Validation of a semi-automated technique to accurately measure abdominal fat distribution using CT and MRI for clinical risk stratification

Abstract

The method described is highly reproducible and independent of rater bias. A strong interchangeable relationship exists between calculations of AFD on retrospective CT and MRI. Advances in knowledge: This is the first technique to be applicable to scans that are not performed sequentially or in a research setting. Analysis is semi-automated and results can be compared directly, regardless of imaging modality or patient position. This method has clinical utility in prospective risk stratification and will be applicable to many clinical specialities.

Pelvic MRI and CT Images are Interchangeable for Measuring Peripouch Fat

“…In our study, measurements based on MRI-DIXON were significantly higher than CT images, in terms of perianal fat thickness, AreaM and AreaH. These results were contrary to Waduud's study, which found that MRI measurements of total abdominal area and abdominal waist circumference were lower than the counterpart CT measurements 21 . But in Waduud's study, CT scan was performed in the supine position while MRI scan was performed in the prone position, and the differences were attributed to different patient positions.…”

“…Strong correlations had been reported between MRI and CT images when measuring abdominal visceral fat 25 . Thereafter, several studies had verified the reliability of prospective and retrospective measurements of abdominal visceral fat using CT and MRI [18][19][20][21] . The reported results in abdominal visceral fat were consistent with what we found in peripouch fat.…”

“…Using this technique, only manual circling of peripouch fat (regions of interest) was required. This approach has the advantage of minimizing interobserver and intraobserver differences, and it is much more subjective and time-saving compared with individualized threshold 21 . We only used a single slice technique rather than a volume-based technique for assessment of peripouch fat.…”

“…MRI does not involve radiation exposure, which allows for frequent repeat imaging and it could be applied in at-risk patients, such as pregnant women 18 . Furthermore, MRI is superior to CT in measuring fat, as fat has a typical short longitudinal relaxation time which makes it easy to be differentiated from other adjacent tissues in MRI image 21 . Since both CT and MRI scans have their own advantage, disadvantage, indication and contraindication, respectively, so it is very important to explore whether they are interchangeable.…”

“…For MRI-DXION-F images, the threshold was automatically set at the midpoint between the two peaks of the identified signal intensities in the histograms (Fig. 6g), and fat area was highlighted automatically in almost all images 21 . For CT images, the thresholds were set at a fixed range (Fig.…”