Purpose: To determine the value of combined positron emission tomography/computed tomography (PET/CT) during induction chemotherapy (CTx) followed by chemoradiotherapy (CTx/ RTx) for non^small-cell lung cancer to predict histopathologic response in primary tumor and mediastinum and prognosis of the patient. Experimental Design: Fifty consecutive patients with locally advanced non^small-cell lung cancer received induction therapy and, if considered resectable, proceeded to surgery (37 of 50 patients). Patients had at least two repeated 18 F-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT scans either before treatment (t 0 ) or after induction CTx (t 1 ) or CTx/RTx (t 2 ).Variables from the PET/CTstudies [e.g., lesion volume and corrected maximum standardized glucose uptake values (SUV max,corr )] were correlated with histopathologic response (graded as 3, 2b, or 2a: 0%, >0-10%, or >10% residual tumor cells) and times to failure.Results: Primary tumors showed a percentage decrease in SUV max,corr during induction significantly larger in grade 2b/3 than in grade 2a responding tumors (67% versus 34% at t 1 , 73% versus 49% at t 2 ; both P < 0.005). SUV max,corr at t 2 was significantly correlated with histopathologic response in tumors smaller than the median volume (7.5 cm 3 ; r = À0.54, P = 0.02). In the mediastinal lymph nodes, SUV max,corr values at t 2 predicted an ypN 0 status with a sensitivity and specificity of 73% and 89%, respectively (SUV max,corr threshold of 4.1, r = À0.54, P = 0.0005). Freedom from extracerebral relapse was significantly better in grade 2b/3 patients (86% at16 months versus 20% in 2a responders; P = 0.003) andinpatients with a greater percentage decrease in SUV max,corr in the primary tumor at t 2 in relation to t 0 than in patients with lesser response (83% at 16 months versus 43%; P = 0.03 for cutoff points between 0.45 and 0.55). Conclusions: SUV max,corr values from two serial PET/CT scans, before and after three chemotherapy cycles or later, allow prediction of histopathologic response in the primary tumor and mediastinal lymph nodes and have prognostic value.

The aim of this study is to evaluate the clinical significance of (124)I positron emission tomography (PET) using a combined PET/CT tomograph in patients with differentiated thyroid carcinoma and to compare the PET/CT results with (131)I whole-body scintigraphy (WBS), dedicated PET and CT alone. Twelve thyroid cancer patients were referred for diagnostic workup and entered complete clinical evaluation, including histology, cytology, thyroglobulin level, ultrasonography, fluorine-18 fluorodeoxyglucose (FDG)-PET, FDG-PET/CT and CT. Lesion-based evaluation showed a lesion delectability of 56, 87 and 100% for CT, (124)I-PET, and combined (124)I-PET/CT imaging, respectively. Lesion delectability of (131)I-WBS was 83%. We conclude that (124)I-PET/CT imaging is a promising technique to improve treatment planning in thyroid cancer. It is particularly valuable in patients suffering from advanced differentiated thyroid cancer prior to radio-iodine therapy and in patients with suspected recurrence and potential metastatic disease.

Total knee arthroplasty is successful in the treatment of degenerative, arthritic or injured joints. But the most important long term complication seems to be aseptic loosening. An inflammatory process at the bone/cement or bone/prosthesis interface leads to a severe osteolysis. Although early diagnosis is very important the standard techniques often fail. [(18)F]Fluoride ion positron emission tomography (F-PET) is an appropriate tracer paired with a modern method for the evaluation of increased bone metabolism at the bone/prosthesis interface. In this preliminary study we describe for the first time the value of F-PET in the early diagnosis of aseptic loosening. We studied 14 painful knee arthoplasties. In 6 cases the definite diagnosis was determined by surgical procedure, for 8 cases a long clinical follow-up of the least 6 months after the onset of symptoms led to the diagnosis. The F-PET scans were obtained by with an ECAT EXACT HR+ scanner with and without attenuation correction in the two-and three-dimensional mode. An intermediate or high uptake along the bone/prosthesis or bone/cement interface including either the tibial stem or the half of the femoral component was suspected to be aseptic loose. The result were compared with plain radiographs. We found a sensitivity of 100%, a specificity of 56% and an accuracy of 71%. No false negative results were detected, in 4 patients one component as false positive. The sensitivity, specificity and accuracy for the plain radiograph of the same patients were 43%, 86% and 64%, respectively. In conclusion PET seems to be a promising new method in the early diagnosis of painful TKA because of its excellent spatial solution. In combination with the bone seeking tracer [(18) F]fluoride, PET allows the detection of aseptic loosening and the differentiation to the simple synovitis. Our preliminary results suggest that F-PET could be a useful tool although we examined a small group of patients.

In Germany, in at far the largest proportion of patients with autonomous thyroid nodules objectified by means of scintigraphy, TSH levels are within the normal range. Since such nodules with maximum safety can be classified as benign, a corresponding scintigraphic finding has a high priority for the patient. These current data support that it is not reasonable to restrict scintigraphy to patients with subnormal TSH values in this country.

Iodine-124 positron emission tomography (PET) is a useful 3D imaging technique for diagnosis and management of thyroid diseases. The difficulty in interpretation of the PET scans with highly selective tracers, such as iodine-124, is the lack of identifiable anatomical structures, so an accurate anatomical localization of foci presenting abnormal uptake is problematic. Consequently, a combined PET/CT scanner can resolve these difficulties by co-registering PET and CT data in a single session allowing a correlation of functional and morphologic imaging. A case is presented where iodine-124 produced by a clinical cyclotron and FDG were used to acquire images with a combined PET/CT scanner for clinical staging. On the basis of the PET/CT exams the treatment of the patient was modified.