Bahman Kasmai

Developing a new measure of small bowel peristalsis with dynamic MR: a proof of concept study

Background Small bowel peristalsis is a complex of many individual motion elements. Although each element of peristalsis can be measured there is no current global measure of peristalsis. Purpose To examine the feasibility of automated computerized assessment of global small bowel motility using simple computational methods. Material and Methods Coronal dynamic MR images were obtained from five healthy volunteers who had fasted for 9 h and drunk 1.5 L of water. Images were taken using single breath-hold and ECG triggering. Acquisitions were repeated at 10 and 20 min after an intramuscular injection of hyoscine butylbromide. Parametric maps were generated representing the mean change in signal amplitude (MSA) per voxel for each dynamic acquisition. Two observers independently assessed thresholding for optimal segmentation of small bowel from other sources of signal. Total voxel activity (TVA) for each study was calculated as a sum of MSA per slice and whole examination and TVA profiles were generated. Results Independent observations suggest that the automated segmentation method described usefully segments small bowel activity from other signal. Small bowel movement represented as TVA varied three-fold in the five volunteers and was inhibited by anti-muscarinic injection. Conclusion It is possible to develop a new measure, based on automated segmentation of mean signal amplitude changes, of small bowel peristalsis using dynamic MR.

Quantitative analysis of tibial subchondral bone: Texture analysis outperforms conventional trabecular microarchitecture analysis.

The aim of this study was to compare two different methods of quantitative assessment of tibial subchondral bone in osteoarthritis (OA): statistical texture analysis (sTA) and trabecular microarchitecture analysis (tMA).

Test–retest reliability of rapid whole body and compartmental fat volume quantification on a widebore 3T MR system in normal-weight, overweight, and obese subjects

To measure the test–retest reliability of rapid (<15 min) whole body and visceral fat volume quantification in normal and obese subjects on a widebore 3T MR system and compare it with conventional manual segmentation.

MRI texture analysis of subchondral bone at the tibial plateau

ObjectivesTo determine the feasibility of MRI texture analysis as a method of quantifying subchondral bone architecture in knee osteoarthritis (OA).MethodsAsymptomatic subjects aged 20–30 (group 1, n = 10), symptomatic patients aged 40–50 (group 2, n = 10) and patients scheduled for knee replacement aged 55–85 (group 3, n = 10) underwent high spatial resolution T1-weighted coronal 3T knee MRI.Regions of interest were created in the medial (MT) and lateral (LT) tibial subchondral bone from which 20 texture parameters were calculated. T2 mapping of the tibial cartilage was performed in groups 1 and 2. Mean parameter values were compared between groups using ANOVA. Linear discriminant analysis (LDA) was used to evaluate the ability of texture analysis to classify subjects correctly.ResultsSignificant differences in 18/20 and 12/20 subchondral bone texture parameters were demonstrated between groups at the MT and LT respectively. There was no significant difference in mean MT or LT cartilage T2 values between group 1 and group 2.LDA demonstrated subject classification accuracy of 97 % (95 % CI 91–100 %).ConclusionMRI texture analysis of tibial subchondral bone may allow detection of alteration in subchondral bone architecture in OA. This has potential applications in understanding OA pathogenesis and assessing response to treatment.Key Points• Improved techniques to monitor OA disease progression and treatment response are desirable• Subchondral bone (SB) may play significant role in the development of OA• MRI texture analysis is a method of quantifying changes in SB architecture• Pilot study showed that this technique is feasible and reliable• Significant differences in SB texture were demonstrated between individuals with/without OA

Physiology of the small bowel: A new approach using MRI and proposal for a new metric of function

BACKGROUND The mechanics of small bowel motility are extremely complex. Routine clinical access to small bowel has been restricted to radiological enteric contrast studies which have not contributed significantly to the understanding of small bowel physiology. Small bowel mechanics are understood within a framework of individual visible or measurable elements such as peristaltic wave formation, intra-luminal pressure gradients and transit times. There are no global measures of small bowel function that can be readily obtained in vivo in humans. Magnetic resonance imaging (MRI) is playing an increasingly important role in radiological diagnosis of small bowel disease and dynamic MRI offers the possibility of capturing small bowel movement in three-dimensional cinematic datasets. The metrics that are used to describe small bowel mechanics, typically anatomical measures in isolated segments, are not suited to analysing these large dynamic datasets. The proposal in this paper is to leave behind all previously described anatomical metrics and to describe anew the mechanics of small bowel movement in mathematical terms derived from changes in pixel intensity within dynamic MRI datasets so that global small bowel activity might be summarised in a single novel metric. HYPOTHESIS The hypothesis of this paper is that global small bowel activity can be quantified by a new dynamic MR based metric. EVALUATION A proposed strategy for evaluation includes a progression through feasibility, optimisation, reliability and validation studies. Thereafter normal volunteers would be required in order to define normal ranges for the new metric. These ranges would describe small bowel activity during fasting or after ingestion of fluids and standard meals. Mathematical modelling of the data could follow a two stage approach. The first stage could be to study segmentation or extraction techniques by which the small bowel activity could be isolated from MRI signal generated by the rest of the abdomen. The second stage would be to apply a number of data mining techniques that would identify significant features within the datasets. CONCLUSION If this approach proves to be a useful model for studying small bowel physiology in humans, it would afford significant new avenues of research and treatment particularly in areas such as enteric drug delivery, the ageing gut, and nutrition.

Pharmacokinetic modeling of multislice dynamic contrast-enhanced MRI in normal-healing radial fractures: A pilot study

To define the range of quantitative pharmacokinetic parameters in normal‐healing bone with dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI). DCE‐MRI is an established technique for characterizing abnormal tissue microvasculature within solid tumors, but has also shown promise for assessing bone and bone marrow.