Radio-frequency-induced thermal lesions: subacute magnetic resonance appearance and histological correlation

PURPOSE: To investigate the relationship between subacute magnetic resonance (MR) images of radio-frequency (RF) ablation lesions and tissue viability as determined from histological tissue samples. MATERIALS AND METHODS: We generated lesions (N = 5) in a rabbit thigh model. Four days later, we obtained in vivo T(2)- and contrast-enhanced (CE) T(1)-weighted images and ex vivo histological samples approximately perpendicular to the electrode path. Using three-dimensional registration and warping, we spatially compared manually segmented boundaries apparent on MR images to boundaries separating distinct histological zones determined from hematoxylin and eosin (H&E) and Masson trichrome (MT) stains, as well as birefringence studies. RESULTS: Lesions have a characteristic MR appearance: an outer hyperintense margin (M2) separating background tissue (M3) from an inner core (M1), in both T(2) and CE T(1) images. Histologically, there are two zones of damage: an outer zone of likely nonviable cells (H2) separating background tissue (H3) from an inner core of coagulated nonviable cells (H1). We measured distances between automatically computed correspondence points along histological and MR boundaries. For T(2) and CE T(1) images, respectively, M1 vs. H1 distances were 0.72 +/- 0.99 mm (mean +/- SD) and 0.10 +/- 0.95 mm, while outer M2 vs. H2 boundary distances were 0.26 +/- 1.16 mm and 0.05 +/- 1.08 mm. The discrepancy between histological and MR boundaries was larger than the variability in segmenting MR images, but probably within registration error. There were no significant differences between T(2) and CE T(1) boundaries. CONCLUSION: Lesion boundaries apparent in both T(2)- and CE T(1)-weighted MR scans, performed several days postablation, similarly predict the histological response. That is, the lesion core (M1) corresponds to nonviable coagulated cells (H1), while the hyperintense margin (M2) corresponds to likely nonviable cells undergoing necrotic changes (H2).     

Hepatocellular carcinoma treated with radio frequency ablation: an early evaluation with magnetic resonance imaging

PURPOSE: To determine the usefulness of nonenhanced T1-weighted spoiled gradient-recalled acquisition in the steady-state (SPGR) MRI in the early assessment of the efficacy of radio frequency (RF) therapy for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: A total of 23 patients with 28 HCC nodules treated with percutaneous RF ablation underwent nonenhanced MRI within two days after the RF procedure and contrast-enhanced computed tomography (CT) one week after. MR assessment of ablation efficacy according to the concentric zonal pattern on T1-weighted SPGR imaging was compared with the one-week CT and presence of local recurrence by means of follow-up study for 12 months or more. RESULTS: In 18 of 28 ablated nodules, SPGR images revealed a central hyperintense zone covering the entire tumor, CT showed a nonenhanced area covering the entire tumor, and no local recurrence was demonstrated in the follow-up studies. In nine of 28 nodules, the central hyperintense zone did not cover the entire tumor; and local recurrence was demonstrated in three nodules. In the remaining one nodule, no signal change was seen in the treated area on SPGR images and CT showed the presence of residual viable tumor. CONCLUSION: Nonenhanced T1-weighted MRI was considered useful for early assessment of the efficacy of RF therapy for HCC.     

Three-dimensional method for comparing in vivo interventional MR images of thermally ablated tissue with tissue response

PURPOSE: To investigate the ability of magnetic resonance (MR) to monitor radio-frequency (RF) ablation treatments by comparing MR images of thermal lesions to histologically assayed cellular damage. We developed a new methodology using three-dimensional registration for making spatial correlations. MATERIALS AND METHODS: A low-field, open MRI system was used to guide an ablation probe into rabbit thigh muscle and acquire MR volumes after ablation. After fixation, we sliced and photographed the tissue at 3-mm intervals, using a specially designed apparatus, to obtain a volume of tissue images. Histologic samples were digitized using a video microscopy system. For our three-dimensional registration method, we used the tissue images as the reference, and registered histology and MR images to them using two different computer alignment steps. First, the MR volume was aligned to the volume of tissue images by registering needle fiducials placed near the tissue of interest. Second, we registered the histology images with the tissue images using a two-dimensional warping technique that aligned internal features and the outside boundary of histology and tissue images. RESULTS: The MR and histology images were very well aligned, and registration accuracy, determined from displacement of needle fiducials, was 1.32 +/- 0.39 mm (mean +/- SD), which compared favorably to the MR voxel dimensions (0.70 mm in-plane and 3.0 mm thick). A preliminary comparison of MR and tissue response showed that the region inside the elliptical hyperintense rim in MR closely corresponds to the region of necrosis as established by histology, with a mean absolute distance between MR and histology boundaries of 1.17 mm, slightly smaller than the mean registration error. The MR region slightly overestimated the region of necrosis, with a mean signed distance between boundaries of 0.85 mm. CONCLUSION: Our results suggest that our methodology can be used to achieve three-dimensional registration of histology and in vivo MR images. In MR lesion images, the inner border of the hyperintense region corresponds to the border of irreversible cell damage. This is good evidence that during RF ablation treatments, iMRI lesion images can be used for real-time feedback.     

Sub-acute changes in lesion conspicuity and geometry following MR-guided radiofrequency ablation

PURPOSE: To evaluate MR signal and lesion zone volume evolution through the sub-acute phase following image-guided radiofrequency (RF) thermal ablation. MATERIALS AND METHODS: For many tissues, including muscle and liver, thermal lesions that result from RF heating have a characteristic two-boundary appearance featuring an inner core (zone I) surrounded by a hyper-intense margin (zone II) and normal tissue (zone III), found in both T(2) and contrast enhanced (CE) T(1)-weighted MR images, both immediately post-ablation and four days later. First, we compared corresponding points between manually segmented zone boundaries apparent in T(2)- and CE T(1)-weighted images. Second, we examined the contrast-to-noise ratio (CNR) between all zone combinations. Third, we quantified the volume of zone I, zone II, and the entire lesion using a three-dimensional lesion geometry model fitted to segmented images. RESULTS: On a slice-by-slice basis, no statistically significant differences were found between zone boundaries apparent in T(2) and CE T(1)-weighted images. The contrast to noise ratio (CNR) of zone I vs. zone II, zone I vs. background muscle, and zone II vs. background muscle was always equal or greater for T(2)-weighted images than for CE T(1)-weighted images. In addition, by day four, zone II significantly increased in intensity compared to background muscle. The median Zone I volume increase was 44.2% (42.6%) using T(2) weighted images and 55.5% (68.7% interquartile range) using CE T(1)- weighted images. This expansion likely corresponds to an enlargement of the ablated, coagulative necrosis, region. The median Zone II volume increase was 15.0% (42.6%) using T(2)- weighted images 1.5% (38.8%) using CE T(1)-weighted images. CONCLUSIONS: 1) There are no significant differences between the apparent zone boundaries in T(2)- and CE T(1)-weighted images; 2) CNR is equal or greater for T(2)-weighted images as compared to CE T(1)-images; and 3) both the inner and outer lesion zone volumes typically increase several days post-ablation.     

彩色多普勒超声引导射频消融治疗肝硬化合并小肝癌的疗效观察

目的观察彩色多普勒超声引导下,射频消融治疗肝硬化合并小肝癌患者的临床疗效。方法将120例合并肝硬化的小肝癌患者采用超声引导射频消融治疗,观察其术后近、远期疗效及生存率。结果 120例患者共165个肿瘤,首次完全消融达到80.0%,术后第1、3、5年的总体无瘤生存率分别为80.0%、32.5%、30.0%。肿瘤直径≤3 cm组和>3 cm组比较,≤3 cm组近期疗效优于>3 cm组。结论彩色多普勒超声引导射频消融治疗肝硬化合并小肝癌治疗效果好,对肝功能影响小,并发症少。     

Advanced computer assistance for magnetic resonance-guided microwave thermocoagulation of liver tumors

Rationale and Objectives. The purpose of this study was to utilize computer assistance effectively for both easy and accurate magnetic resonance (MR) image-guided microwave thermocoagulation therapy of liver tumors.

Materials and Methods. An open configuration MR scanner and a microwave coagulator at 2.45 GHz were used. Navigation software, a 3D Slicer, was customized to combine fluoroscopic MR images and preoperative MR images for the navigation. New functions to display MR temperature maps with simple parameter setting, and to record and display the coagulated areas by multiple microwave ablations in the 3-dimensional space (footprinting), were also introduced into the software. The VGA signal of the computer display was directly transferred to the surgeon’s monitor.

Results. The customized software could be used for both accurate image navigation and convenient and easy temperature monitoring. Because repeated punctures and ablations are usually required in this procedure, the footprinting function made targeting of the tumors both easy and accurate and was quite effective in achieving the necessary and sufficient treatment. Furthermore, clear display on the surgeon’s monitor, which was obtained by direct transfer of the VGA signal, enabled precise image navigation.

Conclusion. The newly developed computer assistance was quite useful and helpful for this MR-guided procedure.     

Radiofrequency thermal ablation: correlation of hyperacute MR lesion images with tissue response

PURPOSE: To investigate the hypothesis that the outer boundary of the hyperintense region observed in hyperacute (several minutes post-ablation) T2 and gadolinium contrast-enhanced (CE) T1-weighted magnetic resonance (MR) lesion images is an accurate predictor of eventual cell death from radiofrequency (RF) thermal ablation. MATERIALS AND METHODS: A low-field, open MR imaging system was used to guide an ablation electrode into a thigh muscle of five rabbits and acquire in vivo T2 and CE T1-weighted MR volumes. Ablation occurred by applying RF current for two minutes with the electrode's temperature maintained at 90 degrees +/- 2 degrees C. After fixation, we sliced and photographed the tissue at 3 mm intervals, using a specially designed apparatus, to obtain a volume of tissue images. Digital images of hematoxylin and eosin (H&E) and Masson trichrome-stained histologic samples were obtained, and distinct regions of tissue damage were labeled using a video microscopy system. After the MR and histology images were aligned using a three-dimensional registration method, we compared tissue damage boundaries identified in histology with boundaries marked in MR images. RESULTS: The lesions have distinct zones of tissue damage histologically: a central zone of necrotic cells surrounded by an outer zone with cells that appeared non-viable and associated with marked interstitial edema. In 14 histology images from five lesions, the inner and outer boundaries of the outer zone were compared with the boundaries of a hyperintense rim that surrounds a central hypointense region in the T2 and CE T1-weighted MR images. For T2 and CE T1-weighted MR images, respectively, the mean absolute distance was 1.04 +/- 0.30 mm (mean +/- SD) and 1.00 +/- 0.34 mm for the inner boundaries, and 0.96 +/- 0.34 mm and 0.94 +/- 0.44 mm for the outer boundaries. The mean absolute distances for T2 and CE T1-weighted MR images were not sufficiently different to achieve statistical significance (P = 0.745, 0.818, for the inner and outer boundary, respectively). CONCLUSION: In hyperacute T2 and CE T1-weighted MR lesion images, observations strongly suggest that the outer boundary of the hyperintense rim corresponds to the region of eventual cell necrosis within a distance comparable to our ability to measure. This is good evidence that during RF ablation procedures, MR lesion images can be used to accurately localize the zone of irreversible tissue damage at the lesion margin.     

Automatic quality assessment in structural brain magnetic resonance imaging

MRI has evolved into an important diagnostic technique in medical imaging. However, reliability of the derived diagnosis can be degraded by artifacts, which challenge both radiologists and automatic computer‐aided diagnosis. This work proposes a fully‐automatic method for measuring image quality of three‐dimensional (3D) structural MRI. Quality measures are derived by analyzing the air background of magnitude images and are capable of detecting image degradation from several sources, including bulk motion, residual magnetization from incomplete spoiling, blurring, and ghosting. The method has been validated on 749 3D T₁‐weighted 1.5T and 3T head scans acquired at 36 Alzheimer's Disease Neuroimaging Initiative (ADNI) study sites operating with various software and hardware combinations. Results are compared against qualitative grades assigned by the ADNI quality control center (taken as the reference standard). The derived quality indices are independent of the MRI system used and agree with the reference standard quality ratings with high sensitivity and specificity (>85%). The proposed procedures for quality assessment could be of great value for both research and routine clinical imaging. It could greatly improve workflow through its ability to rule out the need for a repeat scan while the patient is still in the magnet bore. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Fiducial markers for MR histological correlation in ex vivo or short-term in vivo animal experiments: a screening study

PURPOSE: To test injectable fiducial markers for magnetic resonance (MR) histological correlation in ex vivo or in vivo animal experiments. MATERIALS AND METHODS: A total of 35 potential markers were tested ex vivo in pork muscle. The end-points were: 1) visibility, size, and shape on MR images and at macroscopic examination; 2) 24-hour stability; and 3) microscopic appearance. Selected markers were injected in vivo (rabbit's muscle and breast tumor tissue) to test their three-hour in vivo stability and their potential toxicity. Finally, different dilutions of the two best markers were assessed again through the same screening tests to determine whether their size on MR images could be customized by dilution. RESULTS: Two fluid acrylic paints containing inorganic pigments were found to be potentially interesting markers. On MR images, they created well-defined susceptibility artifacts. The markers made with iridescent bronze paint (iron oxide coated mica particles) were readily visible on microscopy and their size on MR images could be customized by dilution. The iridescent stainless steel paint (iron, chromium, nickel) created ex vivo the smallest markers in tissue but needed colloidal iron staining to be visible on microscopy and could not be easily diluted. CONCLUSION: Fluid acrylic paints are potentially interesting markers for MR histological correlation. Further studies are needed to assess their long-term properties.     

Calibration of the radio frequency field for magnetic resonance imaging

We have developed and validated the performance of a novel slice selective pulse sequence that allows direct calibration of the RF field using a simple rectangular pulse. The new sequence offers a number of substantial advantages. It operates at steady state and has an accurate calibration response at short repetition times. The slice selection train is insensitive to RF field strength changes caused by patient loading. The issue of patient motion has been addressed in our data collection and analysis routines. The applicability of the method to human scanning has been demonstrated in the automated RF power calibration routine of a commercial imaging system.     

Temperature quantification using the proton frequency shift technique: In vitro and in vivo validation in an open 0.5 tesla interventional MR scanner during RF ablation

Open magnetic resonance (MR) scanners allow MR-guided targeting of tumors, as well as temperature monitoring of radio frequency (RF) ablation. The proton frequency shift (PFS) technique, an accurate and fast imaging method for temperature quantification, was used to synthesize thermal maps after RF ablation in an open 0.5 T MR system under ex vivo and in vivo conditions. Calibration experiments with 1.5% agarose gel yielded a chemical shift factor of 0.011 +/- 0.001 ppm/ degrees C (r2 = 0.96). Three gradient echo (GRE) pulse sequences were tested for thermal mapping by comparison with fiberoptic thermometer (Luxtron Model 760) readings. Temperature uncertainty decreased from high to low bandwidths (BW): +/-5.9 degrees C at BW = 15.6 kHz, +/-1.4 degrees C at BW = 3.9 kHz, and +/-0.8 degrees C at BW = 2.5 kHz. In vitro experiments (N = 9) in the paraspinal muscle yielded a chemical shift factor of 0.008 +/- 0.001 ppm/ degrees C. Temperature uncertainty was determined as +/-2.7 degrees C (BW = 3.9 kHz, TE = 19.3 msec). The same experiments carried out in the paraspinal muscle (N = 9) of a fully anesthetized pig resulted in a temperature uncertainty of +/-4.3 degrees C (BW = 3.9 kHz, TE = 19.3 msec), which is higher than it is in vitro conditions (P < 0.15). Quantitative temperature monitoring of RF ablation is feasible in a 0.5 T open-configured MR scanner under ex vivo and in vivo conditions using the PFS technique.     

彩色多普勒血流显像随访54例射频治疗肝癌的疗效观察

 目的应用彩色多普勒血流显像(Color Dopplerflow imaging,CDFI)评价集束电极射频(简称射频)治疗肝癌6～18月的疗效。方法应用CDFI对射频治疗前及治疗后6、12和18月的肝癌患者肿块及肝动脉的血流动力学情况进行观察。结果射频治疗后6、12、18月肿块血流信号消失或明显减少,血流信号消失率分别为73.5％、51.1％、41.2％;仍能检测到血流信号的肿块最大血流速度(Vmax)及及阻力指数(RI)无明显变化;肝动脉的内径、Vmax及RI降低。结论CDFI对集束电极射频治疗肝癌后的血流动力学变化的疗效判断具有重要临床意义。     

Three-dimensional model of lesion geometry for evaluation of MR-guided thermal ablation therapy

RATIONALE AND OBJECTIVES: High-radiofrequency energy is used clinically to ablate pathologic tissue with interventional magnetic resonance (MR) imaging. For many tissues, resulting lesions have a characteristic appearance on contrast-enhanced T1- and T2-weighted MR images, with two boundaries enclosing an inner hypointense region and an outer hyperintense margin. Geometric modeling of three-dimensional thermal lesions in animal experiments and patient treatments would improve analyses and visualization. MATERIALS AND METHODS: The authors created a model with two quadric surfaces and 12 parameters to describe both lesion surfaces. Parameters were estimated with iterative optimization to minimize the sum of the squared shortest distances from segmented points to the model surface. The authors validated the estimation process with digital lesion phantoms that simulated varying levels of segmentation error and missing surface information. They also applied their method to in vivo images of lesions in a rabbit model. RESULTS: For simulated phantom lesions, the lesion geometry was accurate despite manual segmentation error and incomplete surface data. Even when 50% of the surface was missing, the median error was less than 0.5 mm. For all in vivo lesions, the median distance from the model surface to data was no more than 0.58 mm for both inner and outer surfaces, less than a voxel width (0.7 mm). The interquartile range was 0.89 mm or less for all data. CONCLUSION: The authors' model provides a good approximation of actual lesion geometry and is highly resistant to missing segmentation information. It should prove useful for three-dimensional lesion visualization, volume estimation, automated segmentation, and volume registration.     

Methods for registration of magnetic resonance images of ex vivo prostate specimens with histology

Purpose:

To evaluate two methods of scanning and tissue processing to achieve accurate magnetic resonance (MR)‐histologic correlation in human prostate specimens.

Materials and Methods:

Two prostates had acrylic paint markers injected to define the plane of imaging and serve as internal fiducials. Each was placed on a polycarbonate plane‐finder device (PFD), which was adjusted to align the imaging and cutting planes. Three prostates were aligned by use of a plane finder key (PFK), a polycarbonate plate that locks the specimen in a cylindrical carrier. Markers were injected for registration analysis. Prostates were imaged, then sectioned. Imaging software was used to create registration maps of the MR and histology images. Measurements between control points were made and compared.

Results:

Accurate correlation was achieved between MR and histologic images. The mean displacement (MD) between the corresponding registration points using the PFD technique ranged from 1.11–1.38 mm for each section. The MD for all sections was 1.24 mm. The MD using the PFK technique ranged from 0.79–1.01 mm for each section, and the MD across all sections for the PFK was 0.92 mm.

Conclusion:

We describe two methods that can achieve accurate, reproducible correlation between MR imaging and histologic sections in human prostatectomy specimens. J. Magn. Reson. Imaging 2012;36:206–212. © 2012 Wiley Periodicals, Inc.     

MR appearances of radiofrequency thermal ablation region: histopathologic correlation with dog liver models and an autopsy case

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the utility of magnetic resonance (MR) imaging for indicating the extent of true tissue necrosis of the liver after radiofrequency (RF) ablation in comparison with histopathologic findings in dog models and an autopsy case. MATERIALS AND METHODS: RF ablation of the liver parenchyma was performed on three dogs under general anesthesia. MR appearances of the RF-ablated regions on T1-weighted fast-low angle shot (FLASH; repetition time/echo time [TR/TE]/flip angle: 120/3.8/70),T2-weighted turbo spin echo (3000/80/echo train = 25) and contrast-enhanced T1-weighted images were compared with histopathologic findings. An autopsy case with hepatocellular carcinoma was also enrolled in this study. RESULTS: All ablated regions showed three zones on T1-weighted FLASH images: a central zone with low intensity, a broad hyperintense middle zone, and a surrounding hypointense band. The central and middle zones corresponded to the degrees of coagulation necrosis observed during histopathologic examination, whereas no viable cells were seen in these zones during the microscopic examination using nicotinamide adenine dinucleotide diaphorase stain. The surrounding hypointense band corresponded to sinusoidal congestion in the acute phase and to fibrotic change in the subacute phase. CONCLUSION: MR imaging using the FLASH sequence can accurately determine the extent of the necrotic area after RF ablation.     

Evaluation of the keyhole technique applied to the proton resonance frequency method for magnetic resonance temperature imaging

Purpose:

To evaluate the temporal and spatial resolution of magnetic resonance (MR) temperature imaging when using the proton resonance frequency (PRF) method combined with the keyhole technique.

Materials and Methods:

Tissue‐mimicking phantom and swine muscle tissue were microwave‐heated by a coaxial slot antenna. For the sake of MR hardware safety, MR images were sequentially acquired after heating the subjects using a spoiled gradient (SPGR) pulse sequence. Reference raw (k‐space) data were collected before heating the subjects. Keyhole temperature images were reconstructed from full k‐space data synthesized by combining the peripheral phase‐encoding part of the reference raw data and the center phase‐encoding keyhole part of the time sequential raw data. Each keyhole image was analyzed with thermal error, and the signal‐to‐noise ratio (SNR) was compared with the self‐reference (nonkeyhole) images according to the number of keyhole phase‐encoding (keyhole‐data size) portions.

Results:

In applied keyhole temperature images, smaller keyhole‐data sizes led to more temperature error increases, but the SNR did not decreased comparably. Additionally, keyhole images with a keyhole‐data size of <16 had significantly different temperatures compared with fully phase‐encoded self‐reference images (P < 0.05).

Conclusion:

The keyhole technique combined with the PRF method improves temporal resolution and SNR in the measurement of the temperature in the deeper parts of body in real time. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.     

Quantitative magnetic resonance temperature mapping for real-time monitoring of radiofrequency ablation of the liver: an ex vivo study

We evaluated the feasibility and accuracy of real-time magnetic resonance (MR) thermometry for monitoring radiofrequency (RF) ablation in the liver. Continuous MR temperature mapping was used to monitor bipolar RF ablations performed in ex vivo livers with and without flow using two parallel electrodes. Macroscopic inspection of ablation zones was compared with thermal dose maps (TDm) and T1-weighted inversion recovery turbo spin echo (IR-TSE) images for their size and shape and the influence of flow. Pearson’s correlation (r), Bland and Altman tests and kappa (χK) tests were performed. The mean differences in ablation zone size between macroscopic and TDm and IR-TSE measurements were +4 mm and −2 mm, respectively. TDm was well correlated with macroscopy (r=0.77 versus r=0.44 for IR-TSE). TDm was found to be more precise for shape recognition (χK=0.73 versus χK=0.55 for IR-TSE) and for detection of an intact ring of liver due to the cooling effect of flow which was impossible with IR-TSE. Simultaneous monitoring of RF ablation by MR thermometry is feasible and reliable for predicting the shape of ablation zones and the impact of the heat-sink effect of flow. Further studies are needed to confirm these results in vivo.Electronic Supplementary Material Supplementary material is available for this article at Grant Support: Ligue National Contre le Cancer, French Ministry of Research and Philips Medical Systems.     

Automatic tuning and matching of a small multifrequency saddle coil at 4.7 T.

A new circuit design for automatically tuning and matching a saddle coil for small animal imaging is presented. This design allows working at (1)H, (19)F, and (3)He resonance frequencies in a 4.7 T spectrometer. It is based on a balanced circuit with commercial variable capacity diodes controlled by a computer using digital potentiometers. The change between two different frequencies can be accurately performed in a few seconds. System Q is compared, between 140-210 MHz, to the same coil tuned and matched with high Q variable capacitors. Differences lower than 5% were found with a loaded coil. The proposed design has initially been evaluated in (19)F and (1)H NMR images acquired with a five-tube phantom. An application is also shown for the acquisition of (3)He, (19)F, and (1)H lung images in a control rat.     

正常前交叉韧带高频超声和MRI测量对照分析

 目的 探讨应用高频超声测量前交叉韧带(anterior cruciate ligament, ACL)厚径的可行性及准确性。方法 选择2015-01至2015-09现役男性军人健康志愿者30名,分别应用高频超声及MRI测量右膝关节ACL胫骨止点端厚径。对比分析两名不同医师应用高频超声测量ACL厚径的结果,再对比分析应用高频超声及MRI测量ACL厚径的结果。结果 两名医师应用高频超声测量ACL厚径具有较好的一致性及可重复性,其组内相关系数ICC=0.934,95%区间为(0.867,0.968);使用Bland-Altman法分析:两位医师测量ACL厚径差值(mm)均值为-0.04,95%区间为(-0.55,0.47)。应用高频超声与MRI测量ACL厚径具有较好的一致性,提示两种方式是可替代的;其组内相关系数ICC=0.914,95%区间为(0.822,0.959);使用Bland-Altman法分析:应用高频超声与MRI测量ACL厚径差值(mm)均值为0.04,95%区间为(-0.62,0.70)。结论 高频超声可作为测量膝关节ACL厚径的常规方法。