Does hydration status influence kidney volume in autosomal dominant polycystic kidney disease?

Autosomal dominant polycystic kidney disease (ADPKD) is a progressive kidney disease where the size of the kidneys is correlated to the stage of kidney failure. Total kidney volume (TKV) is used as a prognostic marker to determine disease stage, progression, and possible effect of treatment. It has been shown that water restriction is associated with reduced kidney volume in healthy subjects. The aim of this study was to evaluate the relationship between TKV and hydration status in ADPKD patients. 40 ADPKD patients with chronic kidney disease stage 1 - 3 were randomized to either 3 hours of water restriction (n = 21) or 1 hour of water loading (n = 19; intake: 20 mL/kg). The patients had a mean age of 38 years (19 - 73) and mean plasma creatinine level of 91 (54 - 178) µmol/L. Magnetic resonance imaging of the kidneys was performed before and after intervention, and TKV was measured using the ellipsoid formula. Water restriction resulted in an insignificant 0.67% increase in TKV (median: 1.48, interquartile range (IQR): 6.1, range: -1. - 4.5). Water loading resulted in an insignificant 2.67% increase in TKV (median: 3.18, IQR: 11.4, range: -3.6 - 7.8). Interestingly, a 7.09% increase in right-kidney volume was found after water loading (median: 5.58, IQR: 9.4 range: 1.9 - 11.3, p < 0.05), whereas the left-kidney volume showed an insignificant decrease of 0.18% after water loading (median: -1.65, IQR: 18.0, range: -12.5 - 5.5). We found in ADPKD patients that neither short-term water restriction nor acute water loading had significant effects, suggesting that the use of TKV for disease staging is independent of hydration level in these patients.

Pelvic capacity in pregnant women, identified using magnetic resonance imaging.

INTRODUCTION: Maternal pelvic capacity plays a major role during childbirth because the passage of the fetus through the bony birth canal enables vaginal birth. Maternal birthing position may influence pelvic capacity because upright positions optimize capacity, possibly due to free movement of the pelvic joints. Herein, pelvic capacity was assessed by comparing changes in pelvic dimensions across pregnancy and in three birthing positions. MATERIAL AND METHODS: This diagnostic imaging study of 50 pregnant women was conducted at Aarhus University Hospital, Denmark. Pelvic measurements were obtained with 1.5 T magnetic resonance pelvimetry during gestational weeks 20 and 32, in three birthing positions: kneeling squat, semi-lithotomy and supine. Pelvic capacity was compared between gestational weeks and positions. RESULTS: In all three positions there is an overall increase in pelvic capacity from gestational week 20-32 at both the pelvic inlet and outlet. Comparing pelvic capacity at gestational week 32 between the semi-lithotomy and supine positions revealed that the pelvic inlet was larger in the supine position, whereas the mean pelvic outlet was 0.2 cm (p < 0.001) larger in the semi-lithotomy position. Likewise, the pelvic inlet was larger in the supine than in the kneeling squat position. Shifting from supine to kneeling squat position increased the midplane and pelvic outlet dimensions by up to 1 cm (p < 0.001). CONCLUSIONS: The finding herein of an increased pelvic capacity as the pregnancy progresses is novel. Further, the results indicate that the supine position is optimal for increasing pelvic inlet size, whereas the semi-lithotomy and kneeling squat positions are optimal for increasing mid- and outlet-pelvic capacities.

Preoperative planning of renal transplantation: a comparison of non-contrast-enhanced ultrasonography, computed tomography, and magnetic resonance angiography with observations from surgery.

BACKGROUND: Many candidates for kidney transplantation need to undergo vessel examination before the transplantation procedure. PURPOSE: To identify the optimal preoperative modality for the examination of vessel status without the use of contrast agents in kidney transplant candidates. MATERIAL AND METHODS: Fifty-three consecutive patients were examined and 31 patients were transplanted. Ultrasonography (US), non-contrast-enhanced computed tomography (NCCT), and non-contrast-enhanced magnetic resonance angiography (NCMRA) were compared using inspection during kidney transplantation (TX) as a reference standard. The sensitivity and specificity to severe arteriosclerotic changes and the accuracy were calculated. Kappa statistics were used to assess the agreement between TX and the different examination modalities, and McNemar's test was used to test for significant differences. RESULTS: US had higher sensitivity (1.0) and better agreement with observations from surgery (k = 0.89) than both NCCT (sensitivity = 0.60; k = 0.72) and NCMRA (sensitivity = 0.20; k = 0.30). No significant difference was found between TX and US (P = 0.3173) or TX and NCCT (P = 0.1573), but there was a significant difference between TX and NCMRA (P = 0.0455). US was inconclusive in 20% of cases, and the internal iliac artery could not be visualized in 69% of cases. CONCLUSION: Either US or NCCT can be used as the preferred preoperative imaging modality to examine vessel status before kidney transplantation, but a combination of the two is preferable. NCMRA should not be used as the sole imaging modality for preoperative imaging before kidney transplantation because of its low sensitivity in detecting severe arteriosclerotic disease without the presence of stenosis.

Effects of neuromuscular control and strengthening exercises on MRI-measured thigh tissue composition and muscle properties in people with knee osteoarthritis - an exploratory secondary analysis from a randomized controlled trial.

OBJECTIVE: To investigate the effects of adding strength training to neuromuscular control exercises on thigh tissue composition and muscle properties in people with radiographic-symptomatic knee osteoarthritis (KOA). METHODS: In this exploratory secondary analysis of a randomized controlled trial, using a complete-case approach, participants performed 12 weeks of twice-weekly neuromuscular control exercise and patient education (NEMEX, n = 34) or NEMEX plus quadriceps strength training (NEMEX+ST, n = 29). Outcomes were MRI-measured inter- and intramuscular adipose tissue (InterMAT, IntraMAT), quadriceps muscle cross-sectional area (CSA), knee-extensor strength, specific strength (strength/lean CSA) and 30 s chair-stands. Between-group effects were compared using a mixed model analysis of variance. RESULTS: At 12 weeks, responses to NEMEX+ST overlapped with NEMEX for all outcomes. Both groups reduced InterMAT (NEMEX+ST=25 %, NEMEX=21 %); between-group difference: 0.8cm2 (95 % CI: -0.1, 1.7). NEMEX+ST decreased IntraMAT (2 %) and NEMEX increased IntraMAT (4 %); between-group difference 0.1 %-points (-0.3, 0.5). Both groups increased quadriceps CSA and lean CSA (CSA minus IntraMAT), improved knee-extensor strength and specific strength, and improved chair-stand performance with a trend towards greater effects in NEMEX+ST. CONCLUSION: Adding strength training to 12 weeks of neuromuscular control exercises provided largely similar effects to neuromuscular control exercises alone in decreasing InterMAT and IntraMAT, in improving knee-extensor strength, CSA and in improving performance-based function in KOA persons, with a trend towards greater effects with additional strength training. Notably, both groups substantially reduced InterMAT and improved specific strength (an index of muscle quality). Our hypothesis-generating work warrants exploration of the roles played by InterMAT and IntraMAT in exercise effects in KOA.

An Evaluation of Image Acquisition Techniques, Radiographic Practice, and Technical Quality in Neonatal Chest Radiography.

BACKGROUND: Neonatal chest radiography is a frequently performed diagnostic examination, particularly in preterm infants where anatomical and/or biochemical immaturity impacts on respiratory function. However, the quality of neonatal radiographic images has been criticized internationally and a prevailing concern has been that radiographers (radiologic technologists) fail to appreciate the unique nature of neonatal and infant anatomical proportions. The aim of this study was to undertake a retrospective evaluation of neonatal chest radiography image acquisition techniques against key technical criteria. METHODS: One hundred neonatal chest radiographs, randomly selected from those acquired in 2014, were retrospectively evaluated. Inclusion criteria for radiograph were as follows: anterior-posterior supine; within 30 days of birth; and with all preprocessed collimation boundaries visible. Image evaluation was systematically undertaken using an image assessment tool. To test for statistical significance, Student's t-test, χ2 test, and logistic regression were undertaken. RESULTS: Only 47% of the radiographs were considered straight in both upper and lower thoraces. The cranial collimation border extended beyond the upper border of the third cervical vertebra in 30% of cases, and the caudal border extended below the lower border of the first lumbar vertebra in 20% of cases, suggesting high possibility of neonatal overirradiation. Upper thorax rotation was significantly associated with head position (χ2 = 10.907; P < .001) as has been stated in many published textbooks internationally, but arm position had no apparent influence on rotation of the upper thorax (χ2 = 5.1260; P = .275). Birth weight was associated with accurate midline centering of central ray (logistic regression; OR = 1.0005; P = .009; CI, 1.00139-1.000957) with greater accuracy observed in images of neonates with higher birth weight. CONCLUSION: This study has highlighted areas for neonatal chest radiography improvement. Importantly, the findings bring into question commonly advocated radiographic techniques relating to arm positioning and assessment of rotation while confirming the importance of other technical factors. These findings begin the work toward developing the evidence base to underpin neonatal chest radiograph acquisition, but further prospective work and multicenter/multinational data comparison are required to confirm the findings.

Noncontrast-Enhanced Magnetic Resonance Versus Computed Tomography Angiography in Preoperative Evaluation of Potential Living Renal Donors.

RATIONALE AND OBJECTIVES: Living renal donors undergo an extensive examination program. These examinations should be as safe, gentle, and patient friendly as possible. To compare computed tomography angiography (CTA) and an extensive magnetic resonance imaging (MRI) protocol without contrast agents to observations from nephrectomy in living renal donors and to evaluate whether noncontrast-enhanced MRI can replace CTA for vessel assessment in living renal donors. MATERIAL AND METHODS: CTA and MRI results were compared to observations from nephrectomy, which served as the reference standard. Fifty-one potential kidney donors underwent imaging, and 31 donated a kidney. Comparisons in sensitivity, specificity, and accuracy were made with respect to the number of arteries, early branching, and the number of veins. Agreement was assessed using Cohen's kappa. The exact McNemar's test was used to test for statistically significant differences. RESULTS: In the assessment of more than one renal artery, the sensitivity and specificity of MRI and CTA were high and in perfect agreement compared to observations from surgery. The results for both MRI and CTA were as follows: (sensitivity 100%/specificity100%/accuracy 100%/Kappa = 1/P = 1). When comparing the ability to test for early branching we found, MRI: (sensitivity 33%/specificity 100%/accuracy 87%/Kappa = 0.45/P = 1) and CTA: (sensitivity 50%/specificity 100%/accuracy 90%/Kappa = 0.62/P = 1). When used to depict supernumerary veins, we found MRI: (sensitivity60%/specifivity100%/accuracy 93%/Kappa = 0.72/P = 1), whereas CTA showed: (sensitivity 40%/specificity 96%/accuracy 87% Kappa = 0.43/P = 1). CONCLUSIONS: In conclusion, an optimized MRI protocol that includes noncontrast-enhanced magnetic resonance angiography can be substituted for CTA for preoperative assessment of the renal vessels before living donor nephrectomy.

Non-contrast-enhanced magnetic resonance angiography: techniques and applications.

Non-contrast-enhanced magnetic resonance angiography has gained renewed interest since the discovery of the association between gadolinium-based contrast agents and nephrogenic systemic fibrosis. The following article is an overview of the different magnetic resonance angiography sequences, the technical possibilities and new developments. Clinical options and recent advancements will be highlighted, and recommendations for non-contrast-enhanced magnetic resonance angiography techniques in different anatomical regions will be given. Furthermore, the authors seek to predict the future of non-contrast-enhanced magnetic resonance angiography, with special focus on patients at risk.

Inferring origin of vascular supply from tracer arrival timing patterns using bolus tracking MRI.

PURPOSE: To investigate the potential of novel postprocessing and visualization techniques to distinguish presence of collateral flow using Bolus Tracking MRI. Collateral blood supply is believed to be of paramount importance in acute stroke, yet clinical evaluation is challenging as the gold standard digital subtraction angiography is often not feasible in the acute scenario. MATERIALS AND METHODS: In principle, bolus arrival delay data contains information about the route of blood supply into tissue and hereby presence of collateral flow patterns. We first examined the potential of current clinical bolus tracking protocols to accurately characterize bolus arrival delay. Using the simulation results, we analyzed bolus tracking data from one normal volunteer and one acute stroke patient. RESULTS: The bolus arrival patterns in the volunteer and in the normal hemisphere of the patient were found to be qualitatively similar and in good agreement with physiology. The bolus was seen to spread from the larger arteries toward the periphery. The stroke hemisphere in the patient indicated a retrograde direction of flow on the cortical mantle consistent with leptomeningeal vessels. CONCLUSION: Bolus tracking MRI can likely be used to distinguish collateral flow patterns from normal flow patterns.