Water and lipid content of breast tissue measured by six-wavelength time-domain diffuse optical spectroscopy.

Significance: The water and lipid content of normal breast tissue showed mammary gland characteristics with less influence from the chest wall using six-wavelength time-domain diffuse optical spectroscopy (TD-DOS) in a reflectance geometry. Aim: To determine the depth sensitivity of a six-wavelength TD-DOS system and evaluate whether the optical parameters in normal breast tissue can distinguish dense breasts from non-dense breasts. Approach: Measurements were performed in normal breast tissue of 37 breast cancer patients. We employed a six-wavelength TD-DOS system to measure the water and lipid content in addition to the hemoglobin concentration. The breast density in mammography and optical parameters were then compared. Results: The depth sensitivity of the system for water and lipid content was estimated to be ∼15 mm. Our findings suggest that the influence of the chest wall on the water content is weaker than that on the total hemoglobin concentration. In data with evaluation conditions, the water content was significantly higher (p < 0.001) and the lipid content was significantly lower (p < 0.001) in dense breast tissue. The water and lipid content exhibited a high sensitivity and specificity to distinguish dense from non-dense breasts in receiver-operating-characteristic curve analysis. Conclusions: With less influence from the chest wall, the water and lipid content of normal breast tissue measured by a reflectance six-wavelength TD-DOS system, together with ultrasonography, can be applied to distinguish dense from non-dense breasts.

Temporal subtraction of low-dose and relatively thick-slice CT images with large deformation diffeomorphic metric mapping and adaptive voxel matching for detection of bone metastases: A STARD-compliant article.

To evaluate the improvement of radiologist performance in detecting bone metastases at follow up low-dose computed tomography (CT) by using a temporal subtraction (TS) technique based on an advanced nonrigid image registration algorithm.Twelve patients with bone metastases (males, 5; females, 7; mean age, 64.8 ±â€Š7.6 years; range 51-81 years) and 12 control patients without bone metastases (males, 5; females, 7; mean age, 64.8 ±â€Š7.6 years; 51-81 years) were included, who underwent initial and follow-up CT examinations between December 2005 and July 2016. Initial CT images were registered to follow-up CT images by the algorithm, and TS images were created. Three radiologists independently assessed the bone metastases with and without the TS images. The reader averaged jackknife alternative free-response receiver operating characteristics figure of merit was used to compare the diagnostic accuracy.The reader-averaged values of the jackknife alternative free-response receiver operating characteristics figures of merit (θ) significantly improved from 0.687 for the readout without TS and 0.803 for the readout with TS (P value = .031. F statistic = 5.24). The changes in the absolute value of CT attenuations in true-positive lesions were significantly larger than those in false-negative lesions (P < .001). Using TS, segment-based sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the readout with TS were 66.7%, 98.9%, 94.4%, 90.9%, and 94.8%, respectively.The TS images can significantly improve the radiologist's performance in the detection of bone metastases on low-dose and relatively thick-slice CT.

Optimal Plane Selection for Measuring Post-prandial Blood Flow Increase within the Superior Mesenteric Artery: Analysis Using 4D Flow and Computational Fluid Dynamics.

PURPOSE: 2D cine phase contrast (PC)-MRI is a standard velocimetry for the superior mesenteric artery (SMA); however, the optimal localization of the measurement plane has never been fully discussed previously. The purpose of this Institutional Review Board approved prospective and single arm study is to test whether flow velocimetry of the SMA with combined use of 2D cine PC-MRI and meal challenge is dependent on the localizations of the measurement planes and to seek optimal section for velocimetry. METHODS: Seven healthy volunteers underwent cardiac phase resolved ECG gated 2D cine PC-MRI pre- and 30 min post-meal challenge at three measurement planes: proximal, curved mid section and distal straight section of the SMA at 3T. 4D Flow using 3D cine PC-MRI with vastly undersampled isotropic projection imaging (PC VIPR) was also performed right after 2D cine PC-MRI to delineate the flow dynamics within the SMA using streamline analysis. Two radiologists measured flow velocities, and rated the appearances of the abnormal flow in the SMA on streamlines derived from the 4D Flow and the computational fluid dynamics (CFD). RESULTS: 2D cine PC-MRI measured increased temporally averaged flow velocity (mm/s) after the meal challenge only in the proximal (129.3 vs. 97.8, P = 0.0313) and distal section (166.9 vs. 96.2, P = 0.0313), not in the curved mid section (113.1 vs. 85.5, P = 0.0625). The average velocities were highest and their standard errors (8.5-26.5) were smallest at the distal straight section both before and after the meal challenge as compared with other sections. The streamline analysis depicted more frequent appearances of vertical or helical flow in the curved mid section both on 4D Flow and CFD (κ: 0.27-0.68). CONCLUSION: SMA velocimetry with 2D cine PC-MRI was dependent on the localization of the measurement planes. Distal straight section, not in the curved mid section is recommended for MR velocimetry.

Assessing the Risk of Intracranial Aneurysm Rupture Using Morphological and Hemodynamic Biomarkers Evaluated from Magnetic Resonance Fluid Dynamics and Computational Fluid Dynamics.

PURPOSE: Evaluate in vivo hemodynamic and morphological biomarkers of intracranial aneurysms, using magnetic resonance fluid dynamics (MRFD) and MR-based patient specific computational fluid dynamics (CFD) in order to assess the risk of rupture. METHODS: Forty-eight intracranial aneurysms (10 ruptured, 38 unruptured) were scrutinized for six morphological and 10 hemodynamic biomarkers. Morphological biomarkers were calculated based on 3D time-of-flight magnetic resonance angiography (3D TOF MRA) in MRFD analysis. Hemodynamic biomarkers were assessed using both MRFD and CFD analyses. MRFD was performed using 3D TOF MRA and 3D cine phase-contrast magnetic resonance imaging (3D cine PC MRI). CFD was performed utilizing patient specific inflow-outflow boundary conditions derived from 3D cine PC MRI. Univariate analysis was carried out to identify statistically significant biomarkers for aneurysm rupture and receiver operating characteristic (ROC) analysis was performed for the significant biomarkers. Binary logistic regression was performed to identify independent predictive biomarkers. RESULTS: Morphological biomarker analysis revealed that aneurysm size [P = 0.021], volume [P = 0.035] and size ratio [P = 0.039] were statistically significantly different between the two groups. In hemodynamic biomarker analysis, MRFD results indicated that ruptured aneurysms had higher oscillatory shear index (OSI) [OSI.max, P = 0.037] and higher relative residence time (RRT) [RRT.ave, P = 0.035] compared with unruptured aneurysms. Correspondingly CFD analysis demonstrated significant differences for both average and maximum OSI [OSI.ave, P = 0.008; OSI.max, P = 0.01] and maximum RRT [RRT.max, P = 0.045]. ROC analysis revealed AUC values greater than 0.7 for all significant biomarkers. Aneurysm volume [AUC, 0.718; 95% CI, 0.491-0.946] and average OSI obtained from CFD [AUC, 0.774; 95% CI, 0.586-0.961] were retained in the respective logistic regression models. CONCLUSION: Both morphological and hemodynamic biomarkers have significant influence on intracranial aneurysm rupture. Aneurysm size, volume, size ratio, OSI and RRT could be potential biomarkers to assess aneurysm rupture risk.

Effect of Source-Detector Distance on the Measurement of Hemoglobin Using Near-Infrared Spectroscopy in Breast Cancer.

We measured total hemoglobin concentrations in breast tumors by near-infrared time-resolved spectroscopy. Muscles interfere with measurement when the probe is close to the chest wall. Since the target area of measurement depends on the distance between the light source and probe detector, we inferred that this issue could be solved by reducing the source-detector distance. The purpose of this study was to examine the effects of the source-detector distance on the measurement of total hemoglobin concentration in the breast. We examined 26 patients with breast tumors. Total hemoglobin concentration was measured in tumors and the contralateral normal breasts at source-detector distances of 20 and 30 mm. The difference in total hemoglobin concentration between each tumor and the contralateral breast was calculated. The normal breast total hemoglobin concentration was significantly smaller for the source-detector distance of 20 mm than for the source-detector distance of 30 mm. Differences in source-detector distance did not significantly affect tumor total hemoglobin. The difference in total hemoglobin concentration between the tumor and the contralateral breast obtained at the source-detector distance of 20 mm was significantly higher than that obtained at the source-detector distance of 30 mm. From these results, we considered that measurement with a source-detector distance of 20 mm is less affected by the chest wall than with a source-detector distance of 30 mm and that the difference in total hemoglobin concentration between the tumor and the contralateral breast at a source-detector distance of 20 mm can better reflect the net total hemoglobin concentrations of the breast tumors. In conclusion, using a probe with a source-detector distance of 20 mm can more accurately evaluate the total hemoglobin concentration in breast tumors.

Stable tissue-simulating phantoms with various water and lipid contents for diffuse optical spectroscopy.

We introduced a method for producing solid phantoms with various water-to-lipid ratios that can simulate the absorption, and to some extent the scattering characteristics of human breast tissue. We also achieved phantom stability for a minimum of one month by solidifying the emulsion phantoms. The characteristics of the phantoms were evaluated using the six-wavelength time-domain diffuse optical spectroscopy (TD-DOS) system we developed to measure water and lipid contents and hemoglobin concentration. The TD-DOS measurements were validated with a magnetic resonance imaging system.

Mesenchymal chondrosarcoma of the orbit: imaging features of CT and MRI.

OBJECTIVE:: Mesenchymal chondrosarcoma (MCS) of the orbit is a rare and aggressive form of chondrosarcoma. The purpose of this study was to retrospectively identify the imaging features of mesenchymal chondrosarcoma of the orbit. METHODS:: This study included five patients with histologically confirmed MCS of the orbit who had undergone either CT, MRI, or both. Images were evaluated for the following: location, size, margin, CT density and presence or absence of calcification and/or ossification, MRI findings including dynamic contrast-enhancement and time-intensity curves. RESULTS:: CT was performed in four of the five patients, and all four (100%) demonstrated calcification and ossification of the mass. MRI was performed in all five patients. In two patients (40%), the mass demonstrated areas of hyperintensity on T1 weighted images. CONCLUSION:: The presence of a well-defined, orbital mass with calcification and ossification on CT and, marked heterogenous enhancement and a rapid-washout pattern on dynamic MRI indicate a high probability of MCS of the orbit. In addition, MCS of the orbit can demonstrate areas of hyperintensity on T1 weighted images, representing bone marrow fat tissue of ossification. ADVANCES IN KNOWLEDGE:: MCS of the orbit is a highly malignant tumor, and early diagnosis by imaging is important. Radiologists should be aware of the imaging features of MCS of the orbit.

Factors affecting measurement of optic parameters by time-resolved near-infrared spectroscopy in breast cancer.

The purpose of this study was to evaluate the effects of the thickness and depth of tumors on hemoglobin measurements in breast cancer by optical spectroscopy and to demonstrate tissue oxygen saturation (SO2) and reduced scattering coefficient (µs') in breast tissue and breast cancer in relation to the skin-to-chest wall distance. We examined 53 tumors from 44 patients. Total hemoglobin concentration (tHb), SO2, and µs' were measured by time-resolved spectroscopy (TRS). The skin-to-chest wall distance and the size and depth of tumors were measured by ultrasonography. There was a positive correlation between tHb and tumor thickness, and a negative correlation between tHb and tumor depth. SO2 in breast tissue decreased when the skin-to-chest wall distance decreased, and SO2 in tumors tended to be lower than in breast tissue. In breast tissue, there was a negative correlation between µs' and the skin-to-chest wall distance, and µs' in tumors was higher than in breast tissue. Measurement of tHb in breast cancer by TRS was influenced by tumor thickness and depth. Although SO2 seemed lower and µs' was higher in breast cancer than in breast tissue, the skin-to-chest wall distance may have affected the measurements.

18F-FDG PET/CT Findings of Mesenchymal Chondrosarcoma of the Orbit.

Mesenchymal chondrosarcoma of the orbit is an extremely rare and aggressive tumor. We report image findings of F-fluorodeoxyglucose (FDG) positron emission/computed tomography (PET/CT) in 2 cases, one primary case and one recurrent case. The F-FDG PET/CT images revealed high uptake with an SUVmax of 6.7 and 11.7, respectively. In both cases, the HEY1-CoA2 gene fusion was positive. The high uptake of F-FDG in mesenchymal chondrosarcoma of the orbit well suggests the malignancy of this tumor.

Four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction (4D PC-VIPR) MR evaluation of the renal arteries in transplant recipients: Preliminary results.

PURPOSE: To assess the performance of four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction (4D PC-VIPR) at 3.0T in depicting intrarenal arteries compared with computed tomography angiography (CTA), and its correlation with arterial flowmetry in comparison with Doppler ultrasonography (DUS). MATERIALS AND METHODS: In our prospective single-arm study, subjects were 25 patients who underwent renal transplant-related surgery at our hospital between July 2011 and June 2015. In the morphological study, depictions of renal artery branches delineated by magnetic resonance angiography (MRA)/4D PC-VIPR without gadolinium contrast agent were compared in seven living transplant recipients with the same kidney delineated by CTA in seven living transplant donors. In the flowmetric study, flow velocities in the renal (main stem), segmental, and interlobar arteries during systole and diastole were measured in 12 recipients using noncontrast MRA/4D PC-VIPR, and were compared with those obtained from DUS. RESULTS: Concerning MRA, average confidence levels of delineation rated by six observers for secondary to third level renal artery branches were 82.9-100% and for the fourth to fifth branches were 60.8-89.7% (average kappa value of 0.588 [95% confidence interval: 0.522-0.653]). Total flow velocities measured using 4D PC-VIPR and DUS demonstrated significant correlations during both systole and diastole with acceptable bias (r = 0.902; P < 0.001 in systole and r = 0.734; P < 0.001 in diastole). CONCLUSION: 4D PC-VIPR was useful in generating both morphological and hemodynamic information for evaluation of transplant intrarenal arteries without the need for contrast media. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:595-603.

Non-invasive evaluation of pulmonary arterial blood flow and wall shear stress in pulmonary arterial hypertension with 3D phase contrast magnetic resonance imaging.

BACKGROUND: Recently, time-resolved 3D phase contrast magnetic resonance imaging (4D-flow) allows flow dynamics in patients with pulmonary arterial hypertension to be measured. Abnormal flow dynamics, such as vortex blood flow pattern in the pulmonary artery (PA), may reflect progression of pulmonary arterial hypertension (PAH). Some reports suggested that abnormal blood flow parameters including wall shear stress (WSS) could be markers of PAH. However, it was not fully assessed clinical usefulness of these variables. We aimed to assess whether these flow dynamic parameters, such as vortex formation time (VFT) and WSS, were associated with right ventricular (RV) function. RESULTS: Fifteen subjects, nine with PAH and six healthy volunteers, underwent 4D-flow. Differences of Blood flow patterns, blood flow velocities and WSS between PAH patients and healthy volunteers were evaluated. We also assessed the association between VFT, WSS and RV function in PAH patients. Both vortex blood flow patterns and early systolic retrograde flow in the main PA were observed in all patients with PAH. The PA flow velocities and WSS in patients with PAH were lower than those in healthy volunteers, but that blood flow volumes in the MPA, RPA and LPA and SV in the MPA were broadly comparable between the groups. The mean VFT was 35.0 ± 16.6 % of the cardiac cycle. The VFT significantly correlated with RV ejection fraction, RV end systolic volume, and RV end systolic volume index (RVEF = 75.1 + (-85.7)·VFT, p = 0.003, RVESV = 12.4 + 181.8·VFT, p = 0.037 and RVESVI = 10.6 + 114.8·VFT, p = 0.038, respectively) in PAH patients, whereas WSS did not correlate with RV function. CONCLUSIONS: We confirmed that abnormal blood flow dynamics, including the vortex formation and the early onset of retrograde flow, low WSS in the PA were characteristics of PAH. The VFT may be associated with right ventricular dysfunction, whereas WSS was not. Our results suggest that 4D-flow is an effective means of detecting right heart failure as well as diagnosing PAH. CLINICAL TRIAL REGISTRATION URL: https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi. Unique identifier: UMIN000011128.

Hemodynamic Analysis of Endoleaks After Endovascular Abdominal Aortic Aneurysm Repair by Using 4-Dimensional Flow-Sensitive Magnetic Resonance Imaging.

BACKGROUND: An endoleak is a common complication of endovascular abdominal aortic aneurysm repair (EVAR), and it can be associated with aneurysmal growth. This pilot study used 4-dimensional flow-sensitive magnetic resonance imaging (4D-flow) to assess the hemodynamics of different types of endoleaks (I-IV). METHODS AND RESULTS: Magnetic resonance angiography, 4D-flow, and computed tomography angiography (CTA) were performed in 31 patients after nitinol-based stent-graft deployment. With 4D-flow, the 3D streamlines of endoleaks appear as integrated traces along the instantaneous velocity vector field that are color-coded according to the local velocity magnitude of the leak. The 4D-flow analysis identified endoleaks in 18 patients (58.1%), whereas CTA identified endoleaks in 13 patients (41.9%). The 4D-flow analysis created a characteristic image of each type of endoleak. Among patients with endoleaks, 4D-flow identified concomitant multiple endoleaks in 7 (39%) patients, and it further differentiated type II endoleaks from type IIa endoleaks (to-and-fro biphasic flow pattern from a branch vessel) and from type IIb endoleaks (monophasic flow pattern with a connection between the inflow and outflow branches). CONCLUSIONS: The 4D-flow analysis was more sensitive than CTA for detecting an endoleak, and it could subclassify type II endoleaks. In addition, 4D-flow differentiated between concomitant endoleak types in a single patient. (Circ J 2016; 80: 1715-1725).

Intra-left ventricular flow dynamics in patients with preserved and impaired left ventricular function: Analysis with 3D cine phase contrast MRI (4D-Flow).

PURPOSE: To examine how left ventricular (LV) volume and function affect flow dynamics by analyzing 3D intra-LV vortex features using 4D-Flow. MATERIALS AND METHODS: Twenty-one patients with preserved (LVEF > 60%) and 14 with impaired LV function (LVEF < 40%) underwent 4D-Flow (at 3T). RESULTS: In patients with preserved LV function, the intra-LV vortices developed in both the early and late diastolic phases. The shift of inflow vectors at the basal LV toward the posterior-lateral side of the LV and the mid-ventricular turn of inflow vectors toward the LV outflow could explain clearer vortex formation in the late diastolic phase. In patients with impaired LV function, the intra-LV vortices during the diastolic phase located at the more apical LV were larger and more spherically shaped. Both the distance to the vortex core and the vortex area correlated significantly with LV end-diastolic volume (r = 0.66 and 0.73), LVEF (r = -0.74 and -0.68), LV sphericity index (r = -0.60 and -0.65), and peak filling rate (r = -0.61 and -0.64), respectively (P < 0.01). The intra-LV vortices developed during the systolic phase in 10 cases. In those, some of the particles at the apical LV rotated within the LV, whereas in patients with preserved LV function, all of the particles were directed straight to the ascending aorta with accelerated flow velocity (256.8 ± 120.2 cm/s vs. 414.3 ± 88.2 cm/s, P < 0.01). CONCLUSION: Vortex formation during the diastolic phase may be critical for both LV filling and ejection. 4D-Flow showed the 3D alterations of intra-LV flow dynamics by LV dilatation and dysfunction in a noninvasive and comprehensive manner. J. Magn. Reson. Imaging 2016;44:1493-1503.

Near-Infrared Diffuse Optical Imaging for Early Prediction of Breast Cancer Response to Neoadjuvant Chemotherapy: A Comparative Study Using 18F-FDG PET/CT.

UNLABELLED: Diffuse optical spectroscopic imaging (DOSI) is used as an indicator of tumor blood volume quantified by tissue hemoglobin concentrations. We aimed to determine whether early changes in tumor total hemoglobin (tHb) concentration can predict a pathologic complete response (pCR) to neoadjuvant chemotherapy in patients with operable breast cancer, and we compared the predictive value of pCR between DOSI and (18)F-FDG PET combined with CT. METHODS: Of the 100 patients enrolled, 84 patients were prospectively evaluated for primary objective analysis. Sixty-four of the patients underwent both sequential DOSI scans at baseline after their first and second chemotherapy courses and (18)F-FDG PET/CT at baseline and after their second chemotherapy course. The mean tHb (tHbmean) concentration and SUVmax of the lesion were measured using DOSI and (18)F-FDG PET/CT, respectively, and the percentage change in tHbmean (∆tHbmean) and change in SUVmax (∆SUVmax) were calculated. We compared the diagnostic performances of DOSI and (18)F-FDG PET/CT for predicting pCR via the analysis of the receiver-operating-characteristic curves. RESULTS: pCR was achieved in 16 patients, and neoadjuvant chemotherapy caused a significant reduction of ∆tHbmean in pCR compared with non-pCR after the 2 chemotherapy courses. When the tentative ∆tHbmean cutoff values after the first and second courses were used, the ability to predict pCR was as follows: 81.2% sensitivity/47.0% specificity and 93.7% sensitivity/47.7% specificity, respectively. Comparison of the diagnostic performances of DOSI and (18)F-FDG PET/CT revealed areas under the curve of 0.69 and 0.75 of ∆tHbmean after the first and second courses, respectively, which were lower than those of ∆SUVmax (0.90). CONCLUSION: DOSI predicted pCR in patients with breast cancer with moderate accuracy. The diagnostic performance of DOSI was inferior to that of the early metabolic response as monitored by (18)F-FDG PET/CT.

Effect of the chest wall on the measurement of hemoglobin concentrations by near-infrared time-resolved spectroscopy in normal breast and cancer.

BACKGROUND: Optical imaging and spectroscopy using near-infrared light have great potential in the assessment of tumor vasculature. We previously measured hemoglobin concentrations in breast cancer using a near-infrared time-resolved spectroscopy system. The purpose of the present study was to evaluate the effect of the chest wall on the measurement of hemoglobin concentrations in normal breast tissue and cancer. METHODS: We measured total hemoglobin (tHb) concentration in both cancer and contralateral normal breast using a near-infrared time-resolved spectroscopy system in 24 female patients with breast cancer. Patients were divided into two groups based on menopausal state. The skin-to-chest wall distance was determined using ultrasound images obtained with an ultrasound probe attached to the spectroscopy probe. RESULTS: The apparent tHb concentration of normal breast increased when the skin-to-chest wall distance was less than 20 mm. The tHb concentration in pre-menopausal patients was higher than that in post-menopausal patients. Although the concentration of tHb in cancer tissue was statistically higher than that in normal breast, the contralateral normal breast showed higher tHb concentration than cancer in 9 of 46 datasets. When the curves of tHb concentrations as a function of the skin-to-chest wall distance in normal breast were applied for pre- and post-menopausal patients separately, all the cancer lesions plotted above the curves. CONCLUSIONS: The skin-to-chest wall distance affected the measurement of tHb concentration of breast tissue by near-infrared time-resolved spectroscopy. The tHb concentration of breast cancer tissue was more precisely evaluated by considering the skin-to-chest wall distance.

Hepatic Relaxation Times from Postmortem MR Imaging of Adult Humans.

PURPOSE: To measure T1 and T2 values of hepatic postmortem magnetic resonance (PMMR) imaging. MATERIALS AND METHODS: We performed hepatic PMMR imaging of 22 deceased adults (16 men, 6 women; mean age, 56.3 years) whose deaths were for reasons other than liver injury or disease at a mean of 27.7 hours after death. Before imaging, the bodies were kept in cold storage at 4°C (mean rectal temperature, 17.6°C). We measured T1 and T2 values in the liver at two sites (the anterior segment of the right lobe and the lateral segment of the left lobe). We also investigated the influence of the body temperature and postmortem interval on T1 and T2 values. RESULTS: In the anterior segment of the right lobe and the lateral segment of the left lobe, T1 values of PMMR imaging were 524 ± 112 ms and 472 ± 104 ms (mean ± standard deviation), respectively; while T2 values were 42 ± 6 ms and 43 ± 8 ms, respectively. T1 and T2 values did not differ significantly between the two sites (P ≧ 0.05). Regarding temperature, the T2 values of hepatic PMMR imaging were linearly correlated with the body temperature, but the T1 values were not. The T1 and T2 values of the two sites in the liver did not correlate with the postmortem interval. CONCLUSION: Reduction in body temperature after death is considered to induce T1 and T2 value changes in the liver on PMMR imaging.

Feasibility of magnetic resonance elastography for the pancreas at 3T.

PURPOSE: 1) To assess the usefulness of an elastic belt bracing the upper abdomen for reducing the miscalculated areas of the pancreas on 3.0T magnetic resonance elastography (MRE); 2) to test whether MRE can detect difference of stiffness between normal pancreas and the focal pancreatic diseases. MATERIALS AND METHODS: Using an initial eight normal volunteers, miscalculated areas were compared between MRE with the elastic belt and without the belt on 3.0T MRI. Then, using the belt, MRE of the normal pancreas was measured using 14 volunteers and 11 patients with focal pancreatic lesions. RESULTS: The median (95% confidence interval [CI]) percentages of correctly calculated areas were 57.4% (32.9-63.0) with the elastic belt and 35.3% (11.4-60.4) without the belt (P = 0.0078). The stiffness of each pancreatic segment of the normal volunteers (mean ± SE) was 2.37 ± 0.16 kPa for the head, 2.46 ± 0.17 kPa for the body, and 2.58 ± 0.26 kPa for the tail. The stiffness of seven pancreatic cancers was 6.06 ± 0.49 kPa, which was higher than the overall pancreatic stiffness of the normal volunteers (2.47 ± 0.11 kPa, P < 0.0001). Stiffness of the pancreatic lesions in the head of 6.03 ± 0.42 kPa, body of 5.57 ± 0.82 kPa, and tail of 5.9 ± 1.9 kPa were also higher than those of corresponding segments of the normal volunteers (P = 0.0011, 0.0029, and 0.029, respectively). CONCLUSION: With the elastic belt, miscalculation of the pancreatic stiffness was reduced. MRE showed differences of stiffness between normal pancreas and pancreatic lesions.

Gel phantom study of a cryosurgical probe with a thermosiphon effect and liquid nitrogen-cooled aluminum thermal storage blocks.

Cryosurgery is a minimally invasive treatment for certain types of cancers. Argon-based cryosurgical devices are available at present, however a large compressed gas cylinder with the pressure of 300 atmospheres is needed. To overcome these drawbacks, we developed a new cryosurgical probe measuring about 50 cm in length with separate lumens inside for liquid and gaseous ethylene to be used as a thermosiphon and liquid nitrogen-cooled aluminum thermal storage blocks. The probe needle was 8 cm in length and 3 mm in outer diameter. To investigate the freezing capabilities of our new cryosurgical system we inserted the needle 5cm into a poly-acrylamide gel phantom warmed to 36.5 ℃. Thermal storage blocks made of aluminum, cooled at -196 ℃ in liquid nitrogen, were attached to the condenser of the probe and replaced with thermal storage blocks every 4 to 5 minutes to compensate for warming. We took digital camera images of the ice ball at the needle and measured the temperature in certain locations of the cryoprobe. Ice ball formation started at one minute after cooling. The sizes (longest diameter × minimum diameter) at 10, 20 and 30 minutes after the start of the procedure were 4.5×2.1, 4.5×3.1 and 4.6×3.7 cm, respectively. During the procedure the minimum temperature of the condenser was -85 ℃ and the needle was -65 ℃. This newly developed compact cryosurgical probe with thermosiphon effect and cooled thermal storage blocks created an ice ball that can be used for cryosurgery within 20 minutes.

MR-based computational fluid dynamics with patient-specific boundary conditions for the initiation of a sidewall aneurysm of a basilar artery.

We performed 3-dimensional cine phase-contrast magnetic resonance-based computational fluid dynamics for a basilar artery that developed a sidewall aneurysm over a 25-month period. There was an area with high gradient oscillatory number in the location of the future aneurysm ostium and an area with high wall shear stress (WSS) and high spatial WSS gradient at the distal edge of the future aneurysm. These could be biomarkers for development of intracranial aneurysms.

Hemodynamic assessment in a child with renovascular hypertension using time-resolved three-dimensional cine phase-contrast MRI.

Renovascular hypertension (RVH) is an important cause of hypertension in children. It is essential to assess the hemodynamics of RVH lesions in detail. We herein report the case of a 9-year-old female with RVH caused by left renal artery stenosis in which the hemodynamics of the lesions were assessed with time-resolved three-dimensional cine phase-contrast MRI (3D cine PC MRI) with a vastly undersampled 3D radial projection imaging trajectory before and after percutaneous transluminal renal angioplasty (PTRA). The utility of 3D cine PC MRA for diagnosing RVH and evaluating the renal blood flow pre- and post-PTRA is presented.