Kazuhiko Shinki

Background Fluctuation of Kidney Function Versus Contrast-Induced Nephrotoxicity

OBJECTIVE The reported incidence of contrast-induced acute kidney injury varies widely. Almost no studies have been conducted to quantify the background fluctuation of kidney function of patients receiving iodinated contrast medium. The purpose of this study was a retrospective comparison of the incidence of acute kidney injury among patients undergoing CT with low-osmolar (iohexol) or isoosmolar (iodixanol) contrast medium with the incidence among patients undergoing CT without contrast administration. MATERIALS AND METHODS Creatinine concentration and estimated glomerular filtration rate were evaluated for 11,588 patients. Rates of acute kidney injury (defined as a 0.5 mg/dL increase in serum creatinine concentration or a 25% or greater decrease in estimated glomerular filtration rate within 3 days after CT) were compared among groups and stratified according to creatinine concentration and estimated glomerular filtration rate before the imaging examination. RESULTS In all groups, the incidence of acute kidney injury increased with increasing baseline creatinine concentration. No significant difference in incidence of presumed contrast-induced kidney injury was identified between the isoosmolar contrast medium and the control groups. The incidence of acute kidney injury in the low-osmolar contrast medium cohort paralleled that of the control cohort up to a creatinine level of 1.8 mg/dL, but increases above this level were associated with a higher incidence of acute kidney injury. CONCLUSION We identified a high incidence of acute kidney injury among control subjects undergoing unenhanced CT. The incidence of creatinine elevation in this group was statistically similar to that in the isoosmolar contrast medium group for all baseline creatinine values and all stages of chronic kidney disease. These findings suggest that the additional risk of acute kidney injury accompanying administration of contrast medium (contrast-induced nephrotoxicity) may be overstated and that much of the creatinine elevation in these patients is attributable to background fluctuation, underlying disease, or treatment.

Juvenile versus Adult Osteochondritis Dissecans of the Knee: Appropriate MR Imaging Criteria for Instability

PURPOSE To retrospectively compare the sensitivity and specificity of previously described magnetic resonance (MR) imaging criteria for the detection of instability in patients with juvenile or adult osteochondritis dissecans (OCD) of the knee, with arthroscopic findings as the reference standard. MATERIALS AND METHODS Informed consent was waived by the Institutional Review Board for this HIPAA-compliant study. The study group consisted of 32 skeletally immature patients (25 boys, seven girls; mean age, 14.4 years) with 36 juvenile OCD lesions of the knee and 33 skeletally mature patients (25 men, eight women; mean age, 26.2 years) with 34 adult OCD lesions of the knee. All patients had been evaluated with MR imaging and arthroscopy. MR studies were retrospectively reviewed by two radiologists in consensus to determine the presence of previously described MR imaging criteria for OCD instability (ie, high T2 signal intensity rim, surrounding cysts, high T2 signal intensity cartilage fracture line, and fluid-filled osteochondral defect). Sensitivity and specificity of the criteria were calculated separately for juvenile and adult OCD lesions. RESULTS Separately, previously described MR imaging criteria for detection of OCD instability were 0%-88% sensitive and 21%-100% specific for juvenile OCD lesions and 27%-54% sensitive and 100% specific for adult OCD lesions. When used together, the criteria were 100% sensitive and 11% specific for instability in juvenile OCD lesions and 100% sensitive and 100% specific for instability in adult OCD lesions. CONCLUSION Previously described MR imaging criteria for OCD instability have high specificity for adult but not juvenile lesions of the knee.

Comparison of 1.5- And 3.0-T MR imaging for evaluating the articular cartilage of the knee joint

PURPOSE To retrospectively compare the diagnostic performance of 1.5- and 3.0-T magnetic resonance (MR) imaging protocols for evaluating the articular cartilage of the knee joint in symptomatic patients. MATERIALS AND METHODS This HIPAA-compliant study was performed with a waiver of informed consent from the institutional review board. The study group consisted of 200 symptomatic patients undergoing MR examination of the knee at 1.5 T (61 men, 39 women; mean age, 38.9 years) or 3.0 T (52 men, 48 women; mean age, 39.1 years), who also underwent subsequent arthroscopic knee surgery. All MR examinations consisted of multiplanar fast spin-echo sequences with similar tissue contrast at 1.5 and 3.0 T. All articular surfaces were graded at arthroscopy by using the Noyes classification system. Three musculoskeletal radiologists retrospectively and independently graded all articular surfaces seen at MR imaging by using a similar classification system. The sensitivity, specificity, and accuracy of the 1.5- and 3.0-T MR protocols for detecting cartilage lesions were determined by using arthroscopy as the reference standard. The z test was used to compare sensitivity, specificity, and accuracy values at 1.5 and 3.0 T. RESULTS For all readers combined, the respective sensitivity, specificity, and accuracy of MR imaging for detecting cartilage lesions were 69.3%, 78.0%, and 74.5% at 1.5 T (n = 241) and 70.5%, 85.9%, and 80.1% at 3.0 T (n = 226). The MR imaging protocol had significantly higher specificity and accuracy (P < .05) but not higher sensitivity (P = .73) for detecting cartilage lesions at 3.0 T than at 1.5 T. CONCLUSION A 3.0-T MR protocol has improved diagnostic performance for evaluating the articular cartilage of the knee joint in symptomatic patients when compared with a 1.5-T protocol.

Vastly Undersampled Isotropic Projection Steady-State Free Precession Imaging of the Knee: Diagnostic Performance Compared with Conventional MR

PURPOSE To compare a vastly undersampled isotropic projection steady-state free precession (VIPR-SSFP) sequence and routine magnetic resonance (MR) imaging for evaluating the cartilage, ligaments, menisci, and osseous structures of the knee in symptomatic patients. MATERIALS AND METHODS All subjects signed written informed consent prior to participation in this prospective, HIPAA-compliant, institutional review board-approved study. VIPR-SSFP was added to the routine 1.5-T MR imaging performed on 95 symptomatic patients (52 men, 43 women; average age, 41.6 years) who subsequently underwent arthroscopic knee surgery. All MR examinations were independently reviewed twice by two musculoskeletal radiologists to detect cartilage lesions, anterior and posterior cruciate ligament tears, meniscal tears, and bone marrow edema lesions, first by using routine MR and second by using VIPR-SSFP. By using arthroscopy as the reference standard, the sensitivity and specificity of both MR protocols were calculated. The z test was used to compare sensitivity and specificity values. RESULTS VIPR-SSFP had significantly higher specificity (P < .01) for helping detect cartilage lesions (92.2% for VIPR-SSFP and 88.4% for routine MR), while routine MR had significantly higher sensitivity (P = .02) and accuracy (P = .05) for helping detect lateral meniscal tears (73.2% sensitivity and 88.4% accuracy for VIPR-SSFP and 87.5% specificity and 93.2% accuracy for routine MR). There was no significant difference (P = .14 to >.99) between VIPR-SSFP and routine MR in the remaining sensitivity and specificity values. VIPR-SSFP helped detect 69.3% of bone marrow edema lesions identified at routine MR. CONCLUSION VIPR-SSFP can provide important clinical information regarding the cartilage, ligaments, menisci, and osseous structures of the knee, but is less sensitive than conventional MR imaging at helping detect lateral meniscal tears and bone marrow edema lesions.

Endovascular Abdominal Aortic Aneurysm Repair: Nonenhanced Volumetric CT for Follow-up

PURPOSE To evaluate the clinical usefulness of volumetric analysis at nonenhanced computed tomography (CT) as the sole method with which to follow up endovascular abdominal aortic aneurysm repair (EVAR) and to identify endoleaks causing more than 2% volumetric increase from the previous volume determination. MATERIALS AND METHODS The study had institutional review board approval. Images were reviewed retrospectively in a HIPAA-compliant manner for 230 CT studies in 70 patients (11 women, 59 men; mean age, 74 years) who underwent EVAR. The scannning protocol consisted of three steps: (a) contrast material-enhanced CT angiography before endovascular stent placement, (b) contrast-enhanced CT angiography 0-3 months after repair to depict immediate complications, and (c) nonenhanced CT at 3, 6, and 12 months after repair. At each follow-up visit, immediate aortic volume analysis was performed. If the interval volumetric change was 2% or less, no further imaging was performed. If the volume increased by more than 2% on the nonenhanced CT image, contrast-enhanced CT angiography was performed immediately to identify the suspected endoleak. Confidence intervals (CIs) were obtained by using bootstrapping to account for repeated measurements in the same patients. RESULTS Mean volume decrease was -3.2% (95% CI: -4.7%, -1.9%) in intervals without occurrence of a clinically relevant endoleak (n = 183). Types I and III high-pressure endoleaks (n = 10) showed a 10.0% (95% CI: 5.0%, 18.2%) interval volumetric increase. Type II low-pressure endoleaks (n = 37) showed a 5.4% (95% CI: 4.6%, 6.2%) interval volumetric increase. Endoleaks associated with minimal aortic volume increase of less than 2% did not require any intervention. This protocol reduced radiation exposure by approximately 57%-82% in an average-sized patient. CONCLUSION Serial volumetric analysis of aortic aneurysm with nonenhanced CT serves as an adequate screening test for endoleak, causing volumetric increase of more than 2% from the volume seen at the previous examination.

Comparison of standard hip MR arthrographic imaging planes and sequences for detection of arthroscopically proven labral tear.

OBJECTIVE The purpose of this study was to compare multiple imaging planes and two pulse sequences for detection of arthroscopically proven labral tears. MATERIALS AND METHODS From March 2004 through June 2007, acetabular labral tear was diagnosed at hip arthroscopy of 189 patients. Preoperative MR arthrography of the affected hip was performed on 144 patients at our institution. These MR arthrograms were retrospectively reviewed by a musculoskeletal fellow and two musculoskeletal radiologists. The sequences used were coronal T1-weighted with fat saturation, coronal T2-weighted with fat saturation, sagittal T1-weighted with fat saturation, axial oblique T1-weighted with fat saturation, sagittal oblique T1-weighted with fat saturation, and axial T1-weighted. Using consensus, the reviewers evaluated images obtained with each sequence for the presence of a tear, number of slices on which a tear was seen, and the signal intensity of the tear. RESULTS Among the 144 tears, 97.2% were identified as definitely present on images obtained with at least one of the sequences. The axial oblique sequence had the highest individual detection rate (85.0%). The detection rates for the sagittal T1-weighted (74.6%), coronal T1-weighted (67.4%), and coronal T2-weighted (63.6%) sequences were intermediate. Detection rates with the axial T1-weighted (29.9%) and sagittal oblique (18.2%) sequences were low. With the combination of three sequences (coronal T2-weighted with fat saturation, axial oblique T1-weighted with fat saturation, and sagittal T1-weighted with fat saturation), 95.8% of the 144 tears were identified as definitely present. Twenty-eight percent of tears had a signal intensity less than that of gadolinium or fluid. CONCLUSION Imaging in the axial oblique plane has the highest rate of detection of acetabular labral tears. More than 95% of tears were identified with the use of three imaging planes. Signal intensity within a tear does not have to be equal to that of gadolinium or fluid to confirm the diagnosis of labral tear.

Changing trends in serious extra-articular manifestations of rheumatoid arthritis among United State veterans over 20 years

OBJECTIVES The purpose of this study was to examine prevalence trends of serious extra-articular manifestations (EAMs) in a data set representing both hospitalized and ambulatory patients with RA. METHODS This retrospective cohort study used serial cross-sectional data to examine the prevalence of serious EAMs in patients with RA from 1985 to 2006 across the United States (US) Veterans Health Administration system. Serious EAMs included rheumatoid carditis, RA lung disease, FS and pooled EAM rates included previously reported vasculitis prevalence as queried by ICD-9 searches. Statistical analysis employed auto-regression and time series analysis using the Chow and Durbin-Watson tests to detect breakpoints and linear time-trends. RESULTS Among 3 million veterans, including >35,000 RA patients annually, we noted declining RA hospitalizations emphasizing the importance of examining both the inpatient and outpatient settings to assess EAM prevalence. Individual EAM trends varied, demonstrating linear declines in FS, increases in RA lung disease and significant breakpoint declines in carditis and pooled serious EAMs. Pooled EAM prevalence dropped around 2000, from an early linear trend peak of 10% among inpatients, to <7% among both inpatients and outpatients by 2006. CONCLUSIONS Overall, serious EAMs of RA have declined among US veterans in both the inpatient and outpatient settings, with the exception of RA lung disease likely reflecting improved detection. Breakpoints in pooled EAM prevalence appear to demonstrate consistent, true declines in severe RA extra-articular disease around 2000. Future work should explore the relationship between temporal EAM trends and specific RA therapies including adoption of biological agents.

3.0-T Evaluation of Knee Cartilage by Using Three-Dimensional IDEAL GRASS Imaging: Comparison with Fast Spin-Echo Imaging

PURPOSE To compare the diagnostic performance of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) gradient-recalled acquisition in steady-state (GRASS) imaging with a routine magnetic resonance (MR) imaging protocol for evaluating knee cartilage at 3.0 T in patients by using arthroscopy as the reference standard. MATERIALS AND METHODS This prospective Health Insurance Portability and Accountability Act-compliant study was performed with a waiver of informed consent from the institutional review board. IDEAL GRASS was added to routine 3.0-T knee MR protocol performed in 95 symptomatic patients (48 males, mean age, 34.5 years; 47 females, mean age, 35.5 years) who underwent subsequent arthroscopic surgery. Radiologists used the routine MR protocol during the first review and IDEAL GRASS during the second to grade each articular surface and to determine the presence of meniscal tears. By using arthroscopy as the reference standard, the sensitivity, specificity, and accuracy of both imaging methods for detecting cartilage lesions and meniscal tears were determined. RESULTS By using the z test to compare parameters between methods, the respective sensitivity, specificity, and accuracy for detecting all 192 cartilage lesions were 68.5%, 92.6%, and 84.5% for IDEAL GRASS and 66.1%, 92.9%, and 83.9% for the routine MR protocol. There was no significant difference (P = .34-.83) in parameters between methods for detecting cartilage lesions. The respective parameters for detecting 50 medial meniscal tears were 85.0%, 91.1%, and 87.9% for IDEAL GRASS and 94.0%, 90.0%, and 92.1% for the routine MR protocol. The parameters for detecting 31 lateral meniscal tears were 58.0%, 90.6%, and 80.0% for IDEAL GRASS and 80.1%, 91.4%, and 87.9% for the routine MR protocol. The routine MR protocol had a significantly higher sensitivity for detecting medial meniscal tears (P = .04) and lateral meniscal tears (P = .01) and significantly higher accuracy for detecting lateral meniscal tears (P = .03) than IDEAL GRASS. CONCLUSION IDEAL GRASS has similar diagnostic performance as routine MR protocol for evaluating the articular cartilage of the knee in clinical patients at 3.0 T but has significantly lower sensitivity and accuracy for detecting meniscal tears.

Comparison of the Accuracy Rates of 3-T and 1.5-T MRI of the Knee in the Diagnosis of Meniscal Tear

OBJECTIVE The purpose of this study was to compare the accuracy of 3-T MRI with that of 1.5-T MRI of the knee in the diagnosis of meniscal tear and to analyze the causes of diagnostic error. MATERIALS AND METHODS We reviewed the medical records and original MRI interpretations of 100 consecutive patients who underwent 3-T MRI of the knee and of 100 consecutive patients who underwent 1.5-T MRI of the knee to determine the accuracy of diagnoses of meniscal tear. Knee arthroscopy was the reference standard. We retrospectively reviewed all MRI diagnostic errors to determine the cause of the errors. RESULTS At arthroscopy, 109 medial and 77 lateral meniscal tears were identified in the 200 patients. With two abnormal MR images indicating a meniscal tear, the sensitivity and specificity for medial tear were 92.7% and 82.2% at 1.5-T MRI and 92.6% and 76.1% at 3-T MRI (p = 1.0, p = 0.61). The sensitivity and specificity for lateral tears were 68.4% and 95.2% at 1.5-T MRI and 69.2% and 91.8% at 3-T MRI (p = 1.0, p = 0.49). Of the false-positive diagnoses of medial meniscal tear, five of eight at 1.5 T and seven of 11 at 3 T were apparent peripheral longitudinal tears of the posterior horn. Fifteen of the 26 missed medial and lateral meniscal tears were not seen in retrospect even with knowledge of the tear type and location. CONCLUSION Allowing for sample size limitations, we found comparable accuracy of 3-T and 1.5-T MRI of the knee in the diagnosis of meniscal tear. The causes of false-positive and false-negative MRI diagnoses of meniscal tear are similar for 3-T and 1.5-T MRI.

Validation of MRI Classification System for Tibial Stress Injuries

OBJECTIVE The purpose of our study was to compare an MRI classification system for tibial stress injuries with semiquantitative MR features of injury severity and clinical outcome. MATERIALS AND METHODS Two musculoskeletal radiologists retrospectively reviewed in consensus the MR findings of 142 tibial stress injuries to quantify the degree of periosteal and bone marrow edema and grade the injuries using the Fredericson classification system (grade 1 = periosteal edema only, grade 2 = bone marrow edema visible on T2-weighted images, grade 3 = bone marrow edema visible on T1-weighted and T2-weighted images, grade 4a = multiple focal areas of intracortical signal abnormality, and grade 4b = linear areas of intracortical signal abnormality). Kruskal-Wallis tests were used to determine the relationship between the grade of stress injury and the degree of periosteal and bone marrow edema and the time to return to sports activity. RESULTS Grade 4b injuries had significantly (p < 0.002) more severe and grade 1 injuries less severe periosteal and bone marrow edema than grades 2, 3, and 4a injuries. Grade 4b injuries had significantly (p < 0.002) longer time and grade 1 injuries shorter time to return to sports activity than grades 2, 3, and 4a injuries. There was no significant difference (p = 0.06-0.79) among grades 2, 3, and 4a injuries in the degree of periosteal and bone marrow edema and the time to return to sports activity. CONCLUSION Grades 2, 3, and 4a stress injuries had similar degrees of periosteal and bone marrow edema and similar time to return to sports activity, which suggests that these three grades can be combined into a single category in an abbreviated Fredericson classification system.