Young Cheol Yoon

Diagnosis of Internal Derangement of the Knee at 3.0-T MR Imaging: 3D Isotropic Intermediate-weighted versus 2D Sequences

PURPOSEnTo compare three-dimensional (3D) isotropic fast spin-echo (SE) intermediate-weighted magnetic resonance (MR) imaging with two-dimensional (2D) fast SE MR imaging-both performed at 3.0 T-for performance in the diagnosis of internal derangements of the knee.nnnMATERIALS AND METHODSnThe institutional review board approved this HIPAA-compliant study, and the requirement for informed consent was waived. The authors retrospectively reviewed 87 knee MR images obtained in 85 patients who had undergone both 3D isotropic and 2D MR examinations of the knee at 3.0 T and subsequent arthroscopic surgery. The 2D MR images included intermediate-weighted coronal and sagittal images, intermediate-weighted axial images with fat saturation, and T2-weighted sagittal images. The 3D isotropic MR images were obtained with multiplanar reformation (MPR), a fast SE intermediate-weighted sequence, and a reconstruction voxel size of 0.5 x 0.5 x 0.5 mm. Two radiologists retrospectively and independently evaluated the 2D and 3D data sets, at different sessions, for the presence of medial meniscus (MM), lateral meniscus (LM), anterior cruciate ligament (ACL), and posterior cruciate ligament (PCL) tears. These interpretations were compared with the arthroscopic surgery findings. The statistical differences between the sensitivities, specificities, and accuracies of the two methods were determined at McNemar testing, with surgical findings serving as the reference standard. Interobserver agreement was calculated by using kappa coefficients.nnnRESULTSnFor both reviewers, the sensitivity, specificity, and accuracy of both MR techniques were higher than 95% for the diagnosis of ACL and PCL tears, higher than 85% for the diagnosis of MM tears, and higher than 80% for the diagnosis of LM tears. There were no significant differences in sensitivity, specificity, or accuracy between the two methods. Interobserver agreement for evaluation of all lesions was excellent and ranged from 0.81 (LM tears evaluated with 3D and 2D sequences) to 0.93 (ACL tears evaluated with 3D and 2D sequences, PCL tears evaluated with 2D sequence, and MM tears evaluated with 3D sequence).nnnCONCLUSIONnThe performance of 3D isotropic fast SE intermediate-weighted MR imaging with MPR was not significantly different from that of 2D MR imaging in the diagnosis of cruciate ligament and meniscal tears of the knee.

Pelvic Bone Complications After Radiation Therapy of Uterine Cervical Cancer: Evaluation with MRI

OBJECTIVEnThe purpose of this study was to assess the prevalence and distribution of radiation-induced insufficiency fractures and to investigate other bony complications of the female pelvis associated with radiation therapy using MR images.nnnMATERIALS AND METHODSnTwo radiologists retrospectively evaluated pelvic MR images of 510 patients (mean age, 54.7 years) who underwent pelvic irradiation for uterine cervical cancer for the presence and location of insufficiency fractures by consensus. We calculated the cumulative prevalence of pelvic insufficiency fractures on the basis of their results. In addition, we identified other associated bony complications of the female pelvis by reviewing the MR images.nnnRESULTSnInsufficiency fractures were diagnosed in 100 patients; the 5-year cumulative prevalence was 45.2%. An insufficiency fracture was diagnosed a median of 16.9 months after radiation therapy. The fracture sites were the sacrum body and alae, medial side of the iliac bone, the roof of the acetabulum, superior rami of the pubic bone, femoral heads, and L5 vertebra. Sixty-one patients (61%) developed multiple fractures, and among them, 40 (40%) had bilateral symmetric lesions of the sacral alae. Other complications associated with the radiation therapy, as determined by evaluation of the MR images, were osteolysis and avascular necrosis of the femoral head.nnnCONCLUSIONnRadiation-induced pelvic insufficiency fractures are a frequent complication of radiation therapy for uterine cervical cancer. Osteolysis and avascular necrosis of the femoral head were also diagnosed using MRI after radiation therapy.

MRI Findings of Giant Cell Tumors of the Spine

OBJECTIVEnThe purpose of this article is to describe the MRI features of giant cell tumors of the spine in 10 patients.nnnCONCLUSIONnOne of the tumors was located in C7. The other nine tumors were located in the thoracic spine, lumbar spine, and sacrum, three in each site. The characteristic findings included an expansile mass with heterogeneous low to intermediate signal intensity on the T2-weighted images (10/10), a curvilinear area of signal void on T1- and T2-weighted images (9/10), and cystic changes within the mass (4/10). Although no imaging feature was pathognomonic, MRI was found to be valuable in identifying the tumor, revealing its extent, and defining its relationship with the intraspinal structures.

Three-dimensional Isotropic Shoulder MR Arthrography: Comparison with Two-dimensional MR Arthrography for the Diagnosis of Labral Lesions at 3.0 T

PURPOSEnTo compare the diagnostic accuracy of three-dimensional (3D) isotropic magnetic resonance (MR) arthrography with two-dimensional (2D) MR arthrography for the diagnosis of labral lesions of the shoulder performed by using a 3.0-T imager.nnnMATERIALS AND METHODSnInstitutional review board approval was given for this retrospective study and informed consent was waived. From March 2006 to January 2007, 100 patients underwent 3D isotropic and 2D MR shoulder arthrographic imaging by using a 3.0-T imager and subsequent arthroscopic surgery. The 3D isotropic sequences were performed by using fast gradient-echo imaging with fat suppression (voxel size, 0.6 x 0.6 x 0.6 mm; imaging time, 5 minutes 32 seconds) and were evaluated for the presence of superior, anterior, and posterior labral lesions by using 3D isotropic and 2D MR arthrography. The statistical differences between the sensitivity and specificity for both methods were analyzed by using the McNemar test, with arthroscopic findings regarded as reference standard.nnnRESULTSnSurgical findings confirmed 53 superior labral anterior posterior (SLAP) lesions, 17 anterior labral lesions, and five posterior labral lesions. Respective sensitivity and specificity were 85% and 96% for SLAP lesions, 100% and 98% for anterior labral lesions, and 80% and 99% for posterior labral lesions by using 2D MR arthrography and 83% and 96% for SLAP lesions, 100% and 96% for anterior labral lesions, and 80% and 99% for posterior labral lesions by using 3D isotropic MR arthrography. There was no significant difference in sensitivities and specificities of both methods; however, the power of this study was limited and larger comparison is needed.nnnCONCLUSIONnIsotropic 3D shoulder MR arthrography combined with a multiplanar reconstruction technique can help in the diagnosis of shoulder labral lesions as does 2D MR arthrography, but with shorter imaging times.

Bronchial and Nonbronchial Systemic Arteries in Patients with Hemoptysis: Depiction on MDCT Angiography

OBJECTIVEnIn this pictorial essay, we show the usefulness of MDCT angiography for visualization of the bronchial and nonbronchial systemic feeder vessels responsible for hemoptysis.nnnCONCLUSIONnBy providing thin-section transaxial, multiplanar reconstruction, and 3D images, CT angiography using MDCT allows comparable or better images than conventional angiography with respect to the depiction of bronchial or nonbronchial systemic arteries. CT angiography is particularly useful for visualizing the ectopic origin of bronchial arteries and nonbronchial systemic collateral arteries.

Comparison of indirect isotropic MR arthrography and conventional MR arthrography of labral lesions and rotator cuff tears: a prospective study.

OBJECTIVEnThe purpose of our study was to prospectively compare the diagnostic accuracy of 3D isotropic indirect MR arthrography with conventional sequences of indirect MR arthrography for the diagnosis of labral and rotator cuff lesions on a 3-T MR unit.nnnSUBJECTS AND METHODSnThirty-six consecutive patients who were scheduled for shoulder arthroscopic surgery at our institution underwent indirect MR arthrography. Both conventional sequences and an additional 3D isotropic sequence were obtained 1 day before arthroscopic surgery. Two musculoskeletal radiologists prospectively evaluated the images in consensus for the presence of superior and anterior labral lesions and subscapularis and supraspinatus-infraspinatus tendon tears using the conventional sequences and the 3D isotropic sequence. We analyzed the statistical difference between the sensitivities and specificities of both methods using arthroscopic findings as the reference standard.nnnRESULTSnSurgical findings confirmed the presence of 23 superior labral lesions, eight anterior labral lesions, 21 subscapularis tears, and 24 supraspinatus-infraspinatus tears. The sensitivity and specificity of the conventional sequences were 74% and 54% for superior labral lesions, 88% and 96% for anterior labral lesions, 67% and 85% for subscapularis tendon tears, and 96% and 75% for supraspinatus-infraspinatus tendon tears. The sensitivity and specificity of the 3D isotropic sequence were 70% and 85% for superior labral lesions, 100% and 100% for anterior labral lesions, 67% and 85% for subscapularis tendon tears, and 96% and 67% for supraspinatus-infraspinatus tendon tears. No statistically significant difference was seen in sensitivities and specificities for both methods.nnnCONCLUSIONnThree-dimensional isotropic MR arthrography sequences with multiplanar reconstruction can provide a similar capability for the diagnosis of labral and rotator cuff lesions as conventional MR arthrography sequences but in a shorter imaging time.

Knee Derangements: Comparison of Isotropic 3D Fast Spin-Echo, Isotropic 3D Balanced Fast Field-Echo, and Conventional 2D Fast Spin-Echo MR Imaging

PURPOSEnTo compare diagnostic performance, subjective image quality, and artifacts of isotropic three-dimensional (3D) intermediate-weighted (IW) fast spin-echo (SE), isotropic 3D balanced fast field-echo (FFE), and conventional two-dimensional (2D) fast SE 3.0-T MR sequences in evaluation of cartilage, ligaments, menisci, and osseous knee structures in symptomatic patients.nnnMATERIALS AND METHODSnInstitutional review board approval and waiver of informed consent were obtained for this HIPAA-compliant study. One hundred MR studies, each with three data sets (3D IW fast SE, 3D balanced FFE, 2D fast SE), were reviewed retrospectively. Two radiologists independently evaluated images for cartilaginous defects, anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial meniscus (MM), lateral meniscus (LM) tears, subchondral bone marrow signal abnormalities, subjective image quality, and image artifacts. Arthroscopic results were the reference standard. Statistical analysis was performed to calculate interobserver agreement and compare diagnostic performance of sequences.nnnRESULTSnSensitivity and specificity were greater than 85% for all lesions. For cartilaginous defects, sensitivity of 3D IW fast SE was significantly greater than that of 3D balanced FFE (95.5% vs 89.7%). Sensitivity of 3D IW fast SE and 2D fast SE for MM, LM, and ACL tears tended to be greater than that of 3D balanced FFE. IW fast SE had a higher detection rate for subchondral bone marrow signal abnormality than did 3D balanced FFE (34% vs 21%); it also had the best image quality and fewest artifacts, followed by 2D fast SE and 3D balanced FFE. Interobserver agreement was excellent for evaluation of all intraarticular structures (κ = 0.85-1) and good to excellent for detection of subchondral bone marrow signal abnormality (κ = 0.76-0.91).nnnCONCLUSIONnThe performance of IW fast SE is superior to that of balanced FFE in evaluation of cartilaginous defects, with no significant difference in performance between 2D fast SE, 3D IW fast SE, and 3D balanced FFE in evaluation of meniscal and ligament tears. Subchondral bone marrow signal abnormality is more easily seen on 3D IW fast SE images, with better subjective image quality and fewer artifacts, than on images obtained with other techniques.

Indirect MR Arthrographic Findings of Adhesive Capsulitis

OBJECTIVEnThe objective of our study was to compare the indirect MR arthrographic findings of patients with adhesive capsulitis and patients without adhesive capsulitis.nnnMATERIALS AND METHODSnIndirect MR arthrograms of 35 patients (21 women, 14 men; mean age, 50.1 years) diagnosed with adhesive capsulitis clinically were compared with indirect MR arthrograms of 45 patients (23 women, 22 men; mean age, 48.9 years) without adhesive capsulitis. Joint capsule thickness in the axillary recess and the thicknesses of the enhancing portion of the axillary recess and the rotator interval were, respectively, evaluated on coronal T2-weighted images and coronal and sagittal fat-suppressed enhanced T1-weighted images by two radiologists independently. Reliability was studied using the intraclass correlation coefficient (ICC). Receiver operating characteristic (ROC) curves were compared.nnnRESULTSnPatients with adhesive capsulitis had significantly thickened joint capsules in the axillary recess and a thickened enhancing portion in the axillary recess and in the rotator interval. The difference in the thicknesses of the enhancing portion in the axillary recess and in the rotator interval were significantly greater than the difference in joint capsule thicknesses in the axillary recess between the adhesive capsulitis group and the control group (p < 0.001). Interobserver reliability was good for all three indexes (ICC ≥ 0.80). The area under the ROC curve for the thickness of the joint capsule in the axillary recess and the thicknesses of the enhancing portion of the axillary recess and the rotator interval were 0.797, 0.861, and 0.847, respectively.nnnCONCLUSIONnAn abundance of enhancing tissue in the rotator interval and thickening and enhancement of the axillary recess are signs suggestive of adhesive capsulitis on indirect MR arthrography.

The normalized coffin- manson plot in terms of a new damage function based on grain boundary cavitation under creep- fatigue condition

A new damage function based on a model for the creep-fatigue life prediction in terms of nucleation and growth of grain boundary cavities is proposed. This damage function is a combination of the terms related to the cavitational damage in the life prediction equation and is generally applicable to the materials in which failure is controlled by the grain boundary cavitational damage. The creep-fatigue data from the present and other investigations are used to check the validity of the proposed function, and it is shown that they satisfy the reliability of damage function. Additionally, using this damage function, one may realize that all the Coffin-Manson plots at the various levels of tensile hold time and temperature under strain-controlled creep-fatigue tests can be normalized to make the master curve.

Diagnostic Efficacy in Knee MRI Comparing Conventional Technique and Multiplanar Reconstruction with One-Millimeter FSE PDW Images

Background: Magnetic resonance (MR) imaging has proved to be an excellent tool in diagnosing injuries of the cruciate ligaments and menisci. However, multiple planes and sometimes optimal oblique or double-oblique scan planes are needed due to the variability in the positioning of important structures, which means there is a lower throughput and longer scanning time. Purpose: To compare the performance of a 1-mm-thickness fast spin-echo (FSE) proton-density-weighted (PDW) MR imaging technique with multiplanar reconstruction (MPR) in diagnosing tears of the menisci and cruciate ligaments with that of conventional MR imaging. Material and Methods: Twenty-five consecutive patients underwent preoperative conventional and 1-mm-thickness FSE PDW MR imaging with subsequent knee arthroscopic surgery. Two musculoskeletal radiologists evaluated the status of the cruciate ligaments and menisci using two sets of MR images (method A: conventional images including seven sequences, taking 26u2005min; method B: 1-mm-thickness FSE PDW images with MPR, taking 7u2005min 20u2005s). The diagnostic efficacies of both methods for tears of the cruciate ligament and menisci were calculated and compared. Results: Arthroscopic surgery revealed 10 anterior cruciate ligament (ACL) tears, one posterior cruciate ligament (PCL) tear, and 26 meniscal tears. The diagnostic values of both methods were 100% for a cruciate ligament tear. The diagnostic values (sensitivity, specificity, accuracy, positive predictive value, and negative predictive value) for meniscal tears were 90%, 100%, 96%, 100%, and 94% for method A, and 95%, 100%, 98%, 100%, and 97% for method B, respectively. There were no significant differences in the diagnostic values between methods A and B. Conclusion: 1-mm-slice-thickness FSE PDW imaging with MPR showed comparable performance in diagnosing tears of the cruciate ligaments and menisci to conventional sequences but the scan time was much shorter. Therefore, this technique (method B) might improve the throughput of a 3T MR imaging system.