Basic Study for the Purpose of Developing a Quantitative 67Ga-SPECT Measurement Method.

PURPOSE: 67Ga-single photon emission computed tomography (SPECT) images vary according to the imaging time and image display methods. The calculation of an index, such as the standardized uptake value used in positron emission tomography, from 67Ga-SPECT images would enable the accurate evaluation of the region of accumulation. The purpose of this study was to elucidate the conversion formula, the lower detection limit (LDL), and recovery coefficient (RC) for quantifying the radiation concentration in the 67Ga accumulation site. METHODS: After chronologically obtaining SPECT/CT images at a radiation concentration of 1.0-442.4 kBq/mL with 27 bottles (diameter: 48 mm, 100 mL), the radiation concentration conversion formula was calculated using the successive approximation reconstruction method. The conversion coefficient was then calculated from the relationship between the count rate and the radiation concentration, and the LDL was determined. To compensate for the partial volume effect, the recovery curve was calculated using the mean SPECT count for six bottles (diameter: 9, 18, 29, 38, 48, and 94 mm). RESULTS: There was a linear relationship between the radiation concentration and the count rate with a good correlation (r=0.99). The LDL was 1.0 kBq/mL. The recovery curve reached a plateau at a diameter of at least 48 mm. CONCLUSION: The calculation of the absorbed dose index was possible using the radiation concentration conversion formula and the RC.

Three-dimensional computed tomography evaluation of semitendinosus harvest after anterior cruciate ligament reconstruction.

PURPOSE: Recent studies have shown the regeneration potential of hamstring tendons harvested for anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the morphology of the regenerated semitendinosus tendon using 3-dimensional (3-D) images of volume-rendered multidetector helical computed tomography (MD-CT). TYPE OF STUDY: Retrospective study on a convenient sample of patients. METHODS: Eight patients were selected from those with a minimum 2-year follow-up evaluation after ACL reconstruction with hamstring tendons. The harvest site of the semitendinosus tendon was evaluated using 3-D CT, in addition to magnetic resonance imaging (MRI) analysis, at an average of 37 months (range, 27 to 47 months) after surgery. RESULTS: In 5 of 8 patients, MRI evaluation indicated recurrence of the region with the same signal intensity as the native at the harvest site of the semitendinosus tendon. In these patients, the 3-D image of MD-CT visualized the stringy tendinous tissue regenerated at the harvest site originating from the semitendinosus muscle belly and running in the same pathway as the native tendon. However, the distal part attached into the medial surface of the popliteal fascia. By contrast, in the involved sides of the remaining 3 patients with no detection on MRI, the 3-D CT image showed no tendinous tissue at the harvest site. The remnants of the semitendinosus had reduced or fused into the muscle belly of the semimembranous. CONCLUSIONS: Using the 3-D CT technique, we could first depict the distinct morphology of the regenerate at the harvest site of the semitendinosus tendon. LEVEL OF EVIDENCE: Level IV, therapeutic study.

CT portography by multidetector helical CT: comparison of three rendering models.

PURPOSE: To assess the value of multidetector CT portography in visualizing varices and portosystemic collaterals in comparison with conventional portography, and to compare the visualizations obtained by three rendering models (volume rendering, VR; minimum intensity projection, MIP; and shaded surface display, SSD). METHODS: A total of 46 patients with portal hypertension were examined by CT and conventional portography for evaluation of portosystemic collaterals. CT portography was performed by multidetector CT (MD-CT) scanner with a slice thickness of 2.5 mm and table feed of 7.5 mm. Three types of CT portographic models were generated and compared with transarterial portography. RESULTS: Among the 46 patients, 48 collaterals were identified on CT transverse images, while 38 collaterals were detected on transarterial portography. Forty-four of 48 collaterals identified on CT transverse images were visualized with the MIP model, while 34 and 29 collaterals were visualized by the VR and SSD methods, respectively. The average CT value for the portal vein and varices was 198 HU with data acquisition of 50 sec after contrast material injection. CONCLUSIONS: CT portography by multidetector CT provides excellent images in the visualization of portosystemic collaterals. The images of collaterals produced by MD-CT are superior to those of transarterial portography. Among the three rendering techniques, MIP provides the best visualization of portosystemic collaterals.

Transcatheter arterial embolization therapy for a hypoplastic pelvic kidney with a single vaginal ectopic ureter to control incontinence: the usefulness of three-dimensional CT angiography using multidetector-row helical CT.

A girl with continuous urinary incontinence was successfully treated by angiographic embolization of a hypoplastic pelvic kidney with a single unilateral vaginal ectopic opening of the ureter. For this intervention, CT angiography was useful for detecting the corresponding renal artery of the hypoplastic kidney.