A novel method for measuring bowel motility and velocity with dynamic magnetic resonance imaging in two and three dimensions.

Increasingly, dynamic magnetic resonance imaging (MRI) has potential as a noninvasive and accessible tool for diagnosing and monitoring gastrointestinal motility in healthy and diseased bowel. However, current MRI methods of measuring bowel motility have limitations: requiring bowel preparation or long acquisition times; providing mainly surrogate measures of motion; and estimating bowel-wall movement in just two dimensions. In this proof-of-concept study we apply a method that provides a quantitative measure of motion within the bowel, in both two and three dimensions, using existing, vendor-implemented MRI pulse sequences with minimal bowel preparation. This method uses a minimised cost function to fit linear vectors in the spatial and temporal domains. It is sensitised to the spatial scale of the bowel and aims to address issues relating to the low signal-to-noise in high-temporal resolution dynamic MRI scans, previously compensated for by performing thick-slice (10-mm) two-dimensional (2D) coronal scans. We applied both 2D and three-dimensional (3D) scanning protocols in two healthy volunteers. For 2D scanning, analysis yielded bi-modal velocity peaks, with a mean antegrade motion of 5.5 mm/s and an additional peak at ~9 mm/s corresponding to longitudinal peristalsis, as supported by intraoperative data from the literature. Furthermore, 3D scans indicated a mean forward motion of 4.7 mm/s, and degrees of antegrade and retrograde motion were also established. These measures show promise for the noninvasive assessment of bowel motility, and have the potential to be tuned to particular regions of interest and behaviours within the bowel.

Measuring liver fat fraction with complex-based chemical shift MRI: the effect of simplified sampling protocols on accuracy.

BACKGROUND: The assessment of liver percentage fat fraction (%FF) using proton density fat fraction sequences is becoming increasingly accessible. Previous studies have tended to use multiple small ROIs that focus on Couinaud segments. In an effort to simplify day-to-day analysis, this study assesses the impact of using larger, elliptical ROIs focused on a single hepatic lobe. Additionally, we assess the impact of sampling fewer transhepatic slices when measuring %FF. METHODS: Retrospective analysis of prospectively obtained images from 34 volunteers using an IDEAL IQ sequence. Two observers independently measured %FF using three different protocols: freehand whole-liver ROI (fh-ROI), elliptical-ROI on the right lobe (rt-ROI) and elliptical-ROI on the left lobe (lt-ROI). RESULTS: Inter-observer reliability for all measurements techniques was 'excellent' (Spearman's rank correlation coefficients 0.81-0.98). There was a significant difference (Paired Wilcoxon Test: p < 0.001) between the median %FF obtained using fh-ROI when compared to the rt-ROI method, the maximum mean difference between the two techniques was 2.79% (95% CI). For all sampling methods a Kruskall-Wallis analysis demonstrated no significant difference in mean %FF when the number of slices sampled was reduced from 11 to 1. The mean coefficient of variance increased when more slices were sampled (3 slices = 0.1, 11 slices = 0.17, p < 0.001). CONCLUSION: Simplified ROIs focused on one hepatic lobe provide %FF measurements that are unlikely to be sufficiently accurate for use in clinical practice. Freehand whole-liver ROIs should be used in preference. A single freehand ROI measurement taken at the level of the hepatic hilum yields a %FF that is representative of the mean whole liver % FF. Multiple slices are needed to measure heterogeneity.

Accuracy of high b-value diffusion-weighted MRI for prostate cancer detection: a meta-analysis.

Background The diagnostic accuracy of diffusion-weighted imaging (DWI) to detect prostate cancer is well-established. DWI provides visual as well as quantitative means of detecting tumor, the apparent diffusion coefficient (ADC). Recently higher b-values have been used to improve DWI's diagnostic performance. Purpose To determine the diagnostic performance of high b-value DWI at detecting prostate cancer and whether quantifying ADC improves accuracy. Material and Methods A comprehensive literature search of published and unpublished databases was performed. Eligible studies had histopathologically proven prostate cancer, DWI sequences using b-values ≥ 1000 s/mm2, less than ten patients, and data for creating a 2 × 2 table. Study quality was assessed with QUADAS-2 (Quality Assessment of diagnostic Accuracy Studies). Sensitivity and specificity were calculated and tests for statistical heterogeneity and threshold effect performed. Results were plotted on a summary receiver operating characteristic curve (sROC) and the area under the curve (AUC) determined the diagnostic performance of high b-value DWI. Results Ten studies met eligibility criteria with 13 subsets of data available for analysis, including 522 patients. Pooled sensitivity and specificity were 0.59 (95% confidence interval [CI], 0.57-0.61) and 0.92 (95% CI, 0.91-0.92), respectively, and the sROC AUC was 0.92. Subgroup analysis showed a statistically significant ( P = 0.03) improvement in accuracy when using tumor visual assessment rather than ADC. Conclusion High b-value DWI gives good diagnostic performance for prostate cancer detection and visual assessment of tumor diffusion is significantly more accurate than ROI measurements of ADC.

A monte carlo study of restricted diffusion: Implications for diffusion MRI of prostate cancer.

PURPOSE: Diffusion MRI is used frequently to assess prostate cancer. The prostate consists of cellular tissue surrounding fluid filled ducts. Here, the diffusion properties of the ductal fluid alone were studied. Monte Carlo simulations were used to investigate ductal residence times to determine whether ducts can be regarded as forming a separate compartment and whether ductal radius could determine the Apparent Diffusion Coefficient (ADC) of the ductal fluid. METHODS: Random walks were simulated in cavities. Average residence times were estimated for permeable cavities. Signal reductions resulting from application of a Stejskal-Tanner pulse sequence were calculated in impermeable cavities. Simulations were repeated for cavities of different radii and different diffusion times. RESULTS: Residence times are at least comparable with diffusion times even in relatively high grade tumors. ADCs asymptotically approach theoretical limiting values. At large radii and short diffusion times, ADCs are similar to free diffusion. At small radii and long diffusion times, ADCs are reduced toward zero, and kurtosis approaches a value of -1.2. CONCLUSIONS: Restricted diffusion in cavities of similar sizes to prostate ducts may reduce ductal ADCs. This may contribute to reductions in total ADC seen in prostate cancer. Magn Reson Med 77:1671-1677, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

A model describing diffusion in prostate cancer.

PURPOSE: Quantitative diffusion MRI has frequently been studied as a means of grading prostate cancer. Interpretation of results is complicated by the nature of prostate tissue, which consists of four distinct compartments: vascular, ductal lumen, epithelium, and stroma. Current diffusion measurements are an ill-defined weighted average of these compartments. In this study, prostate diffusion is analyzed in terms of a model that takes explicit account of tissue compartmentalization, exchange effects, and the non-Gaussian behavior of tissue diffusion. METHOD: The model assumes that exchange between the cellular (ie, stromal plus epithelial) and the vascular and ductal compartments is slow. Ductal and cellular diffusion characteristics are estimated by Monte Carlo simulation and a two-compartment exchange model, respectively. Vascular pseudodiffusion is represented by an additional signal at b = 0. Most model parameters are obtained either from published data or by comparing model predictions with the published results from 41 studies. Model prediction error is estimated using 10-fold cross-validation. RESULTS: Agreement between model predictions and published results is good. The model satisfactorily explains the variability of ADC estimates found in the literature. CONCLUSION: A reliable model that predicts the diffusion behavior of benign and cancerous prostate tissue of different Gleason scores has been developed. Magn Reson Med 78:316-326, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

An improved model for prostate diffusion incorporating the results of Monte Carlo simulations of diffusion in the cellular compartment.

The purpose of this work was to refine a previously published model of prostate diffusion by incorporating improved estimates of cellular diffusivity obtained by Monte Carlo simulation. Stromal and epithelial cell size and intracellular volume fraction in different grades of cancer were determined from histological images. Diffusion in different mixtures of cells, corresponding to different tumor grades, was simulated and cellular apparent diffusion coefficient and kurtosis values determined. These values were incorporated into the previously published model of prostate diffusion and model predictions compared with values found in the literature. Stromal cell radius and intracellular volume fraction were 3.74 ± 0.96 µm and 13 ± 3% respectively in normal peripheral zone (PZ), and were similar in all grades of cancer. Epithelial cell radius and intracellular volume fraction were 3.40 ± 0.15 µm and 45 ± 5% respectively in normal PZ, rising to 4.75 ± 0.20 µm and 70 ± 8% in high grade cancer. Cellular apparent diffusion coefficient and kurtosis were 1.02 µm2 ms-1 and 0.58 respectively in normal PZ, and 0.61 µm2 ms-1 and 1.15 in high grade cancer (variation in simulation values are less than 0.1%). Agreement between model predictions and measurements were good, with a mean square error of 0.22 µm2 ms-1 . Incorporation of cellular diffusion coefficient and kurtosis values obtained by Monte Carlo simulation into a model of prostate diffusion gives good agreement with published results.

The role of metalloproteinases and their tissue inhibitors in adipose tissue remodelling and whole-body lipid distribution: a cross-sectional clinical study.

BACKGROUND: Metabolically unhealthy obesity is associated with insulin resistance. Dysfunctional adipose tissue remodelling might explain features of this disorder, such as chronic white adipose tissue inflammation, adipocyte hypertrophy, and ectopic lipid deposition. Metalloproteinases and their tissue inhibitors (TIMPs) have been implicated in human adipose tissue remodelling. In a cross-sectional study, we investigated the association of adipose metalloproteinase and TIMP expression with whole-body lipid distribution and insulin resistance. METHODS: Healthy women undergoing elective surgery donated fasting blood samples (for calculation of homoeostasis model assessment of insulin resistance [HOMA2-IR], the primary outcome). At operation 2 cm(3) biopsy samples of subcutaneous and visceral adipose tissue were obtained. 1 cm(3) was fixed, paraffin-embedded, and stained for adipocyte size quantification, and RNA was extracted from the remaining tissue for quantitative RT-PCR analysis. The women also underwent whole-body MRI for analysis of fat distribution. FINDINGS: 26 women were recruited (mean age 50·3 years, SD 13·1) into five body-mass index categories (18·5-24·9 kg/m(2) [n=12, 46·1%], 25-29·9 [n=6, 23·1%], 30-34·9 [n=3, 11·5%], 35-39·9 [n=3, 11·5%], >40 [n=2, 7·8%]). Mean fasting glucose was 5·29 mmol/L (SD 0·66), mean fasting insulin 71·29 pmol/L (47·72), and mean HOMA2-IR 1·35 (0·91). HOMA2-IR correlated with body-mass index (r=0·73, p<0·0001), subcutaneous and visceral adipose tissue volumes (r=0·94 and r=0·87, respectively; both p<0·0001), and hepatic fat fraction (r=0·57, p=0·013). Visceral adipose tissue MMP14 expression correlated strongly with hepatic fat fraction (r=0·944, p<0·0001), HOMA2-IR (r=0·74, p=0·01), and visceral adipose tissue volume (r=0·74, p=0·036). Subcutaneous adipose tissue TIMP3 expression correlated with subcutaneous adipocyte area (r=0·72, p=0·029), but not with HOMA2-IR (r=-0·53, p=0·062). INTERPRETATION: The results suggest that metalloproteinases and TIMPs regulate adipose tissue remodelling and distribution. MMP14 has been implicated in collagen turnover in pre-adipocyte differentiation, whereas TIMP3 may modulate the shedding of DLK1, a regulator of adipogenesis. In our concurrent in-vitro study, we have shown that human adipocytes express metalloproteinases and TIMPs, and that their expression varies with inflammatory stimulation. These proteins might therefore integrate inflammatory signals with dysregulated adipose remodelling in metabolically unhealthy obesity. FUNDING: British Heart Foundation, Diabetes Research & Wellness Foundation Open Funding 2011.

Does Magnetic Resonance Brain Scanning at 3.0 Tesla Pose a Hyperthermic Challenge to Term Neonates?

Next-generation 3-Tesla magnetic resonance (MR) scanners offer improved neonatal neuroimaging, but the greater associated radiofrequency radiation may increase the risk of hyperthermia. Safety data for neonatal 3-T MR scanning are lacking. We measured rectal temperatures continuously in 25 neonates undergoing 3-T brain MR imaging and observed no significant hyperthermic threat.

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

PURPOSE: 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. MATERIALS AND METHODS: In this study ethical approval for eight patients was obtained. Inclusion criteria were an extra-articular distal radial fracture in patients aged 20-50 years which had united by 6 weeks in plaster cast. This was assessed by an experienced orthopedic surgeon. DCE-MRI was performed at 1.5T 6 weeks after initial injury. The transfer constant (K(trans) ), transfer rate (Kep ), and initial area under the curve (IAUC) values for the fracture site and adjacent marrow were obtained for each patient. RESULTS: The mean T1 , K(trans) , Kep , and IAUC at the fracture site were 1713 (standard deviation [SD] 645), 0.09 (SD 0.07), 0.17 (SD 0.17) and 4.9 (SD 4.4). The relative standard deviation (RSD) for the fracture site ranged from 0.38 to 0.97 and for the adjacent marrow ranged from 0.95-3.88. Within each patient the range of RSDs was 0.04-0.42 for T1 , 0.26-0.91 for K(trans) , 0.14-1.06 for Kep , and 0.35-0.96 for the IAUC. CONCLUSION: Pharmacokinetic measures of perfusion can be obtained from healing fractures using DCE-MRI with "excellent" intraclass correlation coefficients for inter- and intrarater reliability. The use of these perfusion parameters is limited by wide patient-to-patient variation and slice-to-slice variation within patients.

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.

PURPOSE: 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. MATERIALS AND METHODS: Thirty participants (body mass index [BMI] 20.1-48.6 kg/m2 ) underwent two whole-body magnetic resonance imaging (MRI) examinations on a widebore 3T machine using a 2-point Dixon technique. Phase sensitive reconstruction and intensity inhomogeneity correction produced quantitative datasets of total adipose tissue (TAT), abdominal subcutaneous adipose tissue (ASAT), and visceral adipose tissue (VAT). The quantification was performed automatically using nonrigid atlas-based segmentation and compared with manual segmentation (SliceOmatic). RESULTS: The mean TAT was 31.74 L with a coefficient of variation (CV) of 0.79% and a coefficient of repeatability (CR) of 0.49 L. The ASAT was 7.92 L with a CV of 2.98% and a CR of 0.46 L. There was no significant difference in the semiautomated and manually segmented VAT (P = 0.73) but there were differences in the reliability of the two techniques. The mean semiautomated VAT was 2.56 L, CV 1.8%, and CR 0.09 L compared to the mean manually segmented VAT of 3.12 L, where the CV was 6.3% and the CR was 0.39 L. CONCLUSION: Rapid semiautomated whole body and compartmental fat volume quantification can be derived from a widebore 3T system, for a range of body sizes including obese patients, with "almost perfect" test-retest reliability. J. Magn. Reson. Imaging 2016;44:1464-1473.

Parameter Estimation Error Dependency on the Acquisition Protocol in Diffusion Kurtosis Imaging.

Mono-exponential kurtosis model is routinely fitted on diffusion weighted, magnetic resonance imaging data to describe non-Gaussian diffusion. Here, the purpose was to optimize acquisitions for this model to minimize the errors in estimating diffusion coefficient and kurtosis. Similar to a previous study, covariance matrix calculations were used, and coefficients of variation in estimating each parameter of this model were calculated. The acquisition parameter, b values, varied in discrete grids to find the optimum ones that minimize the coefficient of variation in estimating the two non-Gaussian parameters. Also, the effect of variation of the target values on the optimized values was investigated. Additionally, the results were benchmarked with Monte Carlo noise simulations. Simple correlations were found between the optimized b values and target values of diffusion and kurtosis. For small target values of the two parameters, there is higher chance of having significant errors; this is caused by maximum b value limits imposed by the scanner than the mathematical bounds. The results here, cover a wide range of parameters D and K so that they could be used in many directionally averaged diffusion weighted cases such as head and neck, prostate, etc.

Minimization of errors in biexponential T2 measurements of the prostate.

PURPOSE: To determine the echo times that provide the greatest precision in measurements of prostate T2s. T2 relaxation time measurements in the prostate are complicated by the structure of prostate tissue, which consists of fluid-filled glands surrounded by epithelial and stromal cells. Since the glands are large relative to diffusion distances, there is little water exchange between the two compartments and T2s are biexponential. Because the relative size and characteristics of the two compartments change in prostate tumors, accurate measurement of the characteristics of each may provide useful information on tumor grade. MATERIALS AND METHODS: T2s were measured in a group of 25 men with biopsy-proven prostate cancer. Subjects were scanned at 3T with a 16-echo turbo-spin echo T2-mapping sequence. Normal prostate T2s were measured in areas showing no disease. Optimum echo times for measurement of normal prostate T2s were found by calculating the covariance matrix, which provides estimates of parameter variance. Echo times that minimize T2 variance were then found by searching over grids of different echo times. Optima for four to eight echo acquisitions were found. Optima were tested by Monte Carlo simulation. RESULTS: Fast and slow T2s were 60 msec and 360 msec, respectively. The fast signal fraction was 0.6. Optimum echo times were between 0 and 780 msec, depending on the number of echoes acquired. CONCLUSION: Use of optimum echo times can substantially improve the precision of biexponential T2 measurements. This optimization is anticipated to improve prostate cancer characterization using T2 measurements.

Cross-linking of sodium caseinate-structured emulsion with transglutaminase alters postprandial metabolic and appetite responses in healthy young individuals.

The physico-chemical and interfacial properties of fat emulsions influence lipid digestion and may affect postprandial responses. The aim of the present study was to determine the effects of the modification of the interfacial layer of a fat emulsion by cross-linking on postprandial metabolic and appetite responses. A total of fifteen healthy individuals (26.5 (sem 6.9) years and BMI 21.9 (sem 2.0) kg/m2) participated in a cross-over design experiment in which they consumed two isoenergetic (1924 kJ (460 kcal)) and isovolumic (250 g) emulsions stabilised with either sodium caseinate (Cas) or transglutaminase-cross-linked sodium caseinate (Cas-TG) in a randomised order. Blood samples were collected from the individuals at baseline and for 6 h postprandially for the determination of serum TAG and plasma NEFA, cholecystokinin (CCK), glucagon-like peptide 1 (GLP-1), glucose and insulin responses. Appetite was assessed using visual analogue scales. Postprandial TAG and NEFA responses and gastric emptying (GE) rates were comparable between the emulsions. CCK increased more after the ingestion of Cas-TG than after the ingestion of Cas (P< 0.05), while GLP-1 responses did not differ between the two test emulsions. Glucose and insulin profiles were lower after consuming Cas-TG than after consuming Cas (P< 0.05). The overall insulin, glucose and CCK responses, expressed as areas above/under the curve, did not differ significantly between the Cas and Cas-TG meal conditions. Satiety ratings were reduced and hunger, desire to eat and thirst ratings increased more after the ingestion of Cas-TG than after the ingestion of Cas (P< 0.05). The present results suggest that even a subtle structural modification of the interfacial layer of a fat emulsion can alter the early postprandial profiles of glucose, insulin, CCK, appetite and satiety through decreased protein digestion without affecting significantly on GE or overall lipid digestion.

Advances in Metal Artifact Reduction Techniques for Periprosthetic Soft Tissue Imaging.

Artifact from metallic orthopedic prosthesis is caused by inhomogeneity in the B0 magnetic field, particularly in the frequency encoding direction. This results in signal voids, signal pileup, and geometric distortion. Advances in reducing this artifact allow us to assess the complications of joint replacement and improve imaging of nearby tissues such as within the pelvis. Selection of titanium implants and lower field strength MR units provide optimal conditions for artifact reduction. Conventional sequences can be optimized by using inversion recovery sequences, large matrices, high receiver bandwidths, and thin slices. Optimizing these parameters comes with a penalty in terms of signal-to-noise ratio or increased acquisition times. Successful artifact reduction depends on the strength of the frequency encoding gradients. Newer dedicated artifact reduction sequences include view-angle-tilting and a selection of multispectral techniques including multiacquisition variable-resonance image combination (MAVRIC) and slice encoding for metal artifact correction (SEMAC). Many of these are being used in combination. The multispectral sequences acquire three-dimensional data at very narrow frequencies and use of phase encoding for spatial localization. Planar images can then be reconstructed with very little susceptibility artifact.

Test-retest reliability of automated whole body and compartmental muscle volume measurements on a wide bore 3T MR system.

PURPOSE: To measure the test-retest reproducibility of an automated system for quantifying whole body and compartmental muscle volumes using wide bore 3 T MRI. MATERIALS AND METHODS: Thirty volunteers stratified by body mass index underwent whole body 3 T MRI, two-point Dixon sequences, on two separate occasions. Water-fat separation was performed, with automated segmentation of whole body, torso, upper and lower leg volumes, and manually segmented lower leg muscle volumes. RESULTS: Mean automated total body muscle volume was 19·32 L (SD9·1) and 19·28 L (SD9·12) for first and second acquisitions (Intraclass correlation coefficient (ICC) = 1·0, 95% level of agreement -0·32-0·2 L). ICC for all automated test-retest muscle volumes were almost perfect (0·99-1·0) with 95% levels of agreement 1.8-6.6% of mean volume. Automated muscle volume measurements correlate closely with manual quantification (right lower leg: manual 1·68 L (2SD0·6) compared to automated 1·64 L (2SD 0·6), left lower leg: manual 1·69 L (2SD 0·64) compared to automated 1·63 L (SD0·61), correlation coefficients for automated and manual segmentation were 0·94-0·96). CONCLUSION: Fully automated whole body and compartmental muscle volume quantification can be achieved rapidly on a 3 T wide bore system with very low margins of error, excellent test-retest reliability and excellent correlation to manual segmentation in the lower leg. KEY POINTS: Sarcopaenia is an important reversible complication of a number of diseases. Manual quantification of muscle volume is time-consuming and expensive. Muscles can be imaged using in and out of phase MRI. Automated atlas-based segmentation can identify muscle groups. Automated muscle volume segmentation is reproducible and can replace manual measurements.

Specific food structures supress appetite through reduced gastric emptying rate.

The aim of this study was to determine the extent to which gastric layering and retention of a meal could be used to reduce appetite using the same caloric load. Liquid (control) and semi-solid (active) meals were produced with the same protein, fat, carbohydrate, and mass. These were fed to 10 volunteers on separate days in a crossover study, and subjective appetite ratings, gastric contents, and plasma cholecystokinin (CCK) were assessed over a period of 3 h. The active meal showed food boluses in the stomach persisting for ~45 min, slower emptying rates, and lower plasma CCK levels over the first hour. After the first hour, both gastric emptying rates and plasma CCK levels were similar for both systems and slightly increased compared with the unfed situation. Despite the lower plasma CCK levels for the active meal over the first hour, this meal reduced appetite more than the control meal over the 3 h of the study. For a moderately increased plasma CCK level in the fed state, appetite was correlated with the volume of gastric contents rather than gastric emptying rates or plasma CCK. This suggests that enhanced gastric retention was the key factor in decreasing appetite and was probably mediated by a combination of intestinal nutrient sensing and increased viscosity in the stomach.

Extended pathology reporting of resection specimens of colorectal liver metastases: the significance of a tumour pseudocapsule.

INTRODUCTION: The aim of this study was to analyse the influence of factors reported in the minimum histopathology dataset for colorectal liver metastases (CRLM) and other pre-operative factors compared with additional data relating to the presence of tumour pseudocapsules and necrosis on recurrence 1 year after a resection. METHODS: For a period of 14 months, extended histological reporting of CRLM specimens was performed, including the presence of pseudocapsules and necrosis in each tumour. The details of recurrence were obtained from surveillance imaging. RESULTS: In 66 patients there were 27 recurrences within 1 year. The rates were lower for patients with tumour pseudocapsules (8/27) than for patients without (19/36) (P = 0.030). Pseudocapsules were associated with a younger age (P = 0.005), nodal stage of the primary colorectal tumour (P = 0.025) and metachronous tumours (P = 0.004). In patients with synchronous disease and pseudocapsules, the recurrence rate was 2/12 compared with 13/23 patients without pseudocapsules (P = 0.026). DISCUSSION: These findings demonstrate that histological examination of resection specimens can provide significant additional prognostic information for patients after resection of CRLM, compared with clinical and radiological data. The present finding that the absence of a pseudocapsule in patients with synchronous CRLM is associated with a dramatically worse outcome may help direct patient-specific adjuvant treatment and care.

Image quality in whole-body MRI using the MY-RADS protocol in a prospective multi-centre multiple myeloma study.

BACKGROUND: The Myeloma Response Assessment and Diagnosis System (MY-RADS) guidelines establish a standardised acquisition and analysis pipeline for whole-body MRI (WB-MRI) in patients with myeloma. This is the first study to assess image quality in a multi-centre prospective trial using MY-RADS. METHODS: The cohort consisted of 121 examinations acquired across ten sites with a range of prior WB-MRI experience, three scanner manufacturers and two field strengths. Image quality was evaluated qualitatively by a radiologist and quantitatively using a semi-automated pipeline to quantify common artefacts and image quality issues. The intra- and inter-rater repeatability of qualitative and quantitative scoring was also assessed. RESULTS: Qualitative radiological scoring found that the image quality was generally good, with 94% of examinations rated as good or excellent and only one examination rated as non-diagnostic. There was a significant correlation between radiological and quantitative scoring for most measures, and intra- and inter-rater repeatability were generally good. When the quality of an overall examination was low, this was often due to low quality diffusion-weighted imaging (DWI), where signal to noise ratio (SNR), anterior thoracic signal loss and brain geometric distortion were found as significant predictors of examination quality. CONCLUSIONS: It is possible to successfully deliver a multi-centre WB-MRI study using the MY-RADS protocol involving scanners with a range of manufacturers, models and field strengths. Quantitative measures of image quality were developed and shown to be significantly correlated with radiological assessment. The SNR of DW images was identified as a significant factor affecting overall examination quality. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03188172 , Registered on 15 June 2017. CRITICAL RELEVANCE STATEMENT: Good overall image quality, assessed both qualitatively and quantitatively, can be achieved in a multi-centre whole-body MRI study using the MY-RADS guidelines. KEY POINTS: • A prospective multi-centre WB-MRI study using MY-RADS can be successfully delivered. • Quantitative image quality metrics were developed and correlated with radiological assessment. • SNR in DWI was identified as a significant predictor of quality, allowing for rapid quality adjustment.

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.

Evaluation of Acute Supplementation With the Ketone Ester (R)-3-Hydroxybutyl-(R)-3-Hydroxybutyrate (deltaG) in Healthy Volunteers by Cardiac and Skeletal Muscle 31P Magnetic Resonance Spectroscopy.

In this acute intervention study, we investigated the potential benefit of ketone supplementation in humans by studying cardiac phosphocreatine to adenosine-triphosphate ratios (PCr/ATP) and skeletal muscle PCr recovery using phosphorus magnetic resonance spectroscopy (31P-MRS) before and after ingestion of a ketone ester drink. We recruited 28 healthy individuals: 12 aged 23-70 years for cardiac 31P-MRS, and 16 aged 60-75 years for skeletal muscle 31P-MRS. Baseline and post-intervention resting cardiac and dynamic skeletal muscle 31P-MRS scans were performed in one visit, where 25 g of the ketone monoester, deltaG®, was administered after the baseline scan. Administration was timed so that post-intervention 31P-MRS would take place 30 min after deltaG® ingestion. The deltaG® ketone drink was well-tolerated by all participants. In participants who provided blood samples, post-intervention blood glucose, lactate and non-esterified fatty acid concentrations decreased significantly (-28.8%, p ≪ 0.001; -28.2%, p = 0.02; and -49.1%, p ≪ 0.001, respectively), while levels of the ketone body D-beta-hydroxybutyrate significantly increased from mean (standard deviation) 0.7 (0.3) to 4.0 (1.1) mmol/L after 30 min (p ≪ 0.001). There were no significant changes in cardiac PCr/ATP or skeletal muscle metabolic parameters between baseline and post-intervention. Acute ketone supplementation caused mild ketosis in blood, with drops in glucose, lactate, and free fatty acids; however, such changes were not associated with changes in 31P-MRS measures in the heart or in skeletal muscle. Future work may focus on the effect of longer-term ketone supplementation on tissue energetics in groups with compromised mitochondrial function.