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Purpose: To compare the lesion conspicuity of radiofrequency ablation (RFA) zones among MR sequences according to time in the normal rabbit liver. Materials and Methods: RFA zones were created in 12 rabbit livers with a 17-gauge internally cooled electrode (1-cm active tip, 30 Watts, 3 minutes). Three rabbits were sacrificed immediately, three days, two weeks, and six weeks after the RFA procedure, respectively. Before sacrifice, T1-, T2-weighted images (WI), and gadolinium-enhanced (GE)-T1WI images were obtained. The lesion conspicuity of the RFA zone and the contrast-to-noise ratio (CNR) of the RFA zone to the liver parenchyma were analyzed and compared among the MR sequences according to time. Results: On T1WI, the RFA zones were only clearly seen on acute phase. On T2WI, the RFA zones were clearly seen on all phases except the hyperacute phase. On GE T1WI, the RFA zones were clearly seen on all phases. The CNRs of the RFA zone to the liver parenchyma of GE-T1WI (8.1-12.4) were significantly higher than the CNRs of TIWI (1.6-2.7) and T2WI (1.7-6.3) on all phases (p

Purpose: To determine the role of the use of a US-guided vacuum-assisted biopsy for the removal of sonographic evidence (excisional mammotome) for low- and high-risk benign and malignant breast lesions. Materials and Methods: We retrospectively reviewed the pathological results of 678 excisional mammotomes (611 low- and 46 high-risk benign and 21 malignant lesions). We compared the pathological results of the excisional mammotomes and the corresponding subsequent surgery of 27 high-risk benign (7/46 cases) and malignant (20/21 cases) lesions. We also reviewed the follow-up US findings of low- (306/611 cases) and high-risk benign lesions (33/39 cases). Results: Fifteen of 27 (55.6%) surgical cases revealed a residual lesion on the excisional mammotome. There was no case of upgrade pathology seen for a surgical specimen. Follow-up sonography of 306 low-risk benign lesions showed a negative finding for 231 (75.2%) cases, post-biopsy changes in 56 (17.8%) cases, and residual lesions in 19 (5.7%) cases. None of the lesion was palpable. Follow-up sonography of 33 high-risk benign lesions revealed a negative finding in 28 (85%) cases, a post-biopsy scar in 4 (12%) cases, and a local recurrence in 1 (3%) case; none of the cases showed a residual lesion. Conclusion: We suggest that an excisional mammotome can replace surgical excision for low-risk cases and may avoid the immediate surgery for high-risk benign lesions; however, surgery is crucial for a malignancy.

Purpose: We wanted to know the results and the usefulness of placing a marker clip (a surgical titanium clip) after ultrasound (US)-guided excisional mammotome biopsy for breast lesion. Materials and Methods: We have placed marker clips at the biopsy sites after performing US-guided excisional mammotome biopsies in 24 cases (mean age; 46 years, mean size of the 12.6 mm, pathologic results; benign in 19 cases, malignant in 5 cases) from Nov. 2003 to Jun. 2004. We designed the needle that we used. Twenty-five cases of follow-up sonography (at 1-month follow-up; 13 cases, at 6-months follow-up; 12 cases) were performed for 18 cases of clip placement. We retrospectively reviewed the success rate and the complications for 24 cases of clip placement, and we analyzed the visibility, conspicuity and location of the clips on 25 cases of follow-up sonography for 18 cases of clip placement. Results: The marker clip is successfully placed in all 24 cases (100%). None of the patients complained of pain or infection, except for 1 case of a large hematoma (3.5 cm). On the follow-up sonography, the titanium clip was well visualized as a short echogenic line on the interval follow-up (for the 1-month follow-up; 85%, for the 6 month follow-up; 84%) and parenchymal composition of the breast was well observed at the location of the clip (intraparenchymal; 80%, parenchyma-fat interface; 90%). The clips were easily found when there was hematoma (85%) or scar (89%). Marker clips were found within the hematoma, scar or the distorted region of tissue in all cases (100%), and there was no evidence of migration on the post-biopsy findings.

Purpose: The sensitivity encoding (SENSE) technique is increasingly being used with clinical MRI scanners. The object of this study is to compare the normative human data and image quality of the diffusion tensor imaging (DTI) with sensitivity encoding (SENSE) and standard single-shot EPI techniques. Materials and Methods: 16 normal volunteers underwent single-shot echo-planar DTI with both standard and SENSE sequences using a 1.5 T Philips Intera MR scanner (TR/TE=6755/74 or 5871/66 ms, echo train length 127 or 67, NEX=3, matrix=128128, FOV=220220 mm, slice thickness=4 mm, b value=600 , six orthogonal diffusion gradients). The diffusion tensor-encoded MR images were transferred to a PC workstation and analyzed using in-house software. The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps were calculated. The presence of artifacts (ghost susceptibility, eddy current) was graded with a two- or three-point scale. The ADC and FA values were measured in the major white matter tract and gray matter nuclei. The signal-to-noise ratio was also measured. Fisher's exact test and the Mann-Whitney test were used for the statistical analysis. Results: With SENSE, the acquisition time was reduced from 2 min 57 sec to 1 min 22 sec for DTI. Susceptibility artifacts (around the brain stem and temporal base) and eddy current artifacts were significantly reduced on the SENSE DTI as compared with those on the standard DTI (p

Purpose: To assess the usefulness of STIR (short tau inversion recovery) imaging in breast MRI (magnetic resonance imaging). Materials and Methods: We retrospectively reviewed T1- and T2-weighted (T1WI, T2WI), STIR, and dynamically enhanced images of 44 pathologically confirmed breast lesions (benign, 13; malignant, 31) in 36 patients. We selected the dynamically image which best depicted a particular lesion, and then made hard copy of the corresponding T1WI, T2WI, and STIR images. Using the dynamically enhanced image as a standard, we analysed these in terms of parenchymal pattern, lesion detectability, differentiation between benign and malignant lesions, extent, multifocality, and the ductal system. The results were statistically analyzed. Results: In 33 of 44 cases (75%), detectability was greater at STIR imaging than at T1- and T2WI, especially in fibrofatty or fatty breast (14/14 cases, p

Purpose: To evaluate the usefulness and the application of three dimensional digital rotational imaging (3D DRI) by the evaluation of fractures. Materials and Methods: Sixteen patients with clinically diagnosed or suspicious fracture were involved in this study. The lesion or suspicious sites of all 16 cases were spines (n=7), pelvis (n=3) and so on (n=6; knee, elbow, ankle, wrist and foot). In all cases, conventional radiography, multiplanar 2D (slice thickness/pitch=3 or 5 mm/1:1)and volume rendering 3D reconstructed single detector helical CT (HiSpeed Advantage, GE Medical Systems, Milwaukee, WIS) scans and 3D DRI (Integris V-5000,Philips Medical Systems, The Netherlands) with multiplanar intersection and gray scaling as postprocessing technique were performed. 3D DRI was evaluated and compared with conventional radiography, multiplanar 2D CT and volume rendering 3D CT. Results: 3D DRI provided more detail and additional information in 14 cases (88%), comparing with 2D and 3D CT scans. Two fractures were revealed only on 3D DRI other than conventional radiography and CT scans and one case was revealed on 2D CT and 3D DRI. In all cases, we could acquired more detail and additional information from 3D DRI than from 3D CT in the acquisition of 3D imaging. 3D DRI didn’t change the classification of fracture in 12 of 13 cases (92%),which revealed the fracture on the conventional radiography or CT. Conclusion: 3D DRI can diagnose and evaluate the fracture rapidly and easily with anatomical and spatial resolution by acquisition of 3D imaging with postprocessing using DRI.

Purpose: To assess the sensitivity, specificity, and diagnostic accuracy of individual contrast-enhanced helical CT findings of acute appendicitis. Materials and Methods: We retrospectively reviewed the appendiceal helical CT scans, obtained after intravenous contrast administration (abdomen; 7-mm collimation, abdominopelvic junction; 5-mm collimation), of 50 patients with surgically proven acute appendicitis and 112 with alternative diagnoses. The following parameters were analysed by three radiologists: enlarged appendix (> 6 mm in diameter), appendiceal wall thickening, appendiceal wall enhancement, no identification of the appendix, appendicolith(s), (appendiceal) intraluminal air, (appendiceal) intraluminal air extraluminal air, periappendiceal fat stranding, extraluminal fluid, phlegmon, abscess, lymphadenopathy, terminal ileal wall thickening, focal cecal apical thickening, focal colonic wall thickening, and segmental colonic wall thickening. Results: The CT findings of acute appendicitis that statistically distinguished it from alternative diagnoses were an enlarged appendix (sensitivity; 92%, specificity; 93%, diagnostic accuracy; 93%), appendiceal wall thickening (for these three parameters: 68%, 96% and 88%, respectively), periappendiceal fat stranding (90%, 79%, 82%), appendiceal wall enhancement (72%, 86%, 82%), appendicolith (16%, 100%, 74%), and focal cecal apical thickening (14%, 100%, 74%) (for each, p