Automatic labeling of portal and hepatic veins from MR images prior to liver transplantation

Purpose

Living donated liver transplantation is an important task since a person (healthy donor) donates some part of her/his liver to a person in this surgery operation. The success of this operation mainly depends on the sufficiency of vessels and volume of the liver. Accurate labeling of portal and hepatic veins of donors reduces the incidence of complications during and after transplantation. Therefore, prior to the hepatic surgery, automatic analysis and labeling of vasculature structures in the liver are vital to see whether liver is suitable or not for transplantation. However, automatic labeling of veins in the liver is challenging because of partial volume effects, noise and image resolution, which causes wrong connections between vessels. The goal of this paper is to propose an automatic labeling approach for vessels.

Methods

The proposed automated labeling method is based on gray-level values in the MR images and anatomical information. In this work, detection and segmentation of vascular structures in the liver is performed automatically with clustering-based segmentation and refinement stages.

Results

The accuracy of the automatic labeling approach is 85 %. Required processing time for the proposed method (average 6 s) is shorter than manual approach (average 295 s) for labeling of hepatic and portal veins from segmented vessels.

Conclusion

The proposed approach is efficient in terms of both computational cost and accuracy of labeling and segmentation of hepatic and portal veins.

     

The interactive electrode localization utility: software for automatic sorting and labeling of intracranial subdural electrodes

Purpose

Existing methods for sorting, labeling, registering, and across-subject localization of electrodes in intracranial encephalography (iEEG) may involve laborious work requiring manual inspection of radiological images.

Methods

We describe a new open-source software package, the interactive electrode localization utility which presents a full pipeline for the registration, localization, and labeling of iEEG electrodes from CT and MR images. In addition, we describe a method to automatically sort and label electrodes from subdural grids of known geometry.

Results

We validated our software against manual inspection methods in twelve subjects undergoing iEEG for medically intractable epilepsy. Our algorithm for sorting and labeling performed correct identification on 96% of the electrodes.

Conclusions

The sorting and labeling methods we describe offer nearly perfect performance and the software package we have distributed may simplify the process of registering, sorting, labeling, and localizing subdural iEEG grid electrodes by manual inspection.

     

A geometric method for the detection and correction of segmentation leaks of anatomical structures in volumetric medical images

Purpose

Patient-specific models of anatomical structures and pathologies generated from volumetric medical images play an increasingly central role in many aspects of patient care. A key task in generating these models is the segmentation of anatomical structures and pathologies of interest. Although numerous segmentation methods are available, they often produce erroneous delineations that require time-consuming modifications.

Methods

   We present a new geometry-based algorithm for the reliable detection and correction of segmentation errors in volumetric medical images. The method is applicable to anatomical structures consisting of a few 3D star-shaped components. First, it detects segmentation errors by casting rays from the initial segmentation interior to its outer surface. It then classifies the segmentation surface into correct and erroneous regions by minimizing an energy functional that incorporates first- and second-order properties of the rays lengths. Finally, it corrects the segmentation errors by computing new locations for the erroneous surface points by Laplace deformation so that the new surface has maximum smoothness with respect to the rays-length gradient magnitude.

Results

   Our evaluation on initial segmentations of 16 abdominal aortic aneurysm and 12 lung tumors in CT scans obtained by both adaptive region-growing and active contours level-set segmentation improved the volumetric overlap error by 66 and 70.5 % respectively, with respect to the ground-truth.

Conclusions

   The advantages of our method are that it is independent of the initial segmentation algorithm that covers a variety of anatomical structures and pathologies, that it does not require a shape prior, and that it requires minimal user interaction.

     

Clinical application of navigator-gated three-dimensional balanced turbo-field-echo magnetic resonance cholangiopancreatography at 3 T: prospective intraindividual comparison with 1.5 T

Objective

To evaluate and compare the clinical utility of balanced turbo-field-echo (BTFE) magnetic resonance cholangiopancreatography (MRCP) sequences obtained at 3 and 1.5 T.

Methods

We acquired three-dimensional (3D) BTFE MRCP scans with a navigator-gated technique at 3 T on a different day after 1.5 T in 39 consecutive patients. Two radiologists independently rated the image quality and visibility of anatomical structures (right and left hepatic duct, cystic duct, gallbladder, common bile duct, and main pancreatic duct) using a four-point scale. For quantitative analysis, the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and acquisition time were evaluated.

Results

All visual scores tended to be higher for 1.5 T than 3 T images. There was a significant difference in the image quality and the depiction of the main pancreatic duct (p < 0.01). The image acquisition time was significantly shorter for 3 T than 1.5 T (199.3 ± 40.1 vs. 264.0 ± 86.5 s, p < 0.01). There was no significant difference in SNR and CNR.

Conclusions

3D-BTFE MRCP scans acquired at 3 T were of sufficient image quality with respect to the biliary tree. SNR and CNR were comparable on 3 and 1.5 T scans, although the acquisition time was significantly shorter with the 3 T scanner.

     

In Vivo HER2-Targeted Magnetic Resonance Tumor Imaging Using Iron Oxide Nanoparticles Conjugated with Anti-HER2 Fragment Antibody

Purpose

The feasibility of iron oxide nanoparticles (IONPs) conjugated with anti-epidermal growth factor receptor 2 (HER2) single-chain antibody (scFv-IONPs) as novel HER2-targeted magnetic resonance (MR) contrast agents was investigated.

Procedures

The scFv-IONPs were prepared and identified. For in vitro MRI, NCI-N87 (HER2 high expression) and SUIT2 (low expression) cells were incubated with scFv-IONPs. For in vivo MRI, NCI-N87 and SUIT2 tumor-bearing mice were intravenously injected with scFv-IONPs and imaged before and 24 h post-injection.

Results

The scFv-IONPs demonstrated high transverse relaxivity (296.3 s^?1 mM^?1) and affinity toward HER2 (K_D?=?11.7 nM). In the in vitro MRI, NCI-N87 cells treated with scFv-IONPs exhibited significant MR signal reduction (44.6 %) than SUIT2 cells (6.8 %). In the in vivo MRI, decrease of MR signals in NCI-N87 tumors (19.3 %) was more notable than that in SUIT2 tumors (6.2 %).

Conclusions

The scFv-IONPs enabled HER2-specific tumor MR imaging, suggesting the potential of scFv-IONPs as a robust HER2-targeted MR contrast agent.

     

Optimization of a Labeling and Kit Preparation Method for Ga-68 Labeled DOTATATE,Using Cation Exchange Resin Purified Ga-68 Eluates Obtained from a Tin Dioxide <Superscript>68</Superscript>Ge/<Superscript>68</Superscript>Ga Generator

Purpose

The aim of this study was to optimize a radiolabeling method using cationic processed Ga-68 eluates from a SnO₂-based ⁶⁸Ge/⁶⁸Ga generator, followed by the development of DOTA-Tyr³-Thre⁸-octreotide (DOTATATE) kits.

Procedures

Diluted generator eluates were adsorbed on a SCX resin and desorbed with acidified 5 M NaCl solution. Optimized labeling conditions were determined by variation of pH, using 35 μg DOTATATE and sodium acetate buffer. DOTATATE kits were developed based on optimized radiolabeling conditions, were labeled, and evaluated.

Results

Optimized labeling conditions resulted in a radiolabeling efficiency of around 99 % and radiochemical yield of almost 85 %. Different kit preparation methods did not significantly influence the radiolabeling results. Kits were found to be stable over 3 months.

Conclusion

A labeling method using SCX-processed Ga-68 eluates was optimized. DOTATATE kits specifically for these SCX-processed Ga-68 eluates were successfully formulated. A post-labeling Sep-Pak C18 purification should be optional.

     

Comparison of hepatocellular carcinoma conspicuity on hepatobiliary phase images with gadoxetate disodium vs. delayed phase images with extracellular cellular contrast agent

Objective

To compare the conspicuity of hepatocellular carcinoma (HCC) on hepatobiliary phase of gadoxetate disodium-enhanced vs. delayed phase of gadodiamide-enhanced MR images, relative to liver function.

Methods and materials

We retrospectively identified 86 patients with newly diagnosed HCC between 2010 and 2013 and recorded the severity of liver disease by Child-Pugh class (CPC). 38 patients had gadodiamide-enhanced 5-min delayed and 48 had gadoxetate disodium-enhanced 20-min delayed hepatobiliary MR images. The conspicuity of 86 HCCs (mean size, 2.7 cm) was graded visually on a 3-point scale and quantified by liver-to-tumor contrast ratios (LTC). The relative liver parenchymal enhancement (RPE) was measured. For different CPCs, we compared the conspicuity of HCC and RPE between gadodiamide and gadoxetate.

Results

In patients with CPC A, the visual conspicuity and LTC of the 27 HCCs imaged with gadodiamide were significantly lower than those of the 38 HCCs with gadoxetate (P < 0.01, <0.01, respectively). RPE was lower in gadodiamide scans than gadoxetate scans (P < 0.01). Conversely, in patients with CPC B and C, HCCs appeared more frequently as definite hypointensity when imaged with gadodiamide (72.7%, 8/11) than gadoxetate (20%, 2/10, P = 0.03). LTC (mean 18.1 vs. 7.5, P = 0.04) and RPE (mean 75.5 vs. 45.4, P = 0.04) was significantly higher in the gadodiamide than gadoxetate scans.

Conclusion

In patients with compromised liver function, hypointensity of HCC is more conspicuous in the gadodiamide delayed phase than the gadoxetate hepatobiliary phase. This likely reflects the high extracellular accumulation of gadodiamide and poor hepatocyte uptake of gadoxetate in patients with compromised liver function.

     

How to Provide Gadolinium-Free PET/MR Cancer Staging of Children and Young Adults in Less than 1 h: the Stanford Approach

Purpose

To provide clinically useful gadolinium-free whole-body cancer staging of children and young adults with integrated positron emission tomography/magnetic resonance (PET/MR) imaging in less than 1 h.

Procedures

In this prospective clinical trial, 20 children and young adults (11–30 years old, 6 male, 14 female) with solid tumors underwent 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) PET/MR on a 3T PET/MR scanner after intravenous injection of ferumoxytol (5 mg Fe/kg) and [¹⁸F]FDG (2–3 MBq/kg). Time needed for patient preparation, PET/MR image acquisition, and data processing was compared before (n = 5) and after (n = 15) time-saving interventions, using a Wilcoxon test. The ferumoxytol-enhanced PET/MR images were compared with clinical standard staging tests regarding radiation exposure and tumor staging results, using Fisher’s exact tests.

Results

Tailored workflows significantly reduced scan times from 36 to 24 min for head to mid thigh scans (p < 0.001). These streamlined PET/MR scans were obtained with significantly reduced radiation exposure (mean 3.4 mSv) compared to PET/CT with diagnostic CT (mean 13.1 mSv; p = 0.003). Using the iron supplement ferumoxytol “off label” as an MR contrast agent avoided gadolinium chelate administration. The ferumoxytol-enhanced PET/MR scans provided equal or superior tumor staging results compared to clinical standard tests in 17 out of 20 patients. Compared to PET/CT, PET/MR had comparable detection rates for pulmonary nodules with diameters of equal or greater than 5 mm (94 vs. 100 %), yet detected significantly fewer nodules with diameters of less than 5 mm (20 vs 100 %) (p = 0.03). [¹⁸F]FDG-avid nodules were detected with slightly higher sensitivity on the PET of the PET/MR compared to the PET of the PET/CT (59 vs 49 %).

Conclusion

Our streamlined ferumoxytol-enhanced PET/MR protocol provided cancer staging of children and young adults in less than 1 h with equivalent or superior clinical information compared to clinical standard staging tests. The detection of small pulmonary nodules with PET/MR needs to be improved.

     

Human Radiation Dosimetry of [<Superscript>18</Superscript>F]AV-1451(T807) to Detect Tau Pathology

Purpose

[¹⁸F]AV-1451 is a positron emission tomography (PET) radioligand for detecting paired helical filament tau. Our aim was to estimate the radiation dose of [¹⁸F]AV-1451 in humans.

Procedures

Whole-body PET scans were acquired for six healthy volunteers (three male, three female) for 128 min after injection of [¹⁸F]AV-1451 (268?±?31 MBq). Radiation doses were estimated using the OLINDA/EXM software.

Results

The estimated organ doses ranged from 7.81 to 81.2 μSv/MBq. The critical organ for radiation burden was the liver. Radiation doses to the reproductive and blood-forming organs were 14.15, 8.43, and 18.35 μSv/MBq for the ovaries, testes, and red marrow, respectively. The mean effective dose was 22.47?±?3.59 μSv/MBq.

Conclusions

A standard single injection of 185 MBq (5 mCi) results in an effective dose of 4.7 mSv in a healthy subject. Therefore, [¹⁸F]AV-1451 could be used in multiple PET scans of the same subject per year.

     

Characterization of “γ-Eye”: a Low-Cost Benchtop Mouse-Sized Gamma Camera for Dynamic and Static Imaging Studies

Purpose

Several preclinical imaging systems are commercially available, but their purchase and maintenance costs make them unaffordable for the majority of small- and medium-sized groups. Taking into account the needs of average users, we developed “γ-eye”, a mouse-sized, benchtop γ-camera suitable for in vivo scintigraphic imaging.

Procedures

The γ-eye is based on two position-sensitive photomultiplier tubes, coupled to a CsI(Na) pixelated scintillator and a low-energy lead collimator with parallel hexagonal holes.

Results

The spatial resolution of the system is 2 mm at 0 mm. The energy resolution is 26 % at 140 keV and the maximum recorded sensitivity 210 cps/MBq. The system was evaluated in a proof-of-concept animal study, using three different clinical Tc-99m-labeled radiopharmaceuticals. Phantom and animal studies demonstrate its ability to provide semiquantitative results even for short scans.

Conclusions

Systems’ performance, dimensions, and cost make γ-eye a unique solution for efficient whole-body mouse nuclear imaging.

     

Mesalazine Modified-Release Tablet in the Treatment of Ulcerative Colitis in the Active Phase: A Chinese,Multicenter, Single-Blind,Randomized Controlled Study

Introduction

This study compared the efficacy and safety of two mesalazine formulations in the treatment of Chinese patients with mildly to moderately active ulcerative colitis (UC).

Methods

In this multicenter, single-blind, randomized controlled study of 251 patients with active UC conducted from November 2010 to January 2012, subjects were randomized to treatment with mesalazine modified-release tablets (MR group, n = 123) or enteric-coated tablets (EC group, n = 128) at 800 mg three-times daily for 8 weeks. The primary efficacy measure was the decrease in UC Disease Activity Index (UCDAI) at final evaluation. If the 95% confidence interval (CI) lower limit of the difference of the decrease in UCDAI between groups was over ?1.0, mesalazine modified-release tablets were considered non-inferior to mesalazine enteric-coated tablets. The change in UCDAI in patients with mild and moderate (UCDAI 3–5 and 6–8 at enrollment, respectively) UC was analyzed. Secondary efficacy measures were remission and efficacy rates. Incidences of adverse drug reactions (ADRs) were calculated.

Results

The decreases in UCDAI at final evaluation were 2.84 and 2.56 in the MR and EC groups, respectively, with a difference of 0.27 between groups (95% CI ?0.34, 0.88). The remission rates were 48.33% (58/120) and 55.65% (69/124), and the efficacy rates were 63.33% (76/120) and 66.94% (83/124) in the MR and EC groups, respectively (all P > 0.05). In patients with mild UC, the decreases in UCDAI were 2.16 and 2.05 in the MR and EC groups, respectively, while in patients with moderate UC they were 3.49 and 3.03, respectively (all P > 0.05). The incidences of ADRs in the MR and EC groups were 6.61% (8/121) and 10.24% (13/127), respectively (P > 0.05). No serious ADRs were reported during the study.

Conclusion

Mesalazine modified-release tablets are non-inferior to enteric-coated tablets and are an effective and safe treatment option in Chinese patients with mildly to moderately active UC.

Trial registration

ClinicalTrials.gov identifier: NCT01257386.

Funding

Tillotts Pharma AG.

     

Mesalazine Modified-Release Tablet in the Treatment of Ulcerative Colitis in the Remission Phase: A Chinese,Multicenter, Single-Blind,Randomized Controlled Study

Introduction

This study aimed to compare the efficacy and safety of two mesalazine formulations in the treatment of Chinese patients with ulcerative colitis (UC) in the remission phase.

Methods

In this multicenter, single-blind, randomized controlled study conducted from November 2010 to August 2012, 251 patients with UC from 18 hospitals were enrolled. The patients were randomized to treatment with mesalazine modified-release tablets (MR group, n = 126) or other enteric-coated tablets (EC group, n = 125), at 800 mg three-times daily for 48 weeks. The primary efficacy parameter was the rate of non-emergence of bloody stool. If the lower limit of the 95% confidence interval (CI) of the primary efficacy measure was over ?10%, the modified-release tablets were considered non-inferior to the enteric-coated tablets. The secondary efficacy parameters included the period of non-emergence of bloody stool and the period of non-recurrence of UC. The incidences of adverse events and adverse drug reactions were compared between the two groups.

Results

At 48 weeks of maintenance treatment, the rates of non-emergence of bloody stool were 82.99% (95% CI 73.53–92.45%) and 73.30% (95% CI 64.04–82.56%) in the MR and EC groups, respectively, and the difference between the two groups was 9.69% (95% CI ?1.15–20.53%). There was no significant difference in the period of non-emergence of bloody stool and the period of non-recurrence of UC between the two groups (P > 0.05). The incidences of adverse events were 48.78% (60/123) and 48.00% (60/125) in the MR and EC groups, respectively (P = 0.902). The incidences of adverse drug reactions were 16.26% (20/123) and 13.60% (17/125) in the MR and EC groups, respectively (P = 0.556).

Conclusion

Mesalazine modified-release tablets were non-inferior to the enteric-coated tablets and may be considered an effective and safe treatment alternative for the maintenance of remission in Chinese patients with UC.

Trial registration

ClinicalTrials.gov identifier: NCT01257399.

Funding

Tillotts Pharma AG.

     

Distribution of lung ventilation in spontaneously breathing neonates lying in different body positions

Objective

The aim of our study was to determine the effect of the irregular spontaneous breathing pattern and posture on the spatial distribution of ventilation in neonates free from respiratory disease by the non-invasive imaging method of electrical impedance tomography (EIT). Scanning of spontaneously breathing neonates is the prerequisite for later routine application of EIT in babies with lung pathology undergoing ventilator therapy.

Design

Prospective study.

Setting

Neonatal intensive care unit at a university hospital.

Patients

Twelve pre-term and term neonates (mean age: 23 days; mean body weight: 2,465 g; mean gestational age: 34 weeks; mean birth weight: 2,040 g).

Interventions

Change in body position in the sequence: supine, right lateral, prone, supine.

Measurements and results

EIT measurements were performed using the Göttingen GoeMF I system. EIT scans of regional lung ventilation showing the distribution of respired air in the chest cross-section were generated during phases of rapid tidal breathing and deep breaths. During tidal breathing, 54.5±8.3%, 55.2±10.5%, 59.9±8.4% and 54.2±8.5% of inspired air (mean values ± SD) were directed into the right lung in the supine, right lateral, prone and repeated supine postures respectively. During deep inspirations, the right lung ventilation accounted for 52.6±7.9%, 68.5±8.5%, 55.4±8.2% and 50.5±6.6% of total ventilation respectively.

Conclusion

The study identified the significant effect of breathing pattern and posture on the spatial distribution of lung ventilation in spontaneously breathing neonates. The results demonstrate that changes in regional ventilation can easily be determined by EIT and bode well for the future use of this method in paediatric intensive care.

     

Pooled Aquablation Results for American Men with Lower Urinary Tract Symptoms due to Benign Prostatic Hyperplasia in Large Prostates (60–150 cc)

Introduction

To present short-term safety and efficacy data of men with lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH) treated with Aquablation.

Methods

Men with LUTs secondary to BPH (60–150 cc) underwent Aquablation treatment from February 2016 to December 2017 across 17 investigational sites in the USA from two contemporary investigational device exemption (IDE) studies called WATER (NCT02505919) and WATER II (NCT03123250).

Results

One hundred seven males with mean age of 67.3?±?6.5 years were treated with Aquablation; mean prostate volume was 99.4?±?24.1 cc. The pooled results show that large prostates have an average procedure time of less than 36 min and discharge on average 1.6?±?1 days. The IPSS decreased by 16.7?±?8.1 points at 3 months and Q_max increased by 11.2?±?12.4 ml/s. The Clavien-Dindo (CD) grade 2 or higher event rate at 3 months was 29%. A non-hierarchical breakdown for CD events yielded 18% grade 2 and 19% grade 3 or higher.

Conclusion

Men with LUTS secondary to BPH (60–150 cc) in a pooled analysis were treated safely and effectively with Aquablation up to 3 months postoperatively.

Trial Registration

ClinicalTrials.gov identifiers, NCT02505919 and NCT03123250.

Funding

PROCEPT BioRobotics.

     

Pancreatic transplants: secretin-stimulated MR pancreatography

Background

Our study was aimed to evaluate the functional status of pancreatic transplants using dynamic MR pancreatography after secretin stimulation.

Methods

Thirteen asymptomatic patients previously submitted to isolated pancreas (n = 6) or combined kidney–pancreas (n = 7) transplantation, with enteric-portal pancreatic drainage, underwent MR examination at 1.5 T using a phased-array coil. After the acquisition of axial and coronal T1- and T2-weighted sequences, dynamic MR pancreatography was performed using a coronal breath-hold, thick-slab (40–60 mm), single-shot T2-weighted fast spin-echo sequence. After the intravenous administration of secretin (Secrelux^®, Sanochemia; 1 cU/kg body/weight), a single-slice image acquisition was repeated every 30 s up to 15 min. We estimated the calibre changes of the pancreatic ductal system and the filling of the donor’s duodenum on the basis of pancreatic secretion after secretin stimulation, also evaluated by using a mean signal intensity/time histogram in a chosen region of interest including the transplanted pancreas and the connected small bowel.

Results

All patients well tolerated the examination, and no side effects were reported after secretin administration. In 12/13 cases, a significant increase (more than 1 mm) in the diameter of the mean pancreatic duct was observed after secretin stimulation; in all patients, a noticeable filling of the duodenal graft was demonstrated during dynamic MR pancreatography on both qualitative and quantitative analyses.

Conclusions

Dynamic MR imaging after secretin administration allows non-invasive evaluation of exocrine function of the pancreatic transplants and could be used to differentiate patients with graft rejection from those with normal graft function.

     

Optimization of non-contrast-enhanced MR angiography of the renal artery with three-dimensional balanced steady-state free-precession and time-spatial labeling inversion pulse (time-SLIP) at 3T MRI,in relation to age and blood velocity

Purpose

To determine the optimal inversion time (TI) value of three-dimensional (3D) balanced steady-state free-precession time-spatial labeling inversion pulse (time-SLIP) technique for visualization of the renal artery at 3T MRI, and to assess whether the optimal TI is affected by the subject’s age and blood velocity.

Materials and methods

Forty-two healthy volunteers (range 20–67 years) were enrolled in the study and subjected to non-contrast-enhanced renal MR angiography. Five different TI values (1200, 1400, 1600, 1800, and 2000 ms) were selected for evaluation. For quantitative evaluation, the relative signal intensity (SI) of the main renal artery was compared with that of the renal medulla (Vessel-to-Kidney ratio; VKR). Blood velocity of the abdominal aorta was measured using 2D phase contrast technique. For qualitative evaluation, two radiologists scored the depiction of the renal pelvis and the quality of visualization of the renal artery.

Results

VKR is the highest at TI = 1600 ms. A strong negative correlation between age and blood velocity was demonstrated. Regarding the qualitative evaluation, the overall image scores of renal arteries were the highest at a TI = 1800 ms for both readers. The optimal TI values in subjects below 50 years of age were 1600 and 1800 ms, whereas in subjects above 50 years of age, the optimal TI value was 1800 ms.

Conclusion

The optimal TI value for the visualization of renal arteries using time-SLIP technique at 3T MRI was 1800 ms. Subjects’ age affected optimal TI and this is likely due to differences in the blood velocity of the abdominal aorta.

     

Measurement of sound pressure and temperature in tissue-mimicking material using an optical fiber Bragg grating sensor

Purpose

The experimental investigation of an optical fiber Bragg grating (FBG) sensor for biomedical application is described. The FBG sensor can be used to measure sound pressure and temperature rise simultaneously in biological tissues exposed to ultrasound. The theoretical maximum values that can be measured with the FBG sensor are 73.0 MPa and 30 °C.

Methods

In this study, measurement of sound pressure up to 5 MPa was performed at an ultrasound frequency of 2 MHz. A maximum temperature change of 6 °C was measured in a tissue-mimicking material.

Results

Values yielded by the FBG sensor agreed with those measured using a thermocouple and a hydrophone.

Conclusion

Since this sensor is used to monitor the sound pressure and temperature simultaneously, it can also be used for industrial applications, such as ultrasonic cleaning of semiconductors under controlled temperatures.

     

Fully automatic detection of renal cysts in abdominal CT scans

Purpose

Simple renal cysts are a common benign finding in abdominal CT scans. However, since they may evolve in time, simple cysts need to be reported. With an ever-growing number of slices per CT scan, cysts are easily overlooked by the overloaded radiologist. In this paper, we address the detection of simple renal cysts as an incidental finding in a real clinical setting.

Methods

We propose a fully automatic framework for renal cyst detection, supported by a robust segmentation of the kidneys performed by a fully convolutional neural network. A combined 3D distance map of the kidneys and surrounding fluids provides initial candidates for cysts. Eventually, a second convolutional neural network classifies the candidates as cysts or non-cyst objects.

Results

Performance was evaluated on 52 abdominal CT scans selected at random in a real radiological workflow and containing over 70 cysts annotated by an experienced radiologist. Setting the minimal cyst diameter to 10 mm, the algorithm detected 59/70 cysts (true-positive rate = 84.3%) while producing an average of 1.6 false-positive per case.

Conclusions

The obtained results suggest the proposed framework is a promising approach for the automatic detection of renal cysts as incidental findings of abdominal CT scans.

     

MR-imaging features of hepatocellular carcinoma capsule appearance in cirrhotic liver: comparison of gadoxetic acid and gadobenate dimeglumine

Purpose

The purpose of the study is to compare the MR-imaging features of hepatocellular carcinoma (HCC) capsule appearance on gadoxetic acid and gadobenate dimeglumine-enhanced MR imaging, using imaging-based presumptive diagnosis of HCC as the reference standard.

Methods

Gadoxetic acid and gadobenate dimeglumine-enhanced MR imaging of 51 patients with 71 HCCs were retrospectively reviewed. Three readers graded in consensus, using a five-point scale, the presence (score 4–5) of capsule appearance on images obtained during T1-weighted GRE portal venous phase (PVP), 3-min phase, and hepatobiliary phase (HBP). The Fisher's exact test and the t student unpaired test were performed.

Results

A hyperintense capsule appearance was present either on PVP or 3-min phase in 11/46 and in 24/25 HCCs imaged with gadoxetic acid and gadobenate dimeglumine-enhanced MR imaging, respectively (24% vs. 96% p < 0.001). A hypointense capsule appearance was present on HBP in 8/46 and 0/22 HCCs evaluated with gadoxetic acid and gadobenate dimeglumine-enhanced MR imaging, respectively (17% vs. 0% p = 0.046). A capsule appearance was detected either on PVP, 3-min phase, or HBP in 17/46 (37%) HCCs after gadoxetic acid injection and in 24/25 (96%) HCCs after gadobenate dimeglumine injection (p < 0.001).

Conclusions

A capsule appearance was more frequently seen on gadobenate dimeglumine-enhanced MR imaging when compared to gadoxetic acid-enhanced MR imaging.

     

Thalamo-cortical network activity between migraine attacks: Insights from MRI-based microstructural and functional resting-state network correlation analysis

Background

Resting state magnetic resonance imaging allows studying functionally interconnected brain networks. Here we were aimed to verify functional connectivity between brain networks at rest and its relationship with thalamic microstructure in migraine without aura (MO) patients between attacks.

Methods

Eighteen patients with untreated MO underwent 3 T MRI scans and were compared to a group of 19 healthy volunteers (HV). We used MRI to collect resting state data among two selected resting state networks, identified using group independent component (IC) analysis. Fractional anisotropy (FA) and mean diffusivity (MD) values of bilateral thalami were retrieved from a previous diffusion tensor imaging study on the same subjects and correlated with resting state ICs Z-scores.

Results

In comparison to HV, in MO we found significant reduced functional connectivity between the default mode network and the visuo-spatial system. Both HV and migraine patients selected ICs Z-scores correlated negatively with FA values of the thalamus bilaterally.

Conclusions

The present results are the first evidence supporting the hypothesis that an abnormal resting within networks connectivity associated with significant differences in baseline thalamic microstructure could contribute to interictal migraine pathophysiology.