We have constructed a dedicated breast PET/CT scanner capable of high-resolution functional and anatomic imaging. Here, we present an initial characterization of scanner performance during patient imaging. Methods: The system consisted of a lutetium oxyorthosilicate-based dual-planar head PET camera (crystal size, 3 · 3 · 20 mm) and 768-slice cone-beam CT. The position of the PET heads (separation and height) could be adjusted for varying breast dimensions. For scanning, the patient lay prone on a specialized bed and inserted a single pendent breast through an aperture in the table top. Compression of the breast as used in mammography is not required. PET and CT systems rotate in the coronal plane underneath the patient sequentially to collect fully tomographic datasets. PET images were reconstructed with the fully 3-dimensional maximum a posteriori method, and CT images were reconstructed with the Feldkamp algorithm, then spatially registered and fused for display. Phantom scans were obtained to assess the registration accuracy between PET and CT images and the influence of PET electronics and activity on CT image quality. We imaged 4 women with mammographic findings highly suggestive of breast cancer (breast imaging reporting and data system, category 5) in an ongoing clinical trial. Patients were injected with 18 F-FDG and imaged for 12.5 min per breast. From patient data, noise-equivalent counting rates and the singles-to-trues ratio (a surrogate for the randoms fraction) were calculated. Results: The average registration error between PET and CT images was 0.18 mm. PET electronics and activity did not significantly affect CT image quality. For the patient trial, biopsy-confirmed cancers were visualized on dedicated breast PET/CT on all patient scans, including the detection of ductal carcinoma in situ in 1 case. The singles-to-trues ratio was found to be inversely correlated with breast volume in the field of view, suggesting that larger breasts trend toward increased noiseequivalent counting rates for all other things equal. Conclusion: Scanning of the uncompressed breast with dedicated breast PET/CT can accurately visualize suspected lesions in 3 dimensions. Whol e-body (WB) 18 F-FDG PET has clinical utility in breast cancer staging, restaging, and therapy response assessment. A study by Rousseau et al. (1) found that WB PET could identify tumors with pathologic response after a single course of neoadjuvant chemotherapy (sensitivity, 61%; specificity, 96%), whereas mammography had limited accuracy (sensitivity, 31%; specificity, 56%), even after 6 courses of treatment. WB PET has been shown to have a high accuracy for detecting distant metastasis. Mahner et al.(2) measured a sensitivity and specificity for metastatic disease of 87% and 83%, respectively, for WB PET, versus 43% and 98%, respectively, for combined results from chest radiography, abdominal ultrasound, and bone scintigraphy.The combination of WB PET with CT in a single platform (PET/CT) has been shown to have increased utility over either PET...

BackgroundEarly diagnosis of pulmonary hypertension (PH) can potentially improve survival and quality of life. Detecting PH using echocardiography is often insensitive in subjects with lung fibrosis or hyperinflation. Right heart catheterization (RHC) for the diagnosis of PH adds risk and expense due to its invasive nature. Pre-defined measurements utilizing computed tomography (CT) of the chest may be an alternative non-invasive method of detecting PH.MethodsThis study retrospectively reviewed 101 acutely hospitalized inpatients with heterogeneous diagnoses, who consecutively underwent CT chest and RHC during the same admission. Two separate teams, each consisting of a radiologist and pulmonologist, blinded to clinical and RHC data, individually reviewed the chest CT's.ResultsMultiple regression analyses controlling for age, sex, ascending aortic diameter, body surface area, thoracic diameter and pulmonary wedge pressure showed that a main pulmonary artery (PA) diameter ≥29 mm (odds ratio (OR) = 4.8), right descending PA diameter ≥19 mm (OR = 7.0), true right descending PA diameter ≥ 16 mm (OR = 4.1), true left descending PA diameter ≥ 21 mm (OR = 15.5), right ventricular (RV) free wall ≥ 6 mm (OR = 30.5), RV wall/left ventricular (LV) wall ratio ≥0.32 (OR = 8.8), RV/LV lumen ratio ≥1.28 (OR = 28.8), main PA/ascending aorta ratio ≥0.84 (OR = 6.0) and main PA/descending aorta ratio ≥ 1.29 (OR = 5.7) were significant predictors of PH in this population of hospitalized patients.ConclusionThis combination of easily measured CT-based metrics may, upon confirmatory studies, aid in the non-invasive detection of PH and hence in the determination of RHC candidacy in acutely hospitalized patients.

MRI may be used rather than TPBS and radiographs for evaluating acute tibial pain in athletes where avoidance of radiation exposure is desirable. Similar sensitivity and specificity may be expected from both investigations; however, in the light of abnormal TPBS and MRI findings in control and asymptomatic limbs, we recommend further studies be performed to define the extent of nonpathological TPBS and MRI changes.

Objective: Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) commonly affect the small joints of the wrist and hand. We evaluated the performance of a new, highresolution extremity positron emission tomography (PET)/CT scanner for characterizing and quantifying pathologies associated with the two arthritides in the wrist and hand joints. Methods: Patients with RA or PsA underwent fluorine-18 fludeoxyglucose ( 18 F-FDG) PET/CT wrist and hand imaging, respectively, on the high-resolution scanner. Calibrated CT images and co-registered PET images were reconstructed. PET/CT was derived for the radiocarpal and pisiform-triquetral compartments, joints with erosive changes, sites of synovitis or tenosynovitis and the nail bed and were correlated with clinical and MRI findings.

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