Prospective Comparison of Free-Breathing Accelerated Cine Deep Learning Reconstruction Versus Standard Breath-Hold Cardiac MRI Sequences in Patients With Ischemic Heart Disease.

BACKGROUND. Cine cardiac MRI sequences require repeated breath-holds, which can be difficult for patients with ischemic heart disease (IHD). OBJECTIVE. The purpose of the study was to compare a free-breathing accelerated cine sequence using deep learning (DL) reconstruction and a standard breath-hold cine sequence in terms of image quality and left ventricular (LV) measurements in patients with IHD undergoing cardiac MRI. METHODS. This prospective study included patients undergoing 1.5- or 3-T cardiac MRI for evaluation of IHD between March 15, 2023, and June 21, 2023. Examinations included an investigational free-breathing cine short-axis sequence with DL reconstruction (hereafter, cine-DL sequence). Two radiologists (reader 1 [R1] and reader 2 [R2]), in blinded fashion, independently assessed left ventricular ejection fraction (LVEF), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and subjective image quality for the cine-DL sequence and a standard breath-hold balanced SSFP sequence; R1 assessed artifacts. RESULTS. The analysis included 26 patients (mean age, 64.3 ± 11.7 [SD] years; 14 men, 12 women). Acquisition was shorter for the cine-DL sequence than the standard sequence (mean ± SD, 0.6 ± 0.1 vs 2.4 ± 0.6 minutes; p < .001). The cine-DL sequence, in comparison with the standard sequence, showed no significant difference for LVEF for R1 (mean ± SD, 51.7% ± 14.3% vs 51.3% ± 14.7%; p = .56) or R2 (53.4% ± 14.9% vs 52.8% ± 14.6%; p = .53); significantly greater LVEDV for R2 (mean ± SD, 171.9 ± 51.9 vs 160.6 ± 49.4 mL; p = .01) but not R1 (171.8 ± 53.7 vs 165.5 ± 52.4 mL; p = .16); and no significant difference in LVESV for R1 (mean ± SD, 88.1 ± 49.3 vs 86.0 ± 50.5 mL; p = .45) or R2 (85.2 ± 48.1 vs 81.3 ± 48.2 mL; p = .10). The mean bias between the cine-DL and standard sequences by LV measurement was as follows: LVEF, 0.4% for R1 and 0.7% for R2; LVEDV, 6.3 mL for R1 and 11.3 mL for R2; and LVESV, 2.1 mL for R1 and 3.9 mL for R2. Subjective image quality was better for cine-DL sequence than the standard sequence for R1 (mean ± SD, 2.3 ± 0.5 vs 1.9 ± 0.8; p = .02) and R2 (2.2 ± 0.4 vs 1.9 ± 0.7; p = .02). R1 reported no significant difference between the cine-DL and standard sequences for off-resonance artifacts (3.8% vs 23.1% examinations; p = .10) and parallel imaging artifacts (3.8% vs 19.2%; p = .19); blurring artifacts were more frequent for the cine-DL sequence than the standard sequence (42.3% vs 7.7% examinations; p = .008). CONCLUSION. A free-breathing cine-DL sequence, in comparison with a standard breath-hold cine sequence, showed very small bias for LVEF measurements and better subjective quality. The cine-DL sequence yielded greater LV volumes than the standard sequence. CLINICAL IMPACT. A free-breathing cine-DL sequence may yield reliable LVEF measurements in patients with IHD unable to repeatedly breath-hold. TRIAL REGISTRATION. ClinicalTrials.gov NCT05105984.

Acute pancreatitis and computed tomography: Interest of portal venous phase alone in the initial phase.

BACKGROUND: There are no guidelines in the literature for the use of a computed tomography (CT) protocol in the initial phase of acute pancreatitis (AP). PURPOSE: To evaluate the contribution of single portal venous phase CT compared to triple-phase CT protocol, performed in the initial phase of AP for severity assessment. MATERIAL AND METHODS: In this retrospective study, a total of 175 patients with acute pancreatitis who underwent initial triple-phase CT protocol (non-contrast, arterial phase, and portal venous phase) between D3 and D7 after the onset of symptoms were included. Analysis of AP severity and complications was independently assessed by two readers using three validated CT severity scores (CTSI, mCTSI, EPIC). All scores were applied to the triple-phase CT protocol and compared to the single portal venous phase. Inter-observer analyses were also performed. RESULTS: No significant difference whatever the severity score was observed after analysis of the single portal venous phase compared with the triple-phase CT protocol (interstitial edematous pancreatitis: CTSI: 2 vs. 2, mCTSI: 2 vs. 2, EPIC: 1 vs. 1; necrotizing pancreatitis: CTSI: 6 vs. 6, mCTSI: 8 vs. 8, EPIC: 5 vs. 5). Inter-observer agreement was excellent (ICC = 0.96-0.99), whatever the severity score. CONCLUSION: A triple-phase CT protocol performed at the initial phase of AP was no better than a single portal venous for assessing the severity of complications and could lead to a 63% reduction in irradiation.

A novel technique to perform cerebral angiography via the left radial approach: An 80 patients series.

PURPOSE: To demonstrate that left radial access for diagnostic cerebral angiography with Extra backup and 4F vertebral catheters is feasible and safe. MATERIALS AND METHODS: This study is a retrospective review of our prospective database on left radial access for cerebral angiography procedures, using an extra backup catheter associated with a 4Fr vertebral catheter, performed between March and September 2019. Patient demographics, procedural and radiographic metrics as well as clinical data were recorded. RESULTS: Seventy five patients with mean age of 51...years (range 21...73) underwent 80 cerebral angiographies. An average of four vessels were catheterized and mean fluoroscopy times per subject and vessel were was of 13.9 and 3.3...min, respectively. One patient required crossover to transfemoral access because of radial artery spasm. There were one asymptomatic distal radial artery occlusion and one patient presenting with asymptomatic skin blanching area on the forearm, just proximal to the tip of the sheath, that spontaneously resolved within an hour. CONCLUSION: Diagnostic cerebral angiography via left radial access is feasible and safe and allows to preserve the right radial access for future neurointerventions while providing more comfort to the right handed patient.

Diagnostic performance and image quality of deep learning image reconstruction (DLIR) on unenhanced low-dose abdominal CT for urolithiasis.

BACKGROUND: Patients with urolithiasis undergo radiation overexposure from computed tomography (CT) scans. Improvement of image reconstruction is necessary for radiation dose reduction. PURPOSE: To evaluate a deep learning-based reconstruction algorithm for CT (DLIR) in the detection of urolithiasis at low-dose non-enhanced abdominopelvic CT. MATERIAL AND METHODS: A total of 75 patients who underwent low-dose abdominopelvic CT for urolithiasis were retrospectively included. Each examination included three reconstructions: DLIR; filtered back projection (FBP); and hybrid iterative reconstruction (IR; ASiR-V 70%). Image quality was subjectively and objectively assessed using attenuation and noise measurements in order to calculate the signal-to-noise ratio (SNR), absolute contrast, and contrast-to-noise ratio (CNR). Attenuation of the largest stones were also compared. Detectability of urinary stones was assessed by two observers. RESULTS: Image noise was significantly reduced with DLIR: 7.2 versus 17 and 22 for ASiR-V 70% and FBP, respectively. Similarly, SNR and CNR were also higher compared to the standard reconstructions. When the structures had close attenuation values, contrast was lower with DLIR compared to ASiR-V. Attenuation of stones was also lowered in the DLIR series. Subjective image quality was significantly higher with DLIR. The detectability of all stones and stones >3 mm was excellent with DLIR for the two observers (intraclass correlation [ICC] = 0.93 vs. 0.96 and 0.95 vs. 0.99). For smaller stones (<3 mm), results were different (ICC = 0.77 vs. 0.86). CONCLUSION: For low-dose abdominopelvic CT, DLIR reconstruction exhibited image quality superior to ASiR-V and FBP as well as an excellent detection of urinary stones.

Distal radial access for cerebral aneurysm embolization.

OBJECTIVES: To demonstrate the feasibility and safety of distal radial access for embolization of ruptured and unruptured cerebral aneurysms. METHODS: This study is a retrospective review of our prospective cerebral aneurysm embolization database. Between January and September 2019, distal radial access was considered for consecutive subjects addressed for cerebral aneurysm embolization at our institution. All procedures were performed by the same experienced operator. Technical success was defined as distal radial access with insertion of the sheath and completion of the intervention without change of access site to conventional femoral access. Primary safety endpoint was the in hospital + 30 days incidence of radial artery occlusion. Secondary endpoints included intra-procedural complications and neurologic complications at discharge and at 30 days. RESULTS: Fifty-seven patients with cerebral aneurysms underwent 61 embolization procedures. Twenty eight embolizations were performed using coils, 8 used a stent-assisted coil technique, 22 used a balloon-assisted coil technique, and 3 used a flow diverter. One patient (1.6%) required crossover to femoral access. Three patients developed coil-induced thrombus that required intra-arterial Tirofiban injections. Two patients were asymptomatic and one patient presented confusion due to right frontal ischemia. One periprocedural aneurysm rupture occurred without clinical impact. Radial artery occlusion and hand ischemia were not observed. CONCLUSION: Findings of the present study showed the feasibility of distal transradial access for cerebral aneurysm embolization without increasing the risk of the procedure.

Safety and efficacy of percutaneous transhepatic-endoscopic rendezvous procedure in a single session.

PURPOSE: To demonstrate the feasibility and safety of PTE-RV performed in a single session. MATERIALS AND METHODS: This is a retrospective review of a prospective database on ERCP between January 2014 and December 2018. PTE-RV was performed in case of second ERCP failure. Technical success was defined as the establishment of an intestinal access to the biliary tract using a PTE-RV procedure allowing an immediate internal biliary drainage. Safety endpoints included intra-operative complications, morbidity and mortality occurring within 30 days after the procedure. RESULTS: Eighty-four patients (44 M/40F) with a median age of 69 years (range 40-91 years) underwent combined PTE-RV. The PTE-RVs were successfully performed in the same session in 80 subjects, resulting in an overall technical success rate of 95.2%. Adverse events were observed in 19% (16/84) of cases. The mortality rate within 30 days after the procedure was 9.5%. CONCLUSION: Percutaneous transhepatic-endoscopic rendezvous technique is feasible in a single session with acceptable level of risk. A randomized trial is required to compare EUBD and PTE-RV.

Diffusion and Flow MR Imaging to Investigate Hydrocephalus Patients Before and After Endoscopic Third Ventriculostomy.

INTRODUCTION: In patients with noncommunicating hydrocephalus, dilation of the ventricles stresses white matter fibers and alters the cerebral blood flow (CBF) and cerebrospinal fluid (CSF) dynamics. The purpose of this work was to investigate, non-invasively, how endoscopic third ventriculostomy (ETV) impacts white matter, CSF oscillations, and CBF. METHODS: Eleven patients presenting with chronic headaches and noncommunicating hydrocephalus due to aqueductal stenosis were treated by ETV. Phase Contrast-MRI (PCMRI) and Diffusion Tensor Imaging (DTI) were performed before and after surgery to evaluate CSF and CBF as well as white matter stresses in the Corpus Callosum (CC) and Corona Radiata (CR). ETV success was confirmed by quantification of the CSF oscillations through the aperture in the third ventricle. RESULTS: All patients improved after surgery. CSF stroke volume was five times greater than normal ventricular stroke volume. Decrease in cervical CSF oscillations and increase in CBF were observed after ETV. In CR, fiber anisotropy decreased, while water diffusion increased. In CC, anisotropy did not vary, while water diffusion also increased. CONCLUSION: Even if static ICP typically do not increase, CSF and blood flow are impacted. PCMRI and DTI can provide useful information to help neurosurgeons select patients with good chance to improve after ETV.

MRI Assessment of Right Ventricular Volumes and Function in Patients With Repaired Tetralogy of Fallot Using kat-ARC Accelerated Sequences.

OBJECTIVE. The objective of our study was to assess the accuracy and reproducibility of right ventricular volumes and function measurements in patients with repaired tetralogy of Fallot using two k-adaptive-t autocalibrating reconstruction for cartesian sampling (kat-ARC) accelerated sequences: a morphologic 3D cine sequence and a functional free-breathing 4D flow sequence. SUBJECTS AND METHODS. Seventeen patients who underwent cardiac MRI with gadolinium injection as part of follow-up of repaired tetralogy of Fallot from March 2017 to July 2018 were prospectively included in the initial study population; the final study cohort was composed of 15 of the 17 patients. Ventricle volume measurements were performed on a 3D cine kat-ARC sequence, a 4D flow kat-ARC sequence, and a 2D cine balanced steady-state free precession (bSSFP) sequence. The 2D cine bSSFP sequence was the reference standard in cardiac assessment. Intertechnique and interobserver analyses were performed. Bland-Altman analysis and correlation tests were used to compare quantitative measurements. RESULTS. Ventricular end-diastolic volume (EDV) and end-systolic volume (ESV) values were well correlated in the right ventricle (r = 0.94-0.98) for both 3D and 4D sequences. Ejection fraction (EF) also showed good correlation for both 3D and 4D sequences (r = 0.79 and r = 0.92). Bland-Altman analysis showed good agreement between right and left ventricular volumes, with narrower limits of agreement in the left ventricle, and an intraclass correlation coefficient (ICC) of greater than 0.80. For the 4D flow sequence, ventricular volumes were overestimated, which led to underestimation of the EF (bias for EDV = -10.2 mL, bias for ESV = -22.7 mL, bias for EF = 6.4%). Interobserver agreement was excellent for the ventricular volumes (ICC, 0.93-0.99) and fair to excellent for the EFs (ICC, 0.59-0.83). CONCLUSION. Compared with the reference standard 2D bSSFP sequence, the 3D cine kat-ARC accelerated sequence showed good accuracy and reproducibility for right ventricular measurements in patients with repaired tetralogy of Fallot. The short duration of the 4D flow kat-ARC sequence appears promising for performing volumetric measurements.

Quantification of blood flow in the superior ophthalmic vein using phase contrast magnetic resonance imaging.

Phase contrast magnetic resonance imaging (PC MRI), a validated, non-invasive technique for measuring intracranial blood and cerebrospinal flows, has been recently applied to studies of blood flow of the ophthalmic artery (OA). This study evaluated PC-MRI's ability to quantify blood flow in the superior ophthalmic vein (SOV). We analyzed with 3 T PC MRI the blood flow in the SOV in 11 healthy subjects and, for comparison purpose, in the OA. Segmentation software was used to analyze the PC images and quantify the variation in blood flow over the cardiac cycle in each of the vessels. The anatomy of the orbital veins was also assessed. We were able to measure the blood flow in 19 SOV; the mean ±â€¯standard deviation (SD) SOV flow was 9.13 ±â€¯7.10 mL/min with a mean ±â€¯SD variation of flow during cardiac cycle of 8.45 ±â€¯4.90 mL/min. The mean ±â€¯SD flow in the OA was 12.83 ±â€¯8.36 mL/min. The SOV was constantly present, with a mean cross-sectional area of 2.43 mm2. A medium and an inferior ophthalmic veins were found in 5 and 3 orbits, respectively. In conclusion, PC MRI is able to measure SOV as well as OA flows. To the best of our knowledge, the present study is the first to provide quantitative SOV blood flow values using PC MRI. Investigations of hydrocephalus, intracranial hypertension and even glaucoma might be facilitated by the application of this quantitative imaging modality.

Safety and Efficacy of Femoral Artery Closure with the FemoSeal Device After Cerebral Thrombectomy Using an 8 French Sheath.

PURPOSE: To evaluate the feasibility and safety of using the FemoSeal vascular closure device (VCD) to seal 8F access sites during mechanical thrombectomy for stroke. METHODS: A retrospective review of a prospective database was undertaken to evaluate the safety and efficacy of femoral arterial closure using FemoSeal device in all patients who underwent mechanical thrombectomy using an 8F sheath between January 2015 and July 2017. Efficacy endpoints were the successful deployment of the system and haemostasis success. Safety endpoints included the incidence of in hospital access site haematoma >5 cm, bleeding complications, pseudoaneurysms, arteriovenous fistula, infection, or other complications requiring surgery. RESULTS: 197 patients (96 men; mean age 68 years, range 25-99) were included. Successful haemostasis with FemoSeal was obtained in 98.9% of the patients. Only one haematoma >5 cm (0.5%) was observed, which reabsorbed spontaneously without issue. Nine haematomas <5 cm (4.5%) were also found. No major complications requiring surgical repair or transfusion were observed. There were no pseudoaneurysms, arteriovenous fistulae, or infections. CONCLUSION: The use of the FemoSeal device to close an 8F access sheath puncture site is feasible and safe, with a low complication rate.

Cerebrospinal Fluid and Cerebral Blood Flows in Idiopathic Intracranial Hypertension.

OBJECTIVES: Cerebrospinal fluid (CSF) and blood flows have a strong relationship during a cardiac cycle. Idiopathic intracranial hypertension (IIH) is a pathology that seems to present hemodynamic and hydrodynamic disturbance. The aim of this study was to establish CSF and blood interaction in IIH. MATERIAL AND METHODS: We retrospectively studied cerebral hydrodynamic and hemodynamic flows by phase-contrast MRI (PCMRI) in 13 IIH subjects (according Dandy's criteria) and 16 controls. We analyzed arterial peak flow, pulsatility index, and resistive index in arterial and venous compartments (PFart, PIart, RIart, PFvein, PIvein, RIvein) and measured arteriovenous and CSF peak flow and stroke volume (PFav, SVVASC, PFCSF, SVCSF). RESULTS: We found no significant difference between IIH and control groups in arterial and venous parameters. Arteriovenous flow analysis showed higher PFav and SVVASC in the IIH group than in the control group (respectively 369 ± 27 mL/min and 286 ± 47 mL/min, p = 0.02; and 1085 ± 265 µL/cardiac cycle and 801 ± 226 µL/cardiac cycle, p = 0.007). PFCSF and SVCSF were higher in the IIH group than in the control group (respectively 206 ± 50 mL/min and 126.6 ± 24.8 mL/min, p = 0.04; and 570 ± 190 µL/cardiac cycle and 430 ± 100 µL/cardiac cycle, p = 0.0007). CONCLUSION: Although no significant change was found in arterial and venous flows, we showed that a small phase shift of venous outflow might cause an increase in the arteriovenous pulsatility and an increasing brain expansion during the cardiac cycle. This arteriovenous flow increase would result in an increase of CSF flushing through the foramen magnum and an increased ICP.

Heart rate and respiration influence on macroscopic blood and CSF flows.

Background Changes in blood volume in the intracranial arteries and the resulting oscillations of brain parenchyma have been presumed as main initiating factors of cerebrospinal fluid (CSF) pulsations. However, respiration has been recently supposed to influence CSF dynamics via thoracic pressure changes. Purpose To measure blood and CSF cervical flow and quantify the contribution of cardiac and respiratory cycles on the subsequent signal evolution. Material and Methods Sixteen volunteers were enrolled. All participant underwent two-dimensional fast field echo echo planar imaging (FFE-EPI). Regions of interest were placed on internal carotids, jugular veins, and rachidian canal to extract temporal profiles. Spectral analysis was performed to extract respiratory and cardiac frequencies. The contribution of respiration and cardiac activity was assessed to signal evolution by applying a multiple linear model. Results Mean respiratory frequency was 14.6 ± 3.9 cycles per min and mean heart rate was 66.8 ± 9 cycles per min. Cardiac contribution was higher than breathing for internal carotids, explaining 74.68% and 10.27% of the signal variance, respectively. For the jugular veins, respiratory component was higher than the cardiac one contributing 44.28% and 6.53% of the signal variance, respectively. For CSF, breathing and cardiac component contributed less than half of signal variance (12.61% and 23.23%, respectively). Conclusion Respiration and cardiac activity both influence fluid flow at the cervical level. Arterial inflow is driven by the cardiac pool whereas venous blood aspiration seems more due to thoracic pressure changes. CSF dynamics acts as a buffer between these two blood compartments.

Effect of surgery on periventricular white matter in normal pressure hydrocephalus patients: comparison of two methods of DTI analysis.

BACKGROUND: Diffusion tensor imaging (DTI) is a useful tool for assessing changes that occur in microstructures. We have developed a novel method for region of interest (ROI) delineation in the assessment of DTI parameters in patients with normal pressure hydrocephalus (NPH). PURPOSE: To compare the standard method and our novel method in an evaluation of the impact of surgery on periventricular white matter in patients with NPH. MATERIAL AND METHODS: Ten patients with NPH underwent 3T magnetic resonance imaging (MRI; including 12-direction DTI sequences) before and after surgery. We recorded diffusion parameters (λi, the fractional anisotropy [FA], the apparent diffusion coefficient, and Dr) in the internal capsule (IC) and the body of the corpus callosum (BCC). Using the standard delineation technique, regions of interest (ROIs) were positioned according to anatomical and functional considerations and then filled with several sub-ROIs. The ROIs delineated with our novel technique (extracted as the six sub-ROIs with the lowest standard deviation for the FA) were arranged in two rows (medial and lateral), from the ventricle to the brain surface. RESULTS: The within-ROI homogeneity was higher with the novel method than with the conventional method (P<10(-4)). When the conventional delineation method was applied to the IC data, only λ2 was found to be significantly greater after surgery; in contrast, application of our novel method evidenced a significant decrease in FA and λ1 and a significant increase in λ2 (P<0.05). Both before and after surgery, the FA in the medial row of ROIs was greater than the FA in the lateral row (P<0.01). In the BCC, only λ2 and Dr varied significantly (when evaluated with the novel method). CONCLUSION: Our results show that use of a novel method of DTI data analysis may be more sensitive to local changes induced by surgical procedures. Furthermore, this novel method was able to detect the transmantle pressure gradient related to the regional stress distribution.

Relationship between cerebrospinal fluid flow, ventricles morphology, and DTI properties in internal capsules: differences between Alzheimer's disease and normal-pressure hydrocephalus.

BACKGROUND: Normal-pressure hydrocephalus (NPH) and Alzheimer's disease (AD) have some similar clinical features and both involve white matter and cerebrospinal fluid (CSF) disorders. PURPOSE: To compare putative relationships between ventricular morphology, CSF flow, and white matter diffusion in AD and NPH. MATERIAL AND METHODS: Thirty patients (18 with AD and 12 with suspected NPH) were included in the study. All patients underwent a 3-Tesla MRI scan, which included phase-contrast MRI of the aqueduct (to assess the aqueductal CSF stroke volume) and a DTI session (to calculate the fractional anisotropy [FA] and apparent diffusion coefficient [ADC]) in the internal capsules). RESULTS: FA was correlated with ventricular volume in the suspected NPH population (P < 0.001; rs = 0.88), whereas the ADC was highly correlated with the aqueductal CSF stroke volume in AD (P < 0.001; rs = 0.79). CONCLUSION: Although AD and NPH both involve CSF disorders, the two diseases do not have the same impact on the internal capsules. The magnitude of the ADC is related to the aqueductal CSF stroke volume in AD, whereas FA is related to ventricular volume in NPH.

Robotically assisted deployment of flow diverter stents for the treatment of cerebral and cervical aneurysms.

BACKGROUND: Despite the growing sophistication of robot-assisted surgery, it is necessary to demonstrate that robots can reliably perform complex procedures on site and then remotely. Although a flow diverter stent is one of the most effective and widely used devices, its placement is sometimes challenging. OBJECTIVE: To evaluate the feasibility and safety of the CorPath GRX robotic platform for the embolization of cerebral and cervical aneurysms using flow diverter stents. METHODS: We performed a single-center technical study of the first 10 flow diverter stent deployments with the CorPath GRX Robotic System (Corindus Inc, Waltham, Massachusetts, USA) for the treatment of cerebral aneurysms between April and October 2022. RESULTS: Ten patients underwent robot-assisted embolization with flow diverter stents: there were nine intracranial aneurysms (paraclinoid n=6; posterior communicating artery aneurysm n=1; anterior communicating artery n=2) and one cervical aneurysm. Four procedures were performed with coils plus a flow diverter stent, one was performed with woven endobridge plus a flow diverter stent and four were performed with flow diverter stents alone. Of these procedures, two were performed with telescoping flow diverters.All flow diverter stents were deployed with robotic assistance, with only one partial conversion to a manual technique (caused by guidewire torquability limitations). No perioperative complications were observed. CONCLUSION: Robot-assisted flow diverter stent deployment using the CorPath GRX platform is feasible and appears to be safe. Larger, in-depth studies of the technique's safety and benefits are now warranted.

Detection of urinary tract stones on submillisievert abdominopelvic CT imaging with deep-learning image reconstruction algorithm (DLIR).

PURPOSE: Urolithiasis is a chronic condition that leads to repeated CT scans throughout the patient's life. The goal was to assess the diagnostic performance and image quality of submillisievert abdominopelvic computed tomography (CT) using deep learning-based image reconstruction (DLIR) in urolithiasis. METHODS: 57 patients with suspected urolithiasis underwent both non-contrast low-dose (LD) and ULD abdominopelvic CT. Raw image data of ULD CT were reconstructed using hybrid iterative reconstruction (ASIR-V 70%) and high-strength-level DLIR (DLIR-H). The performance of ULD CT for the detection of urinary stones was assessed by two readers and compared with LD CT with ASIR-V 70% as a reference standard. Image quality was assessed subjectively and objectively. RESULTS: 266 stones were detected in 38 patients. Mean effective dose was 0.59 mSv for ULD CT and 1.96 mSv for LD CT. For diagnostic performance, sensitivity and specificity were 89% and 94%, respectively, for ULDCT with DLIR-H. There was an almost perfect intra-observer concordance on ULD CT with DLIR-H versus LDCT with ASIR-V 70% (ICC = 0.90 and 0.90 for the two readers). Image noise was significantly lower and signal-to-noise ratio significantly higher with DLIR-H compared to ASIR-V 70%. Subjective image quality was also significantly better with ULDCT with DLIR-H. CONCLUSION: ULD CT with Deep Learning Image Reconstruction maintains a good diagnostic performance in urolithiasis, with better image quality than hybrid iterative reconstruction and a significant radiation dose reduction.

Measurement of choroid plexus perfusion using dynamic susceptibility MR imaging: capillary permeability and age-related changes.

INTRODUCTION: The cerebrospinal fluid (CSF) plays a major role in the physiology of the central nervous system. The continuous turnover of CSF is mainly attributed to the highly vascularized choroid plexus (CP) located in the cerebral ventricles which represent a complex interface between blood and CSF. We propose a method for evaluating CP functionality in vivo using perfusion MR imaging and establish the age-related changes of associated parameters. METHODS: Fifteen patients with small intracranial tumors were retrospectively studied. MR Imaging was performed on a 3T MR Scanner. Gradient-echo echo planar images were acquired after bolus injection of gadolinium-based contrast agent (CA). The software developed used the combined T1- and T2-effects. The decomposition of the relaxivity signals enables the calculation of the CP capillary permeability (K2). The relative cerebral blood volume (rCBV), mean transit time (MTT), and signal slope decrease (SSD) were also calculated. RESULTS: The mean permeability K2 of the extracted CP was 0.033+/-0.18 s(-1). K2 and SSD significantly decreased with subject's age whereas MTT significantly increased with subject's age. No significant correlation was found for age-related changes in rCBV and rCBF. CONCLUSION: The decrease in CP permeability is in line with the age-related changes in CSF secretion observed in animals. The MTT increase indicates significant structural changes corroborated by microscopy studies in animals or humans. Overall, DSC MR-perfusion enables an in vivo evaluation of the hemodynamic state of CP. Clinical applications such as neurodegenerative diseases could be considered thanks to specific functional studies of CP.

Phantom study of an in-house amplitude-gating respiratory method with silicon photomultiplier technology positron emission tomography/computed tomography.

PURPOSE: The objective of this phantom study was to determine whether breathing-synchronized, silicon photomultiplier (SiPM)-based PET/CT has a suitable acquisition time for routine clinical use. METHODS: Acquisitions were performed in list mode on a 4-ring SiPM-based PET/CT system. The experimental setup consisted of an external respiratory tracking device placed on a commercial dynamic thorax phantom containing a sphere filled with [F-18]-fluorodeoxyglucose. Three-dimensional sinusoidal motion was imposed on the sphere. Data were processed using frequency binning and amplitude binning (the "DMI" and "OFFLINE" methods, respectively). PET sinograms were reconstructed with a Bayesian penalized likelihood algorithm. RESULTS: Respiratory gating from a 150­sec acquisition was successful. The DMI and OFFLINE methods gave similar activity profiles but both were slightly shifted in space; the latter profile was closest to the reference acquisition. CONCLUSION: With SiPM PET/CT systems, the amplitude-based processing of breathing-synchronized data is likely to be feasible in routine clinical practice.

Pulmonary emphysema quantification at low dose chest CT using Deep Learning image reconstruction.

PURPOSE: Quantitative analysis of emphysema volume is affected by the radiation dose and the CT reconstruction technique. We aim to evaluate the influence of a commercially available deep learning image reconstruction algorithm (DLIR) on the quantification of pulmonary emphysema in low-dose chest CT. METHODS: We performed a retrospective study of low dose chest CT scans in 54 patients with chronic obstructive pulmonary disease (COPD). Raw data were reconstructed using FBP, iterative reconstruction (ASIR-V 70%) and deep learning based algorithms at high, medium and low-strength (DLIR -H, -M, -L). Filtered FBP images served as reference. Pulmonary emphysema volume (proportion of voxels below -950 UH) was measured on each reconstruction dataset and visually assessed by a chest radiologist. Quantitative image quality was assessed by placing 3 regions of interest in the trachea, in air and in a paraspinal muscle. Signal to noise ratio was also measured. RESULTS: The mean CDTIvol was 2.38 ± 0.68 mGy. Significant differences in emphysema volumes between the filtered FBP reference and ASIR-V, DLIR-H, DLIR-M or DLIR-L were observed, (p < 10-3) for all. A strong correlation between filtered FBP volumes and DLIR-H was reported (r = 0.999, p < 10-4), a 10% overestimation with DLIR-H being observed. Noise was significantly reduced in DLIR-H volumes compared to the other reconstruction methods. Signal to noise ratio was improved when using DLIR-H (p < 10-6). CONCLUSION: There are significant differences regarding emphysema volumes between FBP, iterative reconstruction or deep learning-based DLIR algorithm. DLIR-H shows the closest correlation to filtered FBP while increasing SNR.