Non-invasive assessment of liver disease in rats using multiparametric magnetic resonance imaging: a feasibility study

Non-invasive quantitation of liver disease using multiparametric magnetic resonance imaging (MRI) could refine clinical care pathways, trial design and preclinical drug development. The aim of this study was to evaluate the use of multiparametric MRI in experimental models of liver disease. Liver injury was induced in rats using 4 or 12 weeks of carbon tetrachloride (CCl₄) intoxication and 4 or 8 weeks on a methionine and choline deficient (MCD) diet. Liver MRI was performed using a 7.0 Tesla small animal scanner at baseline and specified timepoints after liver injury. Multiparametric liver MRI parameters [T1 mapping, T2* mapping and proton density fat fraction (PDFF)] were correlated with gold standard histopathological measures. Mean hepatic T1 increased significantly in rats treated with CCl₄ for 12 weeks compared to controls [1122±78 ms versus 959±114 ms; d=162.7, 95% CI (11.92, 313.4), P=0.038] and correlated strongly with histological collagen content (r_s=0.717, P=0.037). In MCD diet-treated rats, hepatic PDFF correlated strongly with histological fat content (r_s=0.819, P<0.0001), steatosis grade (r_s=0.850, P<0.0001) and steatohepatitis score (r_s=0.818, P<0.0001). Although there was minimal histological iron, progressive fat accumulation in MCD diet-treated livers significantly shortened T2*. In preclinical models, quantitative MRI markers correlated with histopathological assessments, especially for fatty liver disease. Validation in longitudinal studies is required.

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Summary: Multiparametric liver MRI was feasible in experimental rat models and imaging parameters correlated with gold standard histopathological assessments, especially characteristics of fatty liver disease.

The use of nuclear magnetic resonance in the diagnosis of lateral canal entrapment

The use of nuclear magnetic resonance (NMR) in the diagnosis of radicular pain due to lateral canal stenosis in 21 patients is reported. NMR was able to distinguish normal intervertebral discs from degenerate discs, and NMR evidence of reduction of epidural fat was more reliable than radiculography in identifying lateral root entrapment. NMR is an important advance in the investigation of lumbar radiculopathies.

Imaging the pregnant human uterus with nuclear magnetic resonance

Nuclear magnetic resonance (NMR) techniques have been used to produce images of the pregnant and nonpregnant human uterus. A series of pictures is presented showing the normal nonpregnant uterus and pelvic organs, the uterus and its contents in pregnancy at 17, 30, and 40 weeks' gestation, and the pelvic organs in the early puerperium. In early pregnancy the uterus and placenta are clearly seen and the dimensions and configuration of the pelvis can be readily assessed. Because of the relatively long scan time of 2 minutes, better images of the fetus were obtained in the third trimester when movement is more restricted. The potential value of this technique in obstetrics is discussed.

Imaging ovarian tumours by nuclear magnetic resonance

The application of nuclear magnetic resonance imaging to the diagnosis of ovarian tumours has been studied in a group of seven patients with ovarian masses and several healthy volunteers who provided examples of normal pelvic anatomy. In three patients, benign unilocular ovarian cysts were demonstrated and in three patients, recurrent ovarian tumours were identified and the extent of the tumours defined. One patient with bilateral ovarian endometriomas was imaged. Endometrial cysts, like masses in other systems which contain blood or lipid-rich material, show high-density images whereas malignant tumours show tissue densities closer to those of normal tissues. The potential value of this technique in the assessment of pelvic disease is discussed.