Prospective Volunteer Study Research Articles

Development and Evaluation of Deep Learning-Accelerated Single-Breath-Hold Abdominal HASTE at 3 T Using Variable Refocusing Flip Angles.

Deep learning (DL) reconstruction enables substantial acceleration of image acquisition while maintaining diagnostic image quality. The aims of this study were to overcome the drawback of specific absorption rate (SAR)-related limitations at 3 T and to develop a DL-accelerated single-breath-hold half-Fourier acquisition single-shot turbo spin echo (HASTE) sequence for 2-dimesional T2-weighted fat-suppressed magnetic resonance imaging of the abdomen at 3 T using a variable flip angle (FA) evolution for the refocusing radiofrequency pulses, as well as to evaluate its feasibility and image quality in comparison to state-of-the-art T2-weighted fat-suppressed imaging technique (BLADE). First, a suitable FA evolution with low cardiac motion-related signal loss (CRSL) and low SAR was determined through a prospective volunteer study with 11 participants. Image quality and diagnostic confidence with 5 different FA evolutions of a HASTEDL were assessed to identify the most suitable FA evolution. Second, the identified FA evolution was implemented clinically and evaluated in 51 patients undergoing a clinically indicated liver magnetic resonance imaging at 3 T. Two radiologists assessed the HASTEDL and standard sequences regarding overall image quality, noise, contrast, sharpness, artifacts, CRSL, and diagnostic confidence using a Likert scale ranging from 1 to 4, with 4 being the best. Comparative analyses were conducted to assess the differences between HASTEDL (acquisition time, 21 seconds; single breath-hold) and the routinely used T2-weighted BLADE sequence (acquisition time, 4 minutes; respiratory triggering). From the volunteer study, the FA evolution characterized by the control points 130-90-110-130 degrees (HASTEDL) was identified as optimal among the 5 evolutions evaluated and was implemented in our clinical protocol. In all 51 patients, HASTEDL was successfully acquired at 3 T and showed excellent image quality (median, 4; interquartile range, 3-4). Although BLADE was rated significantly higher for overall image quality, noise, contrast, sharpness, artifacts, CRSL, and diagnostic confidence than HASTEDL, no differences were found concerning the number (n = 102) and measured diameter of the detected hepatic lesions between the 2 sequences BLADE and HASTEDL. The proposed single-breath-hold abdominal HASTEDL with variable refocusing FAs is feasible at 3 T within SAR limits and yields high image quality and diagnostic confidence as compared with a standard T2-weighted acquisition technique, at a 10th of the acquisition time.

Extracranial Soft-Tissue Tumors: Repeatability of Apparent Diffusion Coefficient Estimates from Diffusion-weighted MR Imaging.

Purpose To assess the repeatability of apparent diffusion coefficient (ADC) estimates in extracranial soft-tissue diffusion-weighted magnetic resonance imaging across a wide range of imaging protocols and patient populations. Materials and Methods Nine prospective patient studies and one prospective volunteer study, performed between 2006 and 2016 with research ethics committee approval and written informed consent from each subject, were included in this single-institution study. A total of 141 tumors and healthy organs were imaged twice (interval between repeated examinations, 45 minutes to 10 days, depending the on study) to assess the repeatability of median and mean ADC estimates. The Levene test was used to determine whether ADC repeatability differed between studies. The Pearson linear correlation coefficient was used to assess correlation between coefficient of variation (CoV) and the year the study started, study size, and volumes of tumors and healthy organs. The repeatability of ADC estimates from small, medium, and large tumors and healthy organs was assessed irrespective of study, and the Levene test was used to determine whether ADC repeatability differed between these groups. Results CoV aggregated across all studies was 4.1% (range for each study, 1.7%-6.5%). No correlation was observed between CoV and the year the study started or study size. CoV was weakly correlated with volume (r = -0.5, P = .1). Repeatability was significantly different between small, medium, and large tumors (P < .05), with the lowest CoV (2.6%) for large tumors. There was a significant difference in repeatability between studies-a difference that did not persist after the study with the largest tumors was excluded. Conclusion ADC is a robust imaging metric with excellent repeatability in extracranial soft tissues across a wide range of tumor sites, sizes, patient populations, and imaging protocol variations. Online supplemental material is available for this article.

Asymmetric Thermal Response of Human Feet to Hopping Detected by Digital Infrared Imaging

Aims: The purpose of this study was to evaluate the effect of asymmetric exercise, hopping, on skin temperature at the foot and ankle subregions by infrared thermography. Study Design: Prospective volunteer study. Place and Duration of Study: Department of Orthopaedic Surgery and Department of Radiology, Chung-Ang University Hospital, between June 2013 and March 2014. Methodology: Ten healthy male volunteers hopped with their dominant limb 1,000 times or for 15 min. Thermography was taken by using an infrared imaging device at 24°C. Each volunteer had four thermographic images of the dorsum, plantar and calf views of both limbs before hopping, and at 5, 20 and 30 min after hopping. Temperatures were measured at the dorsum of the foot (subregion 1), lower tibialis anterior (subregion 2), medial plantar (subregion 3), lateral plantar (subregion 4), calf (subregion 5) and Achilles tendon (subregion 6). Original Research Article Kwak et al.; BJMMR, 6(11): 1078-1085, 2015; Article no.BJMMR.2015.285 1079 Results: Hopping changed the temperature with different patterns depending on 12 subregions after hopping. At 5 min, except for subregion 3 and 4 of the hopping limb, the other ten subregions showed decreases in skin temperature. Temperatures of all subregions of the hopped limb were higher than that of non-hopped limb ranging from the lowest, 0.54°C atsubregion 1 at 5 min, to the highest, 1.18°C atsubregion 6 at 5 min. Each subregion of the hopped limb was 0.5°C or higher than that of non-hopped limb from 5 till 30 minutes after exercise (P < 0.05). Conclusion: Heat changes in the foot and ankle by exercise can be imaged and evaluated. After asymmetric exercise, hopping, the subregions of the foot and ankle respond differently. For proper image interpretation, knowing whether asymmetric exercise occurred in the limb of interest is important before image acquisition.

Use of the temporal median and trimmed mean mitigates effects of respiratory motion in multiple-acquisition abdominal diffusion imaging

Respiratory motion commonly confounds abdominal diffusion-weighted magnetic resonance imaging, where averaging of successive samples at different parts of the respiratory cycle, performed in the scanner, manifests the motion as blurring of tissue boundaries and structural features and can introduce bias into calculated diffusion metrics. Storing multiple averages separately allows processing using metrics other than the mean; in this prospective volunteer study, median and trimmed mean values of signal intensity for each voxel over repeated averages and diffusion-weighting directions are shown to give images with sharper tissue boundaries and structural features for moving tissues, while not compromising non-moving structures. Expert visual scoring of derived diffusion maps is significantly higher for the median than for the mean, with modest improvement from the trimmed mean. Diffusion metrics derived from mono- and bi-exponential diffusion models are comparable for non-moving structures, demonstrating a lack of introduced bias from using the median. The use of the median is a simple and computationally inexpensive alternative to complex and expensive registration algorithms, requiring only additional data storage (and no additional scanning time) while returning visually superior images that will facilitate the appropriate placement of regions-of-interest when analysing abdominal diffusion-weighted magnetic resonance images, for assessment of disease characteristics and treatment response.

Contribution of serum ethanol concentration to the osmol gap: a prospective volunteer study

Contribution of serum ethanol concentration to the osmol gap: a prospective volunteer study

Contribution of serum ethanol concentration to the osmol gap: a prospective volunteer study

Background. The contribution of ethanol ([EtOH]) to the osmol gap (OG) is commonly described by the formula [EtOH (mg/dL)]/k, where k is assumed to be 4.6 (one-tenth of its molecular weight) if ethanol behaves ideally in solution. However, several studies on convenience samples of patients suggest that ethanol does not behave ideally and that k may be significantly different from this ideal constant. Objectives. To determine prospectively the relationship between serum ethanol concentration and total serum osmolality in a group of healthy volunteers. Methods. Experimental subjects ingested 20 mL of 100% ethanol diluted in sugar-free soda at a rate of one drink every 10 min, up to a maximum of seven drinks. Control subjects ingested 20 mL of water diluted in sugar-free soda at the same rate. Blood samples were obtained at baseline and then at every 20 min for 180 min to measure serum [EtOH] concentration, electrolytes, glucose, and osmolality (via freezing-point depression). The OG was calculated by subtracting predicted osmolality from measured osmolality. The OG was then divided by [EtOH] to determine the coefficient of ethanol's contribution to total serum osmolality. Results. A total of 10 volunteers (five men and five women; mean age, 38.8 years, and range, 28–49 years) participated in and completed the study. Eight (four male and four female) were in the experimental group, and two (one male and one female) were in the control group. Mean peak [EtOH] was 229 mg/dL (median, 223.5 mg/dL; IQR, 171–273 mg/dL) and a linear relationship between [EtOH] and OG (Pearson coefficient of 0.98) was found. Using covariate correction for each subject's baseline OG, k was calculated to be 4.25 (95% CI, 4.13–4.38) averaged over all participants. Conclusions. In this volunteer study, the coefficient describing the contribution of ethanol to serum osmolality (k) was found to be 4.25. This indicates that ethanol contributes more to total serum osmolality than would be predicted for an ideal solute.

A Comparison of Ultrasound-Guided and Landmark-Based Approaches to Saphenous Nerve Blockade

Blockade of the saphenous nerve is often used for surgeries below the knee. Depending on the approach, success rates vary widely ranging from 33% to 88%. In this prospective volunteer study, we compared 2 ultrasound-guided techniques, the modified vastus medialis and perifemoral saphenous nerve block with a below the knee field block. Twenty volunteer adults, in a single-blinded, crossover, prospective trial underwent 3 different saphenous nerve blocks. The primary end point of block success was loss of sensation in the distal two-thirds distribution of the saphenous nerve. Secondary variables included time to perform the block, time to sensory loss, pain during block, and motor weakness. Compared with the below the knee field block success rate (30%), both the modified vastus medialis and perifemoral techniques had significantly higher success rates (80%, difference 50% with confidence interval [CI], 23%-77%, P = 0.009, and 100%, difference 70% with CI, 41%-91%, P < 0.001, respectively). However, the difference when comparing the perifemoral ultrasound technique against the modified vastus medialis ultrasound technique did not show significance (difference 20% with CI, -7% to 49%, P = 0.125). Also, no statistical differences were found with the other variables measured, except the perifemoral technique showed faster block performance times than below the knee field block (P = 0.007). In our prospective study, we have demonstrated that ultrasound-guided above the knee saphenous nerve blocks have higher success rates than a below the knee field block and are easily performed in a short amount of time.

High-Resolution Ultrasound Accurately Identifies the Medial Antebrachial Cutaneous Nerve at the Midarm Level

The present prospective volunteer study was designed to describe a technique for ultrasound identification of the medial antebrachial cutaneous nerve (MACN) and a technique for ultrasound-guided blockade of this sensory nerve of the upper limb. Twenty male volunteers were included in this study. After cross-sectional ultrasound identification of the MACN at the upper arm, where it is closely adjacent to the basilic vein, a selective blockade via an in-plane needle guidance technique was performed with 0.3 mL of mepivacaine 1.5% under direct ultrasound visualization. Sensory loss to pinprick at the upper extremity was evaluated and compared with the contralateral side. Constant ultrasound visualization of the MACN adjacent to the basilic vein at the upper arm level was possible in all cases. Blockade of the MACN under direct visualization was associated with a 100% success rate. The results of this investigation enable selective blockade of the MACN via ultrasound. Moreover, our data provide insight regarding the specific anatomic course and the integrity of this sensory nerve, which could be used for plastic and reconstructive surgical indications and for diagnosis of nerve injury.