Predictive value of dynamic contrast-enhanced MRI of original plaque on carotid artery in-stent restenosis / 上海交通大学学报（医学版）

Objective: To explore the value of dynamic contrast-enhanced MR imaging (DCE-MRI) of original plaque to predict carotid artery in-stent restenosis (ISR). Methods: Forty cases of the patients with carotid atherosclerosis who were to undergo the carotid artery stenting (CAS) were included in this study. All participants underwent vessel wall MR imaging (VW-MRI) and DCE-MRI within one week before CAS. Carotid digital subtraction angiography (DSA) were performed at the sixth month to reassess the stenosis of stent. The correlation between DCE-MRI and ISR was evaluated. Results: The level of Ktran in ISR group was significantly higher than that in non-ISR group (P=0.000), and so was the vP (P=0.037). Ktrans could independently predict ISR (OR=1.43, 95%CI 1.17-1.56, P=0.012), and the cut-off value of Ktrans was 0.09 min-1 (sensitivity=100%, specificity=87.5%). Conclusion: Intraplaque inflammation may lead to excessive intimal hyperplasia after ISR. Ktrans could be a risk predictor of ISR with high sensitivity and specificity. DCE-MRI could be an effective tool to predict ISR.

Preoperative Estimation of Future Remnant Liver Function Following Portal Vein Embolization Using Relative Enhancement on Gadoxetic Acid Disodium-Enhanced Magnetic Resonance Imaging

OBJECTIVE: To retrospectively evaluate relative enhancement (RE) in the hepatobiliary phase of gadoxetic acid disodium-enhanced magnetic resonance (MR) imaging as a preoperative estimation of future remnant liver (FRL) function in a patients who underwent portal vein embolization (PVE). MATERIALS AND METHODS: In 53 patients, the correlation between the indocyanine green clearance (ICG-K) and RE imaging was analyzed before hepatectomy (first analysis). Twenty-three of the 53 patients underwent PVE followed by a repeat RE imaging and ICG test before an extended hepatectomy and their results were further analyzed (second analysis). Whole liver function and FRL function were calculated on the MR imaging as follows: RE x total liver volume (RE Index) and FRL-RE x FRL volume (Rem RE Index), respectively. Regarding clinical outcome, posthepatectomy liver failure (PHLF) was evaluated in patients undergoing PVE. RESULTS: Indocyanine green clearance correlated with the RE Index (r = 0.365, p = 0.007), and ICG-K of FRL (ICG-Krem) strongly correlated with the Rem RE Index (r = 0.738, p < 0.001) in the first analysis. Both the ICG-Krem and the Rem RE Index were significantly correlated after PVE (r = 0.508, p = 0.013) at the second analysis. The rate of improvement of the Rem RE Index from before PVE to after PVE was significantly higher than that of ICG-Krem (p = 0.014). Patients with PHLF had a significantly lower Rem RE Index than patients without PHLF (p = 0.023). CONCLUSION: Relative enhancement imaging can be used to estimate FRL function after PVE.

Multiphase Contrast-Enhanced Magnetic Resonance Imaging Features of Bacillus Calmette-Guerin-Induced Granulomatous Prostatitis in Five Patients

OBJECTIVE: To evaluate the multiphase contrast-enhanced magnetic resonance (MR) imaging features of Bacillus Calmette-Guerin (BCG)-induced granulomatous prostatitis (GP). MATERIALS AND METHODS: Magnetic resonance images obtained from five patients with histopathologically proven BCG-induced GP were retrospectively analyzed for tumor location, size, signal intensity on T2-weighted images (T2WI) and diffusion-weighted images (DWI), apparent diffusion coefficient (ADC) value, and appearance on gadolinium-enhanced multiphase images. MR imaging findings were compared with histopathological findings. RESULTS: Bacillus Calmette-Guerin-induced GP (size range, 9-40 mm; mean, 21.2 mm) were identified in the peripheral zone in all patients. The T2WI showed lower signal intensity compared with the normal peripheral zone. The DWIs demonstrated high signal intensity and low ADC values (range, 0.44-0.68 x 10(-3) mm2/sec; mean, 0.56 x 10(-3) mm2/sec), which corresponded to GP. Gadolinium-enhanced multiphase MR imaging performed in five patients showed early and prolonged ring enhancement in all cases of GP. Granulomatous tissues with central caseation necrosis were identified histologically, which corresponded to ring enhancement and a central low intensity area on gadolinium-enhanced MR imaging. The findings on T2WI, DWI, and gadolinium-enhanced images became gradually obscured with time. CONCLUSION: Bacillus Calmette-Guerin-induced GP demonstrates early and prolonged ring enhancement on gadolinium-enhanced MR imaging which might be a key finding to differentiate it from prostate cancer.

Subtraction MR Venography Acquired from Time-Resolved Contrast-Enhanced MR Angiography: Comparison with Phase-Contrast MR Venography and Single-Phase Contrast-Enhanced MR Venography

OBJECTIVE: To evaluate the image characteristics of subtraction magnetic resonance venography (SMRV) from time-resolved contrast-enhanced MR angiography (TRMRA) compared with phase-contrast MR venography (PCMRV) and single-phase contrast-enhanced MR venography (CEMRV). MATERIALS AND METHODS: Twenty-one patients who underwent brain MR venography (MRV) using standard protocols (PCMRV, CEMRV, and TRMRA) were included. SMRV was made by subtracting the arterial phase data from the venous phase data in TRMRA. Co-registration and subtraction of the two volume data was done using commercially available software. Image quality and the degree of arterial contamination of the three MRVs were compared. In the three MRVs, 19 pre-defined venous structures (14 dural sinuses and 5 cerebral veins) were evaluated. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the three MRVs were also compared. RESULTS: Single-phase contrast-enhanced MR venography showed better image quality (median score 4 in both reviewers) than did the other two MRVs (p < 0.001), whereas SMRV (median score 3 in both reviewers) and PCMRV (median score 3 in both reviewers) had similar image quality (p ≥ 0.951). SMRV (median score 0 in both reviewers) suppressed arterial signal better than did the other MRVs (median score 1 in CEMRV, median score 2 in PCMRV, both reviewers) (p < 0.001). The dural sinus score of SMRV (median and interquartile range [IQR] 48, 43-50 for reviewer 1, 47, 43-49 for reviewer 2) was significantly higher than for PCMRV (median and IQR 31, 25-34 for reviewer 1, 30, 23-32 for reviewer 2) (p < 0.01) and did not differ from that of CEMRV (median and IQR 50, 47-52 for reviewer 1, 49, 45-51 for reviewer 2) (p = 0.146 in reviewer 1 and 0.123 in reviewer 2). The SNR and CNR of SMRV (median and IQR 104.5, 83.1-121.2 and 104.1, 74.9-120.5, respectively) were between those of CEMRV (median and IQR 150.3, 111-182.6 and 148.4, 108-178.2) and PCMRV (median and IQR 59.4, 49.2-74.9 and 53.6, 43.8-69.2). CONCLUSION: Subtraction magnetic resonance venography is a promising MRV method, with acceptable image quality and good arterial suppression.

Multi-time DCE-MRI and pathological characteristics of rabbit model bearing liver VX2 tumor / 吉林大学学报(医学版)

Objective To observe the growth characteristics and multi-time dynamic contrast-enhanced MR(DCE-MR)findings of rabbit VX2 liver tumor on MR imaging, and to provide a reliable basis for the values of MR in assessment of non-surgical treatment effect of rabbit VX2 liver tumor.Methods 10 rabbit VX2 liver tumor models were established by liver tissue embedding through laparotomy under direct vision and DCE-MRI scaning was performed at the 2nd,3rd,4th and 5th week after establishment.The tumor volume (V)and tumor growth rate (TGR)were calculated at different time points and the signal characteristics were analyzed on MR imaging;then all the rabbits were excuted and HE staining were performed to observe the cancer cells in different places with microscope.Results The TGR at the 3rd week after establishment (404.16%±114.64%)was significantly higher than that at the 4th week (223.49%±65.90%)(t=3.417,P<0.05).The tumors with well-boundary were rim-like enhanced significantly and the central parts were not enhanced on DCE-MR imaging,and the parts between the edge and centre of tumors were heterogeneously mild enhanced. The HE staining results showed that 6 cases of tumor were squamous cell carcinoma and the cells were distributed densely in the edge,the cancer cells and necrosis were distributed equally in the parts between the edge and centre of tumors and the centre of tumors were necrosis parts.Conclusion The rabbit VX2 liver tumor grows rapidly at the 3rd week after establishment, and its histological features can be better reflected by DCE-MRI.

Diagnostic value and clinical significance of 3D-CE-MRA in infantile superficial hemangioma / 实用放射学杂志

Objective To investigate the diagnostic value and clinical significance of the three-dimensional contrast-enhanced MR angiography (3D-CE-MRA)in the infantile superficial hemangioma.Methods Forty-four children with superficial hemangioma un-derwent conventional and dynamic contrast-enhanced MRI.MRI scanning was started at the time of inj ection,and four dynamic pha-ses of images were acquired continually.Maximum intensity proj ection (MIP)images were reconstructed to show the blood vessels of the lesions in multiple phases.Results Forty-nine infantile superficial hemangiomas were detected by MRI,including a single le-sion in 41 patients and multiple ones in 3.3D-CE-MRA showed 37 lesions in 32 patients,and other 12 lesions were not found in 12 patients.Conclusion The conventional and dynamic contrast-enhanced MRI can reflect the location,number and the range of the su-perficial hemangioma,and show the relationship between the lesion and the surrounding tissues.3D-CE-MRA directly shows the blood supply of the tumors.

Rat Model of Hindlimb Ischemia Induced via Embolization with Polyvinyl Alcohol and N-Butyl Cyanoacrylate

OBJECTIVE: To investigate the feasibility of a rat model on hindlimb ischemia induced by embolization from the administration of polyvinyl alcohol (PVA) particles or N-butyl cyanoacrylate (NBCA). MATERIALS AND METHODS: Unilateral hindlimb ischemia was induced by embolization with NBCA (n = 4), PVA (n = 4) or surgical excision (n = 4) in a total of 12 Sprague-Dawley rats. On days 0, 7 and 14, the time-of-flight magnetic resonance angiography (TOF-MRA) and enhanced MRI were obtained as scheduled by using a 3T-MR scanner. The clinical ischemic index, volume change and degree of muscle necrosis observed on the enhanced MRI in the ischemic hindlimb were being compared among three groups using the analysis of variance. Vascular patency on TOF-MRA was evaluated and correlated with angiographic findings when using an inter-rater agreement test. RESULTS: There was a technical success rate of 100% for both the embolization and surgery groups. The clinical ischemic index did not significantly differ. On day 7, the ratios of the muscular infarctions were 0.436, 0.173 and 0 at thigh levels and 0.503, 0.337 and 0 at calf levels for the NBCA, PVA and surgery groups, respectively. In addition, the embolization group presented increased volume and then decreased volume on days 7 and 14, respectively. The surgery group presented a gradual volume decrease. Good correlation was shown between the TOF-MRA and angiographic findings (kappa value of 0.795). CONCLUSION: The examined hindlimb ischemia model using embolization with NBCA and PVA particles in rats is a feasible model for further research, and muscle necrosis was evident as compared with the surgical model.

Dynamic Contrast-Enhanced MRI for Monitoring Antiangiogenic Treatment: Determination of Accurate and Reliable Perfusion Parameters in a Longitudinal Study of a Mouse Xenograft Model

OBJECTIVE: To determine the reliable perfusion parameters in dynamic contrast-enhanced MRI (DCE-MRI) for the monitoring antiangiogenic treatment in mice. MATERIALS AND METHODS: Mice, with U-118 MG tumor, were treated with either saline (n = 3) or antiangiogenic agent (sunitinib, n = 8). Before (day 0) and after (days 2, 8, 15, 25) treatment, DCE examinations using correlations of perfusion parameters (Kep, Kel, and AH from two compartment model; time to peak, initial slope and % enhancement from time-intensity curve analysis) were evaluated. RESULTS: Tumor growth rate was found to be 129% +/- 28 in control group, -33% +/- 11 in four mice with sunitinib-treatment (tumor regression) and 47% +/- 15 in four with sunitinib-treatment (growth retardation). Kep (r = 0.80) and initial slope (r = 0.84) showed strong positive correlation to the initial tumor volume (p < 0.05). In control mice, tumor regression group and growth retardation group animals, Kep (r : 0.75, 0.78, 0.81, 0.69) and initial slope (r : 0.79, 0.65, 0.67, 0.84) showed significant correlation with tumor volume (p < 0.01). In four mice with tumor re-growth, Kep and initial slope increased 20% or greater at earlier (n = 2) than or same periods (n = 2) to when the tumor started to re-grow with 20% or greater growth rate. CONCLUSION: Kep and initial slope may a reliable parameters for monitoring the response of antiangiogenic treatment.

Contrast Enhanced Cerebral MR Venography: Comparison between Arterial and Venous Triggering Methods

PURPOSE: To compare the arterial and venous detection sites of triggering methods in contrast-enhanced-MR-venography (CE-MRV) for the evaluation of intracranial venous system. MATERIALS AND METHODS: 41 healthy patients underwent CE-MRV with autotriggering at either the cavernous segment of internal carotid artery with an inserted time-delay of 6 seconds (n = 20) or the superior sagittal sinus without any time-delay (n = 21). 0.1 mmol/kg gadolinium-based contrast material (Magnevist(R), Schering, Germany) was intravenously injected by hand injection. A sagittal fast-spoiled-gradient-echo-sequence ranging from one ear to the other was performed (TR/TE5.2/1.5, Matrix 310x310, 124 sections in the 15-cm-thick volume). 17 predefined venous structures were evaluated on all venograms by two neuroradiologists and defined as completely visible, partially visible, or none visible. RESULTS: The rate of completely visible structures were 272 out of 323 (84%) in the arterial triggering CE-MRV and 310 out of 340 (91%) in the venous triggering CE-MRV. The venous triggering CE-MRV demonstrated an overall superior visualization of the cerebral veins than the arterial triggering CE-MRV (Fisher exact test, p < 0.006). CONCLUSION: CE-MRV using venous autotriggering method provides higher-quality images of the intracranial venous structures compared to that of arterial.

High Resolution Time Resolved Contrast Enhanced MR Angiography Using k-t FOCUSS

PURPOSE: Recently, the Recon Challenge at the 2009 ISMRM workshop on Data Sampling and Image Reconstruction at Sedona, Arizona was held to evaluate feasibility of highly accelerated acquisition of time resolved contrast enhanced MR angiography. This paper provides the step-by-step description of the winning results of k-t FOCUSS in this competition. MATERIALS AND METHODS: In previous works, we proved that k-t FOCUSS algorithm successfully solves the compressed sensing problem even for less sparse cardiac cine applications. Therefore, using k-t FOCUSS, very accurate time resolved contrast enhanced MR angiography can be reconstructed. Accelerated radial trajectory data were synthetized from X-ray cerebral angiography images and provided by the organizing committee, and radiologists double blindly evaluated each reconstruction result with respect to the ground-truth data. RESULTS: The reconstructed results at various acceleration factors demonstrate that each components of compressed sensing, such as sparsifying transform and incoherent sampling patterns, etc can have profound effects on the final reconstruction results. CONCLUSION: From reconstructed results, we see that the compressed sensing dynamic MR imaging algorithm, k-t FOCUSS enables high resolution time resolved contrast enhanced MR angiography.

High Resolution Time Resolved Contrast Enhanced MR Angiography Using k-t FOCUSS

PURPOSE: Recently, the Recon Challenge at the 2009 ISMRM workshop on Data Sampling and Image Reconstruction at Sedona, Arizona was held to evaluate feasibility of highly accelerated acquisition of time resolved contrast enhanced MR angiography. This paper provides the step-by-step description of the winning results of k-t FOCUSS in this competition. MATERIALS AND METHODS: In previous works, we proved that k-t FOCUSS algorithm successfully solves the compressed sensing problem even for less sparse cardiac cine applications. Therefore, using k-t FOCUSS, very accurate time resolved contrast enhanced MR angiography can be reconstructed. Accelerated radial trajectory data were synthetized from X-ray cerebral angiography images and provided by the organizing committee, and radiologists double blindly evaluated each reconstruction result with respect to the ground-truth data. RESULTS: The reconstructed results at various acceleration factors demonstrate that each components of compressed sensing, such as sparsifying transform and incoherent sampling patterns, etc can have profound effects on the final reconstruction results. CONCLUSION: From reconstructed results, we see that the compressed sensing dynamic MR imaging algorithm, k-t FOCUSS enables high resolution time resolved contrast enhanced MR angiography.

Assessment of Carotid Geometry by Using the Contrast-enhanced MR Angiography

PURPOSE: To evaluate the geometry of carotid artery by assessing the images of contrast-enhanced MR angiography (CE-MRA) and interrelationships between the geometry of carotid artery and clinical factors. MATERIALS AND METHODS: 216 consecutive patients who performed supraaortic CE-MRA with fast spoiled gradient-echo imaging were included. Their medical records were reviewed for variable information including risk factors predictive of generalized atherosclerotic disease (age, hypertension (HTN), diabetes mellitus, hyperlipidema, and smoking), sex, body weight, height, and body mass index (BMI). We reviewed the CE-MRA with carotid origin (3 types), carotid artery tortuosity, angle of internal carotid artery bifurcation, the type of aortic arch branching, and the presence of the coiling of carotid artery. RESULTS: Multinomial logistic regression analysis showed that significantly contributed clinical backgrounds for carotid origin were the age and the BMI. With an increase of age at 1, the probability that the type of carotid origin become from type 1 to type 2 was 0.9 times (p=0.004) in right carotid artery (RCA), 0.9 times (p=0.031) in left carotid artery (LCA), 0.9 times that are likely to be type3 from type 2 (p<0.001) in RCA and 0.9 times in LCA (p=0.009). Increase in BMI at 1 increased odds of becoming type 2 as 1.1 times (p=0.067) in RCA, 1.1 times (p=0.009) in LCA and increased chance of becoming type 3 as 1.2 times (p=0.001) in RCA, 1.2 times (p=0.003) in LCA. Mean value of right and left carotid tortuosity were 240.9+/-69.0degrees and 154.4+/-55.0degrees, respectively. CONCLUSION: The BMI, age, sex and presence of HTN affects the geometry of carotid arteries, the site of origin and tortuosity of carotid artery specifically.

Assessment of Carotid Geometry by Using the Contrast-enhanced MR Angiography

PURPOSE: To evaluate the geometry of carotid artery by assessing the images of contrast-enhanced MR angiography (CE-MRA) and interrelationships between the geometry of carotid artery and clinical factors. MATERIALS AND METHODS: 216 consecutive patients who performed supraaortic CE-MRA with fast spoiled gradient-echo imaging were included. Their medical records were reviewed for variable information including risk factors predictive of generalized atherosclerotic disease (age, hypertension (HTN), diabetes mellitus, hyperlipidema, and smoking), sex, body weight, height, and body mass index (BMI). We reviewed the CE-MRA with carotid origin (3 types), carotid artery tortuosity, angle of internal carotid artery bifurcation, the type of aortic arch branching, and the presence of the coiling of carotid artery. RESULTS: Multinomial logistic regression analysis showed that significantly contributed clinical backgrounds for carotid origin were the age and the BMI. With an increase of age at 1, the probability that the type of carotid origin become from type 1 to type 2 was 0.9 times (p=0.004) in right carotid artery (RCA), 0.9 times (p=0.031) in left carotid artery (LCA), 0.9 times that are likely to be type3 from type 2 (p<0.001) in RCA and 0.9 times in LCA (p=0.009). Increase in BMI at 1 increased odds of becoming type 2 as 1.1 times (p=0.067) in RCA, 1.1 times (p=0.009) in LCA and increased chance of becoming type 3 as 1.2 times (p=0.001) in RCA, 1.2 times (p=0.003) in LCA. Mean value of right and left carotid tortuosity were 240.9+/-69.0degrees and 154.4+/-55.0degrees, respectively. CONCLUSION: The BMI, age, sex and presence of HTN affects the geometry of carotid arteries, the site of origin and tortuosity of carotid artery specifically.

Contrast-Enhanced Magnetic Resonance Angiography for Evaluation of the Steno-occlusive Disease of the Supraaortic Arteries: Comparison with Computed Tomography Angiography and Digital Subtraction Angiography

PURPOSE: To intra-individually compare diagnostic accuracy of high-resolution contrast-enhanced magnetic resonance angiography (CE-MRA) with computed tomography angiography (CTA) and digital subtraction angiography (DSA) for the assessment of supraaortic steno-occlusive disease. MATERIALS AND METHODS: Twenty-eight patients (20 men, 8 women, 53-79 years of age) underwent supraaortic CE-MRA, CTA and DSA. CE-MRA was performed on two 1.5T MR scanners (voxel dimension: 0.66x0.66x1.1 or 1.2 mm3), and CTA on 64-slice CT scanners (voxel dimension: 0.42x0.42x0.63 mm3). All the three examinations were completed within 40 days (median 19 days; range 1-40 days). Retrospective evaluation and measurement of diameter of 6 extracranial and 9 intracranial arterial segments was done by 2 experienced radiologists. RESULTS: A total of 420 arterial segments were examined by CE-MRA, CTA and DSA. On DSA, 34 stenoocclusive lesions were noted at extracranial (n=19) and intracranial (n=15) vessels. For extracranial stenosis greater than 70%, sensitivity, specificity, positive predictive value (PPV) and negative predictive values (NPV) were 94.7%, 98.7%, 90.0% and 99.3% on CE-MRA, and 94.7%, 99.3%, 94.7% and 99.3% on CTA. For intracranial stenosis greater than 50%, sensitivity, specificity, PPV and NPV were 93.3%, 98.3%, 77.8%and 99.6% on CE-MRA, and 86.7%, 97.9%, 72.2% and 99.1% on CTA, with DSA as the standard of reference. CONCLUSION: Supraaortic CE-MRA is as reliable as CTA in depicting the arterial stenosis, and is effective in screening of significant stenosis of both extracranial and intracranial arterial stenosis.

Multidisciplinary Functional MR Imaging for Prostate Cancer

Various functional magnetic resonance (MR) imaging techniques are used for evaluating prostate cancer including diffusion-weighted imaging, dynamic contrast-enhanced MR imaging, and MR spectroscopy. These techniques provide unique information that is helpful to differentiate prostate cancer from non-cancerous tissue and have been proven to improve the diagnostic performance of MRI not only for cancer detection, but also for staging, post-treatment monitoring, and guiding prostate biopsies. However, each functional MR imaging technique also has inherent challenges. Therefore, in order to make accurate diagnoses, it is important to comprehensively understand their advantages and limitations, histologic background related with image findings, and their clinical relevance for evaluating prostate cancer. This article will review the basic principles and clinical significance of functional MR imaging for evaluating prostate cancer.

Preoperative diagnosis for space occupying lesion of the liver / 中华普通外科杂志

Objective To study the imaging characters and pathological diagnosis for space occupying lesions of the liver with atypical clinical and laboratory features.Methods We retrospectively analyzed the clinical data and treatment of 40 patients with space occupying lesions of the liver in which preoperative correct diagnosis was difficult,the imageological appearances and the final pathological diagnosis of these 40 space occupying lesions were compared,the specificity of B-ultrasonotomography、dynamic contrast-enhanced CT and MR scanning in identifying lesions was evaluated.Results All lesions were surgically resected.On pathology there were 22 hepatocellular carcinomas,7 macroregenerative nodules,2 focal nodular hyperplasias,2 cholangiocellular carcinomas,2 hemangiomas,2 regenerative nodules and 1 hepatocellular adenoma,1 hepatic peliosis,1 antixenic nodule.The specificity of the Bultrasonotomography for all lesions was only 20%;dynamic contrast-enhanced CT has low specificity in differential diagnosis of liver carcinoma and macroregenerative nodule and the overall specificity was 42.5%;dynamic contrast-enhanced MR scanning has excellent capability in differential diagnosing of all lesions and its specificity was 92.5%.Conclusion The preoperative diagnosis for some space occupying lesions of the liver is difficult,the differential diagnosis of these lesions should be emphasized,the dynamic contrastenhanced MR scanning for space occupying lesions of the liver has high specificity.

Preoperative Gadolinium-enhanced Magnetic Resonance Images on Infectious Spondylitis

OBJECTIVE: The purpose of this study is to analyze the patterns of intervertebral disc enhancement seen in infectious spondylitis, differentiate between two groups(tuberculous vs pyogenic spondylitis). METHODS: Between January 1994 and December 2002, 83patients underwent operative procedure with confirmed to histopathologic evaluation. Magnetic resonance(MR) images were obtained in all patients and were analyzed retrospectively. 57patients had tuberculosis and 26patients were infected by pyogens. The patterns of gadolinium enhancement of disc were classified into 4 types(post's classification): Type I, non-enhancing; Type II, enhancement of the peripheral rim; Type III, Type II with central area and partial endplate; Type IV, general enhancement. RESULTS: The enhancement patterns observed were as follows: Common pattern of tuberculous spondylitis was Type II, and pyogenic spondylitis was Type III.(p<0.01) This difference may result from pathophysiologic varieties of organisms. CONCLUSION: Careful preoperative MR analysis of the patterns of disc enhancement occuring in infectious spondylitis can be useful for differentiating between the tuberculous and pyogenic spondylitis.

Gd(DTPA)2--enhanced, and Quantitative MR Imaging in Articular Cartilage

PURPOSE: Early degeneration of articular cartilage is accompanied by a loss of glycosaminoglycan (GAG) and the consequent change of the integrity. The purpose of this study was to biochemically quantify the loss of GAG, and to evaluate the Gd(DTPA)2--enhanced, and T1, T2, rho relaxation map for detection of the early degeneration of cartilage. MATERIALS AND METHODS: A cartilage-bone block in size of 8mmx10 mm was acquired from the patella in each of three pigs. Quantitative analysis of GAG of cartilage was performed at spectrophotometry by use of dimethylmethylene blue. Each of cartilage blocks was cultured in one of three different media: two different culture media (0.2 mg/ml trypsin solution, 1mM Gd (DTPA)2- mixed trypsin solution) and the control media (phosphate buffered saline (PBS)). The cartilage blocks were cultured for 5 hrs, during which MR images of the blocks were obtained at one hour interval (0 hr, 1 hr, 2 hr, 3 hr, 4 hr, 5 hr). And then, additional culture was done for 24 hrs and 48 hrs. Both T1-weighted image (TR/TE, 450/22 ms), and mixed-echo sequence (TR/TE, 760/21-168ms; 8 echoes) were obtained at all times using field of view 50 mm, slice thickness 2 mm, and matrix 256x512. The MRI data were analyzed with pixel-by-pixel comparisons. The cultured cartilage-bone blocks were microscopically observed using hematoxylin & eosin, toluidine blue, alcian blue, and trichrome stains. RESULTS: At quantitation analysis, GAG concentration in the culture solutions was proportional to the culture durations. The T1-signal of the cartilage-bone block cultured in the Gd(DTPA)2- mixed solution was significantly higher (42% in average, p0.05). However the focal increase in T1 relaxation time at superficial and transitional layers of cartilage was seen in Gd(DTPA)2- mixed culture. Toluidine blue and alcian blue stains revealed multiple defects in whole thickness of the cartilage cultured in trypsin media. CONCLUSION: The quantitative analysis showed gradual loss of GAG proportional to the culture duration. Microimagings of cartilage with Gd(DTPA)2--enhancement, relaxation maps were available by pixel size of 97.9x195 micrometer. Loss of GAG over time better demonstrated with Gd(DTPA)2--enhanced images than with T1, T2, rho relaxation maps. Therefore Gd(DTPA)2--enhanced T1-weighted image is superior for detection of early degeneration of cartilage.