Van Dyck Pieter, Vanhoenacker Filip M, Gielen Jan L, Dossche Lieven, Weyler Joost, Parizel Paul M
Department of Radiology, University Hospital Antwerp and University of Antwerp, Antwerp (Edegem), Belgium.
Acta Radiol. 2010 Apr;51(3):296-301. doi: 10.3109/02841850903515403.
The significance of borderline magnetic resonance (MR) findings that are equivocal for a tear of the knee meniscus remains uncertain. Given their higher signal-to-noise ratio (SNR) and greater spatial resolution, these equivocal meniscal tears could be expected to be less frequent using a 3.0T MR system.
To investigate the prevalence of equivocal meniscal tears using 3.0T MR, and to study their impact on MR accuracy compared with arthroscopy in the detection of meniscal tears.
The medical records of 100 patients who underwent 3.0T MR imaging and subsequent arthroscopy of the knee were retrospectively reviewed. Two observers interpreted MR images in consensus, and menisci were diagnosed as torn (abnormality on two or more images), equivocal for a tear (abnormality on one image), or intact, using arthroscopy as the standard of reference. The prevalence of equivocal meniscal tears was assessed, and MR accuracy was calculated as follows: first, considering both torn menisci and equivocal diagnoses as positive for a tear; and second, considering only torn menisci as positive for a tear.
Evidence of meniscal tears on MR images was equivocal in 12 medial (12%) and three lateral (3%) menisci. Of these equivocal MR diagnoses, tears were found at arthroscopy in eight medial and one lateral meniscus. In our study, the specificity and positive predictive value increased for both the medial and lateral meniscus when only menisci with two or more abnormal images were considered to be torn: from 80% and 89% to 91% and 94% for the medial meniscus, and from 91% and 73% to 93% and 78% for the lateral meniscus, respectively.
Subtle findings that are equivocal for a tear of the knee meniscus still make MR diagnosis difficult, even at 3.0T. We recommend that radiologists should rather be descriptive in reporting subtle or equivocal MR findings, alerting the clinician of possible meniscal tear.
膝关节半月板撕裂的边缘磁共振（MR）表现不明确，其意义仍不确定。鉴于3.0T MR系统具有更高的信噪比（SNR）和更大的空间分辨率，预计这些不明确的半月板撕裂会较少见。
研究使用3.0T MR时不明确半月板撕裂的患病率，并研究其在半月板撕裂检测中与关节镜检查相比对MR准确性的影响。
回顾性分析100例行3.0T MR成像及随后膝关节镜检查患者的病历。两名观察者共同解读MR图像，以关节镜检查为参考标准，将半月板诊断为撕裂（在两张或更多图像上有异常）、撕裂不明确（在一张图像上有异常）或完整。评估不明确半月板撕裂的患病率，并按以下方法计算MR准确性：首先，将撕裂的半月板和不明确诊断都视为撕裂阳性；其次，仅将撕裂的半月板视为撕裂阳性。
12个内侧半月板（12%）和3个外侧半月板（3%）的MR图像上半月板撕裂的证据不明确。在这些不明确的MR诊断中，关节镜检查发现8个内侧半月板和1个外侧半月板有撕裂。在我们的研究中，当仅将有两张或更多异常图像的半月板视为撕裂时，内侧和外侧半月板的特异性和阳性预测值均增加：内侧半月板从80%和89%分别增至91%和94%，外侧半月板从91%和73%分别增至93%和78%。
即使在3.0T时，膝关节半月板撕裂不明确的细微表现仍使MR诊断困难。我们建议放射科医生在报告细微或不明确的MR表现时应更具描述性，提醒临床医生可能存在半月板撕裂。
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