Quantitative Pulmonary Perfusion Imaging with 3-dimensional, Contrast-enhanced MR: Regional Difference in the Perfusion Parameters of Healthy Volunteers

PURPOSE: We wanted to evaluate the regional differences in such perfusion parameters as pulmonary blood flow (PBF), mean transit time (MTT) and pulmonary blood volume (PBV) in the entire lung of healthy volunteers with using three-dimensional, contrast-enhanced MR imaging (3D CEMRI). MATERIALS AND METHODS: Six healthy volunteers underwent dynamic 3D CEMRI (TR/TE 2.7/0.6 msec; flip angle 40degree; matrix 128x96; reconstructed matrix 256x192; rectangular field of view 450x315 mm; coronal 100-150mm-thickx10 slabs; temporal resolution 1.0 sec; 35 dynamic phases) For all subjects, 2 mL of Gd-DTPA mixed with 3 ml of physiologic saline was administered as a bolus at a rate of 5 mL/sec, and this was followed by 20 mL of physiologic saline flush. From the signal intensity-time curves, the PBF, MTT and PBV maps were generated using indicator dilution theories and the central volume principle on a pixel-by-pixel basis. A total of 54 round, 1-cm sized ROIs were placed in the lung in each subject (6 ROIs per slabx9 slices except for the most posterior slab). The regional differences of the measured parameters were statistically evaluated in the gravitational direction and in the upper-mid-lower direction by one-way ANOVA tests. RESULTS: The calculated PBF, MTT and PBV in the entire lung were 141.8+/-53.4 mL/100 mL/min (mean+/-SD), 5.35+/-1.38 sec, and 13.4+/-6.48 mL/100mL, respectively. In the gravitational direction, there was a significant increase in the PBF and PBV as it goes to the posterior direction (p < 0.05). No statistical difference was found in PBF or PBV between the upper, mid and lower lung zone areas. CONCLUSION: Regional difference in the various perfusion parameters of the lung in healthy volunteers can be quantitatively assessed with performing 3D CEMRI.

The Usefulness of 3D Quantitative Analysis with Using MRI for Measuring Osteonecrosis of the Femoral Head

PURPOSE: We wanted to evaluate the usefulness of MRI 3D quantitative analysis for measuring osteonecrosis of the femoral head in comparison with MRI 2D quantitative analysis and quantitative analysis of the specimen. MATERIALS AND METHODS: For 3 months at our hospital, 14 femoral head specimens with osteonecrosis were obtained after total hip arthroplasty. The patients preoperative MRIs were retrospectively reviewed for quantitative analysis of the size of the necrosis. Each necrotic fraction of the femoral head was measured by 2D quantitative analysis with using mid-coronal and mid-sagittal MRIs, and by 3D quantitative analysis with using serial continuous coronal MRIs and 3D reconstruction software. The necrotic fraction of the specimen was physically measured by the fluid displacement method. The necrotic fraction according to MRI 2D or 3D quantitative analysis was compared with that of the specimen by using Spearman's correlation test. RESULTS: On the correlative analysis, the necrotic fraction by MRI 2D quantitative analysis and quantitative analysis of the specimen showed moderate correlation (r = 0.657); on the other hand, the necrotic fraction by MRI 3D quantitative analysis and quantitative analysis of the specimen demonstrated a strong correlation (r = 0.952) (p < 0.05). CONCLUSION: MRI 3D quantitative analysis was more accurate than 2D quantitative analysis using MRI for measuring osteonecrosis of the femoral head. Therefore, it may be useful for predicting the clinical outcome and deciding the proper treatment option.

Contrast-Enhanced MR Angiography of Failing Hemodialysis Arteriovenous Fistulas and Grafts: A Preliminary Experience

PURPOSE: The purpose of this report is to evaluate the vascular stenosis for failing hemodialysis arteriovenous fistulas and grafts using contrast-enhanced MR imaging (CE-MRI) and to compare the results with digital subtraction angiography (DSA). MATERIALS AND METHODS: Nine patients (27 segmental vessels) with symptoms and signs of AVF stenosis or occlusion who presented to our medical department were recruited into this prospective comparative study. All of the patients with Brescia-Cimino arteriovenous fistula (AVF) or synthetic polytetrafluoroethylene (PTFE, Goretex(R)) loop graft underwent MRA and DSA of the fistula. MRA was performed with a 1.5-T system using VIBE sequence: TR/TE=3.5/1.5 msec, flip angle 20-25degrees, matrix 115x256, FOV 350x350, interpolated slice thickness 2.0 mm, fat suppression, scan time 13-18 sec and total time of 5 min. DSA was used as the reference standard for assessing the accuracy of MRA, and MRA was analyzed for the presence of stenosis or occlusion, a grading of stenosis, and the presence of collateral vessels. Two radiologists prospectively analyzed the MRAs by working in consensus. RESULTS: Regarding the stenotic grade, CE-MRA corresponded with the DSA in six patients (66.7%) and it overestimated the stenoses in three patients (33.3%). For the stenotic site, MRA had a sensitivity of 86.4%, a specificity of 40%, a positive predictive value of 32.1%, and a negative predictive value of 66.7%. CONCLUSION:Multiphase CE-MRA of the AVF noninvasively provided information comparable to that provided by DSA for the vascular stenosis regarding failing hemodialysis arteriovenous fistula.

Evaluation of Chondromalacia in the Knee Joint using Three Dimensional Fourier Transformation Constructive Interference in Steady State(CISS)

PURPOSE: To assess the usefulness of three-dimensional Fourier transformation constructive interference in steady state (CISS) for the evaluation of chondromalacia. MATERIALS AND METHODS: In 110 knee joints which underwent both MR imaging and arthroscopy, the findings were retrospectively reviewed. MR imaging sequences included two-dimensional dual-echo turbo spin-echo imaging along the sagittal and coronal planes, two-dimensional fast low-angle shot (FLASH) with magnetization transfer along the axial plane, and three-dimensional CISS along the sagittal plane. After the cartilage surfaces of each joint were divided into eight areas (each medial and lateral area of patellar facets, trochlear surfaces, femoral condyles, and tibial plateaux), a total of 880 areas were assessed. Using both combined two-dimensional (2-D turbo spin-echo and FLASH) and CISS imaging during different sessions, each chondromalacia case was assigned one of five grades. RESULTS: Arthroscopy revealed the presence of chondromalacia in 162 areas. This was first grade in 77 areas, second grade in 38, third grade in 21, and fourth grade in 26. The sensitivity, specificity, and accuracy of 2-D and CISS imaging were 48.1%, 93.7% and 85.3%, and 45.7%, 95.3% and 86.1%, respectively. Agreement between MR and arthroscopic staging occurred in 81.48% of 2-D imaging procedures and 82.16% of CISS procedures. If a difference of one grade was accepted, these proportions rose to 84.32% and 85.22%, respectively, though this increase was statistically insignificant. CONCLUSION: Though CISS imaging was less sensitive than 2-D imaging in the grading of chondromalacia, additional CISS imaging can help improve the accuracy of this grading.

Three-Dimensional Surface Rendering Image of Cerebral Cortical Disease

PURPOSE: To describe the abnormal gyral and sulcal patterns obtained by means of three-dimensional (3-D) surface-rendering MR imaging in patients with cerebral cortical disease. MATERIALS AND METHODS: Thirteen patients with cerebral cortical disease [M:F=9:4, aged 8 -55 (median, 26.6) years] underwent 3-D surface-rendering MR imaging. Seven had cortical dysplasia and six showed gyral atropic change, conditions which in all cases were pathologically confirmed. All were the subject of conventional brain MRI imaging studies using the MP-RAGE (magnetization-prepared rapid gradient-echo) sequence, and the resulting 3-D data sets were processed on a commercially available workstation. Abnormal gyral and suleal configurations were reviewed. RESULTS: Abnormal gyral and sulcal patterns were seen in all patients. In eight cases these involved the frontal lobe, in three the parietal lobe, and in two the sylvian fissure. In four patients with cortical dysplasia, conventional MR imaging revealed no cortical abnormality, but 3-D surface-rendering MRI indicated that the configuration and orientation of affected gyri and sulci were abnormal. In nine patients in whom an abnormal gyral pattern was revealed by conventional MRI, 3-D surface imaging confirmed the presence of a thick and enlarged gyrus, or that the configuration of affected gyri was atrophic and abnormal. CONCLUSION: In patients with cerebral cortical disease, 3-D surface-rendering MR imaging detects a high rate of abnormal gyral and sulcal patterns.

Three-Dimensional Surface Rendering Image of Cerebral Cortical Disease

PURPOSE: To describe the abnormal gyral and sulcal patterns obtained by means of three-dimensional (3-D) surface-rendering MR imaging in patients with cerebral cortical disease. MATERIALS AND METHODS: Thirteen patients with cerebral cortical disease [M:F=9:4, aged 8 -55 (median, 26.6) years] underwent 3-D surface-rendering MR imaging. Seven had cortical dysplasia and six showed gyral atropic change, conditions which in all cases were pathologically confirmed. All were the subject of conventional brain MRI imaging studies using the MP-RAGE (magnetization-prepared rapid gradient-echo) sequence, and the resulting 3-D data sets were processed on a commercially available workstation. Abnormal gyral and suleal configurations were reviewed. RESULTS: Abnormal gyral and sulcal patterns were seen in all patients. In eight cases these involved the frontal lobe, in three the parietal lobe, and in two the sylvian fissure. In four patients with cortical dysplasia, conventional MR imaging revealed no cortical abnormality, but 3-D surface-rendering MRI indicated that the configuration and orientation of affected gyri and sulci were abnormal. In nine patients in whom an abnormal gyral pattern was revealed by conventional MRI, 3-D surface imaging confirmed the presence of a thick and enlarged gyrus, or that the configuration of affected gyri was atrophic and abnormal. CONCLUSION: In patients with cerebral cortical disease, 3-D surface-rendering MR imaging detects a high rate of abnormal gyral and sulcal patterns.

Usefulness of 3D CISS Sequence in MR Imaging of Cervical Spine

PURPOSE: To assess the value of 3D CISS (constructive interference in steady state) MR sequence in imaging the cervical spine. MATERIALS AND METHODS: MR images of cervical spine were prospectively obtained with both conventional (sagittal TSE and axial 2D FLASH) and CISS sequences in 20 patients suspected of having cervical spinal diseases. MR technique was performed on a 1.5T MR machine. Axial, oblique coronal, and curved coronal images were reformatted with the 3D raw datas of CISS sequence which were obtained in cornal plane. The findings of CISS sequence were compared with those of the conventional sequence in terms of visualization of the neural foramen and nerve roots, detection and differentiation of herniated disc, conspicuity of the intramedullary lesion, contrast between the CSF and spinal cord and between the gray and white matters within the cord. RESULTS: In 17 cases including traumatic root avulsions, 3D CISS sequence demonstrated the intradural nerve roots with excellent contrast especially in coronal plane. Reformatted oblique coronal images of CISS sequence offered better visualization of entire neural foramen beyond the region of interest. CISS sequence was superior to the conventional sequence in demonstration of disease extent and correlation to the clinical symptoms in 4.5 cases of foraminal stenosis and in contrast between the CSF and spinal cord (n=15). CISS sequence was almost equal to the conventional sequence in detection of herniated disc (n=15). CISS was inferior to the conventional sequence in differentiation of herniated disc (n=7), delineation of intramedullary lesion (n=4) and in contrast between the gray and white matter within the cord in all patients. CONCLUSION: The 3D CISS sequence gives better information than the conventional sequence especially in the evaluation of the nerve roots and neural foramens but worse contrast of intramedullary lesion. It may well be used as a supplementary sequence in assessment of foraminal stenosis and nerve root injury.

The Usefulness of CT and MR Virtual Colonoscopy in the Evaluation of Experimental Polyp Models

PURPOSE: The purpose of this study was to evaluate the diagnostic accuracy of CT and MR virtual colonoscopy using an experimental model of colonic polyposis. MATERIALS AND METHODS: Eleven pig colons ranging from 15 to 20cm in length were cleansed and a total of 99 variable sized polyps ranging from 3 to 15mm in diameter were created. The polyps were divided into three groups according to size: <5mm(n=23), 5-9mm(n=44), and ?10mm(n=32) in diameter. Each specimen was scanned using spiral CT and MRI. Each CT and MR virtual colonoscopy was independently evaluated by two radiologists blinded to the location, size and numbers of polyps, but aware that polyps were present. Interobserver agreement regarding the detection rate of the polyps during the two types of virtual colonoscopy was measured and the diagnostic accuracy of CT and MR virtual colonoscopy was compared. Results: In both CT and MR virtual colonoscopy, the detection rates determined by the two radiologists coincided in all three groups(p<0.05). The detection rates of polyps less than 5mm, between 5 and 9mm, and 10mm or larger in diameter were 74%(17/23), 89%(39/44), and 100%(32/32), respectively, in CT colonoscopy, and 61%(14/23), 89%(39/44), and 100%(32/32), respectively in MR colonoscopy. In polyps 5mm or larger, the results of the two types of virtual colonscopy coincided but in those less than 5mm in diameter, the results of MR virtual colonoscopy were slightly inferior to those of CT colonoscopy. Conclusion: Both CT and MR virtual colonoscopy provide high detection rates of colonic polyps 5mm or larger in diameter and these techniques can therefore be used to diagnose colonic mass lesions.

The Usefulness of CT and MR Virtual Colonoscopy in the Evaluation of Experimental Polyp Models

PURPOSE: The purpose of this study was to evaluate the diagnostic accuracy of CT and MR virtual colonoscopy using an experimental model of colonic polyposis. MATERIALS AND METHODS: Eleven pig colons ranging from 15 to 20cm in length were cleansed and a total of 99 variable sized polyps ranging from 3 to 15mm in diameter were created. The polyps were divided into three groups according to size: <5mm(n=23), 5-9mm(n=44), and ?10mm(n=32) in diameter. Each specimen was scanned using spiral CT and MRI. Each CT and MR virtual colonoscopy was independently evaluated by two radiologists blinded to the location, size and numbers of polyps, but aware that polyps were present. Interobserver agreement regarding the detection rate of the polyps during the two types of virtual colonoscopy was measured and the diagnostic accuracy of CT and MR virtual colonoscopy was compared. Results: In both CT and MR virtual colonoscopy, the detection rates determined by the two radiologists coincided in all three groups(p<0.05). The detection rates of polyps less than 5mm, between 5 and 9mm, and 10mm or larger in diameter were 74%(17/23), 89%(39/44), and 100%(32/32), respectively, in CT colonoscopy, and 61%(14/23), 89%(39/44), and 100%(32/32), respectively in MR colonoscopy. In polyps 5mm or larger, the results of the two types of virtual colonscopy coincided but in those less than 5mm in diameter, the results of MR virtual colonoscopy were slightly inferior to those of CT colonoscopy. Conclusion: Both CT and MR virtual colonoscopy provide high detection rates of colonic polyps 5mm or larger in diameter and these techniques can therefore be used to diagnose colonic mass lesions.

3 DFT Magnetic Resonance Dacryocystography in the Evaluation of Epiphora

PURPOSE: To evaluate the feasibility of 3-dimensional Fourier transformation magnetic resonancedacryocystography (3DFT MR DCG: MR DCG) and its diagnostic efficacy in patients with epiphora. MATERIALS AND METHODS: Three normal volunteers and ten patients complaining of epiphora were studied by MR DCG using 3DFT CISSand 3DFT FLASH techniques. In normal volunteers, MR DCG was obtained by instillation of diluted Gd-DTPA solutionsof different concentrations (Gd-DTPA : saline=1:100, 1:50, 1:25) using various instillation methods. In patientswith epiphora, MR DCG was compared with conventional D C G . RESULTS: In normal volunteers, the best image wasobtained with the continuous instillation method during MR scanning. In all normal volunteers, MR DCG demonstratedthe entire course of the nasolacrimal duct (NLD). In patients with epiphora, however, there were five cases inwhich MR DCG failed to visualize the NLD, as well as five cases of occlusion and two of stenosis at the level ofthe proximal NLD. These findings corresponded with conventional DCG findings as four cases of occlusion at thelevel of the common canaliculi, one case of lacrimal sac, five cases of occlusion and two cases of stenosis at thelevel of the proximal NLD. There was no significant difference between MR DCG findings using 3DFT CISS and 3DFTFLASH MR techniques. CONCLUSION: MR DCG can detect the correct level of obstruction and differentiate betweenocclusion and stenosis of the NLD in patients with obstruction of the lacrimal drainage system. It may be a usefuldiagnostic method for investigating complicated cases in which conventional DCG is not possible due topost-surgical or traumatic obstruction.

Usefulness of CISS Technique in the MR Imaging Diagnosis of Intraocular Lesions

PURPOSE: To assess the usefulness of CISS images in the diagnosis of intraocular lesions, we compared CISSimages with 3mm and 1mm sliced spin-echo T2-weighted images. MATERIALS AND METHODS: In 14 patients with 15intraocular lesions(retinal detachment 10, choroidal melanoma, 2 ; cavernous hemangioma, 1 ; PHPV, 1 ; andretinoblastoma, 1). we used a 1.5T MR unit obtain CISS images and 3mm and 1mm sliced spin-echo T2-weighted images.All lesions were analyzed, and after dividing them into two subgroups(linear lesions, n=11 ; mass lesions, n=4),CISS and spin-echo T2-weighted images were compared for detection rate and conspicuity. RESULTS: With regard tothese two parameters, CISS images were superior to 1mm and 3mm sliced spin-echo T2-weighted images. For theassessment of linear lesions, CISS images (detection rate, 100% ; conspicuity, 2.88) were superior to both 1mm and3mm sliced spin-echo T2-weighted images. For mass lesions CISS images were superior to 3mm sliced spin-echoT2-weighted images, but for conspicuity, there was no significant difference between CISS images (2.75) and 1mmsliced spin-echo T2-weighted images(2.2). CONCLUSION: Due to their higher detection rate and greater conspicuity,CISS images were superior to spin-echo T2-weighted images for the diagnosis of intraocular lesions less than 3mmin diameter ; for the diagnosis of intraocular lesions, they might therefore be a useful adjunct to SE images.

Contructive Interference in Steady State(CISS) 3DFT MR Imaging of the Inner Ear and Adjacent Structures

PURPOSE: To assess the value of 3 dimensional fourier transformation interference in steady state magnetin resonance imaging(3 DFT CISS1 MRI) in depicting the inner ear and vascular structures. MATERIALS AND METHODS: Using 3DFT CISS axial and coronal MRI scans of both ears with 17.1 msec/8.0 msec/50 degree(TR/TE/FA) and 0.9mm in nominal thickness, we studied 68 normal ears of 34 volunteers aged between 15 and 54 years. We assessed the visualization of the membranous labyrinth, and of cranial nerves VII and VIII in the inner ear canal. We analyzed the location of the vascular loop of the anterior inferior cerebellar artery in relation to cranial nerves VII and internal auditory canal. To define the three-dimensional images of the membranous labyrinth, MIP reconstruction of axial images was carried out. RESULTS: The very high signal of the intralabyrinth fluid enabled one hundred percent of the membranous labrynth to be seen. There was a lack of contrast between soft tissue and bone such as the facial nerve canal, vestibular aqueduct and canal of the subarcuate artery. In 25% of cases, the vascular loop was recognized in the porus acusticus, and in 6% of cases, inside the internal auditory canal. CONCLUSION: 3DFT CISS MRI is useful for determining the detailed anatomy of the inner ear and the nearby vascular loop. This special MR technique can be added as a routine protocol in the study of diseases of the inner ear.