Iterative Metallic Artifact Reduction for In-Plane Gonadal Shielding During Computed Tomographic Venography of Young Males.

OBJECTIVE: The purpose of this study was to evaluate a gonadal shield (GS) and iterative metallic artifact reduction (IMAR) during computed tomography scans, regarding the image quality and radiation dose. METHODS: A phantom was imaged with and without a GS. Prospectively enrolled, young male patients underwent lower extremity computed tomography venography (precontrast imaging without the GS and postcontrast imaging with the GS). Radiation dose was measured each time, and the GS-applied images were reconstructed by weighted filtered back projection and IMAR. RESULTS: In the phantom study, image artifacts were significantly reduced by using IMAR (P = 0.031), whereas the GS reduced the radiation dose by 61.3%. In the clinical study (n = 29), IMAR mitigated artifacts from the GS, thus 96.6% of the IMAR image sets were clinically usable. Gonadal shielding reduced the radiation dose to the testes by 69.0%. CONCLUSIONS: The GS in conjunction with IMAR significantly reduced the radiation dose to the testes while maintaining the image quality.

Optimization of Split-Bolus CT Urography: Effect of Differences in Allocation of Contrast Medium and Prolongation of Imaging Delay.

OBJECTIVE: The purpose of this study was to find the optimal allocation ratio of contrast medium (CM) in split-bolus CT urography (CTU) and to investigate the effect of increased imaging delays for synchronous nephrographic-excretory phase imaging. SUBJECTS AND METHODS: One hundred ninety-two patients were randomly assigned to one of three protocols with different allocation ratios of CM: group A, 30% of CM at first bolus and 70% of CM at second bolus; group B, 70% and 30%; or group C, 50% and 50%. Saline (250 mL) was administered after the first CM bolus. Patients were subdivided by different imaging delay times (8, 10, 12, and 14 minutes). The attenuation values of the renal cortex and medulla were measured, and the opacification and maximal caliber of each segment of the ureter were evaluated. RESULTS: Renal cortical enhancement was significantly higher in group A (mean ± SD, 145.9 ± 17.5 HU) than group B (120.6 ± 106.3 HU). No significant difference in renal parenchymal enhancement was found with increased imaging delay times. The opacification and maximal caliber of each ureter segment showed no significant difference with different allocation ratios of CM or increased imaging delay times. CONCLUSION: A split-bolus CTU protocol with a larger CM volume administered at the second injection and an 8-minute imaging delay was the optimal protocol with regard to opacification of the ureter, renal parenchymal enhancement, and shorter examination time.

Various factors contribute to graft extrusion in lateral meniscus allograft transplantation.

PURPOSE: Lateral meniscus allograft transplantation (LMAT) is a feasible surgical option for young meniscus-deficient patients. Although several studies have explored the factors that contribute to graft extrusion, they have not been fully elucidated. The aim of this study was to determine the various factors that contribute to graft extrusion. METHODS: Patients with knees that had received LMAT using a keyhole technique (n = 87 knees in 82 patients) were reviewed. The median age of these patients was 22 years (range 19-54 years), and the median postprocedural follow-up interval was 5 days (range 1-136 days). Twelve magnetic resonance imaging (MRI) measurement parameters (axial and coronal location of the bone block) that could potentially influence graft extrusion were evaluated, along with absolute graft extrusion and relative percentage of extrusion (RPE). RESULTS: A significant correlation was found between 8 of the 12 MRI measurement parameters and both the absolute extrusion and RPE (r = 0.241-0.438, p < 0.05). The absolute middle distance and depth of the bone block were independent predictors of the absolute extrusion (ß = 0.30 and 0.15, respectively; p < 0.05), and the relative middle distance and relative bone-block elevation were found to be predictors of RPE (ß = 2.29 and 1.44, respectively; p < 0.05). CONCLUSION: The rate of graft extrusions after LMAT was high in this study. Both the coronal and axial locations of the bone block were found to influence graft extrusion in LMAT. Therefore, correct positioning of the bone block, including in both the axial and coronal planes, is essential to minimize graft extrusion. Future studies need to investigate the long-term clinical outcome and longevity of extruded menisci after transplantation. LEVEL OF EVIDENCE: Therapeutic case series, Level IV.

A radiological classification system for talocalcaneal coalition based on a multi-planar imaging study using CT and MRI.

OBJECTIVE: To develop a radiological classification system for talocalcaneal coalition suitable for adults. METHODS AND MATERIALS: A retrospective review was performed on patients diagnosed with talocalcaneal coalition from July 2001 to November 2011. Based on the cartilaginous or bony nature, facet joint orientation and bony structure morphology, we classified talocalcaneal coalitions into four types: I (linear with or without posterior hooking), II (talar overgrowth), III (calcaneal overgrowth) and IV (complete osseous). RESULTS: Seventy feet (59 patients) with talocalcaneal coalition were evaluated by CT (61/70 feet) using multi-planar reformation and/or magnetic resonance imaging (43/70 feet). Type I, II, III and IV coalitions were detected in 45 (64 %), 10 (14 %), 13 (19 %), and 2 feet (3 %), respectively. Fracture fragments were observed in 16 feet (seven Type I and nine Type III coalitions) with hooked or overgrown calcanei and in one foot in the talus (Type I). Eleven patients had bilateral talocalcaneal coalitions; ten patients had coalitions of the same type and one had both Type I and Type III coalitions. Among 48 patients with unilateral involvement, the left and right feet were affected in 26 and 22 patients, respectively. CONCLUSIONS: A classification system for talocalcaneal coalition based on multi-planar imaging studies was developed. KEY POINTS: • A classification system for talocalcaneal coalition based on multi-planar imaging was developed. • The relative frequencies of different talocalcaneal coalition types were determined. • Fracture fragments were easily distinguished and frequently originated from the calcaneus. • Fracture fragments were mostly associated with Type I (linear) with posterior hooking and Type III (calcaneal overgrowth).

Comparison of arthroscopic and magnetic resonance imaging findings in osteochondral lesions of the talus.

BACKGROUND: Magnetic resonance imaging (MRI) is widely used for diagnosing osteochondral lesions in the talus. The purpose of this study was to directly compare the MRI with the arthroscopic findings. MATERIALS AND METHODS: MR images of 42 ankles were retrospectively reviewed during a period of 67 months. The osteochondral lesions were evaluated by both MRI (0, normal; 1, subchondral trabecular compression and marrow edema; 2A, subchondral cyst; 2B incomplete separation fragment; 3, unattached, nondisplaced fragment with synovial fluid surrounding it; 4, displaced fragment) and arthroscopy (A, smooth and intact, but soft and ballottable cartilage; B, rough surfaces; C, fibrillations or fissures; D, flap present or bone exposed; E, loose, undisplaced fragment; F, displaced fragment). Arthroscopic grade A was considered to be equivalent to MR grade 1, B and C to MR grade 2A, D to 2B, E to 3, and F to 4. RESULTS: Of the 44 lesions in 42 ankles, 29 lesions marked the same grade on both MRI and arthroscopy (65.9%). Nine lesions were upgraded on arthroscopy (20.5%), and six were downgraded (13.6%). MR grade 3 lesions showed the best correlation (83.3%) and MR grade 1 and 2B lesions showed the worst (50.0 and 55.6 %). Arthroscopic grade A and F showed good correlation (80 and 100%). Grade C and E showed poor (25.0%) and intermediate correlation (66.7%), respectively. CONCLUSION: The MRI grading of osteochondral lesions in the talus was useful and showed a fairly good correlation with arthroscopic classification.

Computed tomographic venography for varicose veins of the lower extremities: prospective comparison of 80-kVp and conventional 120-kVp protocols.

OBJECTIVE: To prospectively investigate the feasibility of an 80-kilovolt (peak) (kVp) protocol in computed tomographic venography for varicose veins of the lower extremities by comparison with conventional 120-kVp protocol. METHODS: Attenuation values and signal-to-noise ratio of iodine contrast medium (CM) were determined in a water phantom for 2 tube voltages (80 kVp and 120 kVp). Among 100 patients, 50 patients were scanned with 120 kVp and 150 effective milliampere second (mAs(eff)), and the other 50 patients were scanned with 80 kVp and 390 mAs(eff) after the administration of 1.7-mL/kg CM (370 mg of iodine per milliliter). The 2 groups were compared for venous attenuation, contrast-to-noise ratio, and subjective degree of venous enhancement, image noise, and overall diagnostic image quality. RESULTS: In the phantom, the attenuation value and signal-to-noise ratio value for iodine CM at 80 kVp were 63.8% and 33.0% higher, respectively, than those obtained at 120 kVp. The mean attenuation of the measured veins of the lower extremities was 148.3 Hounsfield units (HU) for the 80-kVp protocol and 94.8 HU for the 120-kVp protocol. Contrast-to-noise ratio was also significantly higher with the 80-kVp protocol. The overall diagnostic image quality of the 3-dimensional volume-rendered images was good with both protocols. The subjective score for venous enhancement was higher at the 80-kVp protocol. The mean volume computed tomography dose index of the 80-kVp (5.6 mGy) protocol was 23.3% lower than that of the 120-kVp (7.3 mGy) protocol. CONCLUSION: The use of the 80-kVp protocol improved overall venous attenuation, especially in perforating vein, and provided similarly high diagnostic image quality with a lower radiation dose when compared to the conventional 120-kVp protocol.

CT angiography of the renal arteries: comparison of lower-tube-voltage CTA with moderate-concentration iodinated contrast material and conventional CTA.

OBJECTIVE: The objective of our study was to investigate the feasibility of an 80-kVp protocol using a moderate-concentration contrast medium (CM) for CT angiography of the renal arteries by comparison with a conventional 120-kVp protocol using a high-concentration CM. SUBJECTS AND METHODS: Attenuation values and signal-to-noise ratios (SNRs) were determined in a phantom for the 120-kVp protocol with a high-concentration CM and the 80-kVp protocol with a moderate-concentration CM. In addition, 50 patients were prospectively enrolled in the study: 25 were scanned with 120 kVp and 200 effective mAs (mAs(eff)) after the administration of 110 mL of high-concentration CM (370 mg I/mL), and the other 25 were scanned with 80 kVp and 585 mAs(eff) after the administration of 110 mL of moderate-concentration CM (300 mg I/mL). Images of the two groups were compared in terms of arterial attenuation, SNR, contrast-to-noise ratio (CNR), and subjective degree of arterial enhancement and image quality. RESULTS: The mean attenuation of the main renal artery was significantly higher (p < 0.001) in the 80-kVp group who received moderate-concentration CM (mean ± SD, 370.0 ± 65.0 HU) than in the 120-kVp group who received high-concentration CM (269.9 ± 27.8 HU) without significant differences in SNR and CNR values. The 80-kVp protocol had significantly higher quality scores for arterial enhancement, sharpness of the artery, and overall diagnostic quality compared with the 120-kVp protocol. The effective dose of the 80-kVp protocol (4.5 mSv) was 8.2% lower than that of the 120-kVp protocol (4.9 mSv). CONCLUSION: The use of 80 kVp with moderate-concentration CM could improve arterial enhancement and provide superior image quality with a smaller amount of iodine and a lower radiation dose.

Cerebral computed tomography angiography using a low tube voltage (80 kVp) and a moderate concentration of iodine contrast material: a quantitative and qualitative comparison with conventional computed tomography angiography.

OBJECTIVE: To investigate the feasibility of an 80-kVp protocol using a moderate concentration contrast material (MC-CM) for cerebral computed tomography angiography by comparison with a conventional 120-kVp protocol using a high concentration contrast material (HC-CM). MATERIALS AND METHODS: Attenuation values and signal-to-noise ratios (SNRs) were determined in a head phantom for 2 tube voltages (80 and 120 kVp) and 2 different iodine concentration contrast materials (HC-CM and MC-CM). Among 90 consecutive patients, 45 patients were scanned with 120 kVp and 150 mAs(eff) after administration of 70 mL of HC-CM (370 mg iodine [mgI]/mL), whereas the other 45 patients were scanned with 80 kVp and 370 mAs(eff) after administration of 70 mL of MC-CM (300 mgI/mL). The Hounsfield units (HU) of the internal carotid artery T junction, SNR, contrast-to-noise ratio (CNR), subjective degree of arterial enhancement, image noise, sharpness of the cerebral arterial boundary, and overall diagnostic image quality were compared between the 2 groups. RESULTS: The mean attenuation of the internal carotid artery T junction, SNR, and CNR was significantly higher in the 80 kVp with MC-CM group (379.2, 33.7, and 31.1 HU, respectively) than in the 120 kVp with HC-CM group (282.2, 31.1, and 27.2 HU, respectively). The 80-kVp protocol resulted in significantly higher score in arterial enhancement, sharpness of the cerebral arteries, and overall diagnostic image quality. The effective dose of 80 kVp (0.7 mSv) was 22.2% lower than that of 120 kVp (0.9 mSv). CONCLUSIONS: The use of 80 kVp with MC-CM improved arterial enhancement, SNR, and CNR and provided superior quality images using a smaller amount of iodine and a lower radiation dose than the conventional protocol of 120 kVp with HC-CM.

Validation of self-report on smoking among university students in Korea.

OBJECTIVE: To validate the self-reported smoking status of Korean university students. METHODS: Subjects included 322 Korean university in Korea, who participated in an annual health screening. Data on smoking were collected through a self-reported questionnaire and urine test. The data were analyzed by the McNemar test. RESULTS: In the consistency test for males, the results from the questionnaire and the urine test were in agreement, but for females, there was a significant difference between the results reported by the 2 tests (P=.001). CONCLUSIONS: The findings showed that Korean female university students considerably underreported their smoking behavior.

[A comparison of stress levels of elementary students by geographical regions].

PURPOSE: The purpose of this study was to compare stress levels of elementary students according to three regional levels: a large city, a medium-sized city, and a rural area. METHODS: This was a descriptive comparative survey using a convenience sample of 1,161 5th-and 6th-grade students. The stress level was measured by a stress scale that consisted of 65 items regarding personal characteristics, family, school, and peer factors. The data were analyzed by chi2-test, t-test, ANOVA and multiple regression using the SPSS 10.0 statistical program. RESULTS: Overall, the mean stress scores reported by the participants were near the middle of a 5-point scale and the level of family-related stress was highest, followed by peer, school, and individual-related stress. Sixth-graders and female students showed higher stress levels than 5th-graders and male students, respectively. The participants reporting unsatisfaction with their lives and those living in large cities tended to have significantly higher stress levels. CONCLUSION: Grade, gender, life satisfaction, and regional levels were all significant factors associated with high stress levels among elementary students. Development of stress management programs for this specific population, especially targeting students who are female and living in large cities, is needed.