nuclear medicine physicians and radiologists. CT/67Ga SPET fusion studies were then jointly interpreted and both practitioners indicated when fusion provided additional information in comparison with CT and 67Ga SPET alone. Image fusion was considered to be of benefit in 12/52 (23%) studies which were performed for initial staging (n=4), treatment evaluation (n=4) or evaluation of suspected recurrence (n=4). In these cases, image fusion allowed either confirmation and/or localisation of pathological gallium uptake (n=10) or detection of lesions not visible on CT scan (n=2). Fusion was relevant for discrimination between osseous lesions and lymph node involvement adjacent to bone, especially in the thoracic and lumbar spine and pelvis. In the abdomen and pelvis, fusion helped to differentiate physiological bowel elimination from abnormal uptake, and assisted in precisely locating uptake in neighbouring viscera of the left hypochondrium, including the spleen, left liver lobe, coeliac area, stomach wall and even the splenic flexure. At the thoracic level, fusion also proved useful for demonstrating clearly the relationships of abnormal foci to the pleura, hepatic dome, mediastinum, ribs or thoracic spine. Clinical management was altered by fusion imaging in one patient (chemotherapy was given instead of radiotherapy) and was potentially affected in three other patients (in that, in conjunction with other factors, the results of fusion imaging had an influence on the decision regarding use of irradiation and especially the treatment volume). In conclusion, CT/67Ga SPET fusion imaging allowed precise localisation of gallium uptake and correct attribution to the involved viscera, thereby altering the diagnosis in 20%-25% of studies in comparison with CT and 67Ga SPET analyses alone. CT/67Ga SPET fusion therefore appears valuable in facilitating the interpretation of 67Ga scintigraphy and we recommend its use in patients with lymphoma when CT and 67Ga scintigraphy are planned.