Accuracy of iodine removal using dual-energy CT with or without a tin filter: an experimental phantom study.

BACKGROUND: The effects of a tin filter on virtual non-enhanced (VNE) images created by dual-energy CT have not been well evaluated. PURPOSE: To compare the accuracy of VNE images between those with and without a tin filter. MATERIAL AND METHODS: Two different types of columnar phantoms made of agarose gel were evaluated. Phantom A contained various concentrations of iodine (4.5-1590 HU at 120 kVp). Phantom B consisted of a central component (0, 10, 25, and 40 mgI/cm(3)) and a surrounding component (0, 50, 100, and 200 mgI/cm(3)) with variable iodine concentration. They were scanned by dual-source CT in conventional single-energy mode and dual-energy mode with and without a tin filter. CT values on each gel at the corresponding points were measured and the accuracy of iodine removal was evaluated. RESULTS: On VNE images, the CT number of the gel of Phantom A fell within the range between -15 and +15 HU under 626 and 881 HU at single-energy 120 kVp with and without a tin filter, respectively. With attenuation over these thresholds, iodine concentration of gels was underestimated with the tin filter but overestimated without it. For Phantom B, the mean CT numbers on VNE images in the central gel component surrounded by the gel with iodine concentrations of 0, 50, 100, and 200 mgI/cm(3) were in the range of -19-+6 HU and 21-100 HU with and without the tin filter, respectively. CONCLUSION: Both with and without a tin filter, iodine removal was accurate under a threshold of iodine concentration. Although a surrounding structure with higher attenuation decreased the accuracy, a tin filter improved the margin of error.

Incorporation of a computer-aided vessel-suppression system to detect lung nodules in CT images: effect on sensitivity and reading time in routine clinical settings.

PURPOSE: To evaluate whether a computer-aided vessel-suppression system improves lung nodule detection in routine clinical settings. MATERIALS AND METHODS: We used computer software that automatically suppresses pulmonary vessels on chest CT while preserving pulmonary nodules. Sixty-one chest CT images were included in our study. Three radiologists independently read either standard CT images alone or both computer-aided CT and standard CT images randomly to detect a pulmonary nodule ≥ 4 mm in diameter. After an interval of at least 15 days to avoid recall bias, the three radiologists interpreted the counterpart images of the same patients. The reference standard was decided by an expert panel. The primary endpoint was sensitivity. The secondary endpoint was interpretation time. RESULTS: The average sensitivity improved with computer-aided CT (72% for standard CT vs. 84% for computer-aided CT, p = 0.02). There was no difference in the false-positive rate (21% for both standard CT and computer-aided CT, p = 0.98). Although the average reading time was 9.5% longer for computer-aided plus standard CT compared with standard CT alone, the difference was not significant (p = 0.11). CONCLUSION: Vessel-suppressed CT images helped radiologists to improve the sensitivity of pulmonary nodule detection without compromising the false-positive rate.

The use of an upper-limb-artery approach and long sheaths in splanchnic angiography and interventional procedures.

BACKGROUND: The prolonged bed-rest required achieving hemostasis after splanchnic angiography and interventional procedures can be avoided if the upper limb arteries are used. In such procedures, the use of long sheaths capable of reaching the descending aorta may be advantageous. PURPOSE: To analyze the results of procedures that utilizes an upper-limb-artery approach and long sheaths. MATERIAL AND METHODS: Two hundred forty-two patients with a mean age of 64 years underwent splanchnic angiography and interventional procedures via an upper limb artery using a long sheath (85 cm, 4-French). Repeat examinations were performed on 48 patients and the total number of examinations was 296. The records of these 296 examinations were reviewed and the success rate and complications were evaluated. RESULTS: Overall, 295 of 296 (99.7%) examinations were successful, and one (0.3%) failed. Complications and side effects occurred in six cases (2.0%), a painful sheath manipulation occurred in two examinations (0.7%), and arterial occlusion (including temporary occlusion), hematoma of the puncture site, and pseudoaneurysm occurred in two (0.7%), one (0.3%), and one (0.3%) patient, respectively. CONCLUSION: The use of a long sheath capable of reaching the descending aorta enables the performance of splanchnic angiography and interventional procedures via the upper limb arteries.

CyberKnife Stereotactic Radiosurgery and Hypofractionated Stereotactic Radiotherapy As First-line Treatments for Imaging-diagnosed Intracranial Meningiomas.

Definitive radiotherapy is an important alternative treatment for meningioma patients who are inoperable or refuse surgery. We evaluated the efficacy and toxicity of CyberKnife-based stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (hSRT) as first-line treatments for intracranial meningiomas that were diagnosed using magnetic resonance imaging (MRI) and/or computed tomography (CT). Between February 2005 and September 2015, 41 patients with intracranial meningiomas were treated with CyberKnife-based SRS or hSRT. Eleven of those tumors were located in the skull base. The median tumor volume was 10.4 ml (range, 1.4-56.9 ml). The median prescribed radiation dose was 17 Gy (range, 13-20 Gy to the 61-88% isodose line) for SRS (n = 9) and 25 Gy (range, 14-38 Gy to the 44-83% isodose line) for hSRT (n = 32). The hSRT doses were delivered in 2 to 10 daily fractions. The median follow-up period was 49 months (range, 7-138). The 5-year progression-free survival rate (PFS) for all 41 patients was 86%. The 3-year PFS was 69% for the 14 patients with tumor volumes of ≥13.5 ml (30 mm in diameter) and 100% for the 27 patients with tumor volumes of <13.5 ml (P = 0.031). Grade >2 toxicities were observed in 5 patients (all of them had tumor volumes of ≥13.5 ml). SRS and hSRT are safe and effective against relatively small (<13.5 ml) meningiomas.