Intra- and inter-operator reproducibility of US point shear-wave elastography in various organs: evaluation in phantoms and healthy volunteers.

PURPOSE: This study was conducted in order to assess the intra- and interoperator reproducibility of shear-wave speed (SWS) measurement on elasticity phantoms and healthy volunteers using ultrasound-based point shear-wave elastography. MATERIALS AND METHODS: This study was approved by the institutional review board. Two operators measured the SWS of five elasticity phantoms and seven organs (thyroid, lymph node, muscle, spleen, kidney, pancreas, and liver) of 30 healthy volunteers with 1.0-4.5 MHz convex (4C1) and 4.0-9.0 MHz linear (9L4) transducers. The phantom measurements were repeated ten times, while the volunteer measurements were performed five times each. Intra- and interoperator reproducibility was assessed. Interoperator reproducibility was also evaluated with the 95% Bland-Altman limits of agreement (LOA). RESULTS: In phantoms, all intraclass correlation coefficients (ICCs) were above 0.90 and the 95% LOA between the two operators were less than ± 18%. In volunteers, intraoperator ICCs were > 0.75 for all regions except the pancreas. Interoperator ICC was above 0.75 for the right lobe of the liver (depth 4 cm) and the kidney, but the 95% LOA was less than ± 25% only for the liver. CONCLUSION: Although excellent in phantoms, interoperator reproducibility was insufficient for all regions in the volunteers other than the right hepatic lobe at a depth of 4 cm. Clinicians should be aware of the 95% LOA when using SWS in patients. KEY POINTS: • Our phantom study indicated a high reproducibility for shear-wave speed (SWS) measurements with point shear-wave elastography (pSWE). • In volunteers, intraoperator reproducibility was generally high, but the interoperator reproducibility was not high enough except for the right hepatic lobe at 4 cm depth. • To evaluate interoperator reproducibility, the 95% limits of agreement (LOA) between operators should be considered in addition to the intraclass correlation coefficient (ICC).

Updated long-term outcomes after carbon-ion radiotherapy for primary renal cell carcinoma.

Long-term oncological outcomes for primary renal cell carcinoma (RCC) treated with carbon-ion radiotherapy (CIRT) are poorly understood. Patients with primary RCC were treated with 12 or 16-fraction CIRT at The Hospital of the National Institute of Radiological Sciences outside of clinical trials. Outcome data were pooled and retrospectively analyzed for toxicity, local control, and disease-free, cancer-specific, and overall survival. From 1997 to 2014, 19 RCC patients (11 with T1aN0M0, 4 with T1bN0M0, and 4 with inoperable advanced stage [T4N0M0, T3aN1M0, and T1aN0M1]) were treated with CIRT and followed up for a median of 6.6 (range, 0.7-16.5) years; 9 of these patients were inoperable because of comorbidities or advanced-stage disease. Diagnoses were confirmed by imaging in 11 patients and by biopsy in the remaining 8. In 4 of 5 patients with definitive renal comorbidities, including diabetic nephropathy, sclerotic kidney or solitary kidney pre-CIRT progressed to grade 4 chronic kidney disease (CKD). In contrast, the remaining 14 patients without definitive renal comorbidities did not progress to grade 3 or higher CKD. Furthermore, although 1 case of grade 4 dermatitis was observed, there were no other grade 3 or higher non-renal adverse events. Local control rate, and disease-free, cancer-specific, and overall survival rates at 5 years of all 19 patients were 94.1%, 68.9%, 100%, and 89.2%, respectively. This updated retrospective analysis based on long-term follow-up data suggests that CIRT is a safe treatment for primary RCC patients without definitive renal comorbidities pre-CIRT, and yield favorable treatment outcomes, even in inoperable cases.

Diffusion-tensor-based method for robust and practical estimation of axial and radial diffusional kurtosis.

OBJECTIVES: A new method that can estimate diffusional kurtosis image (DKI), estimated DKI (eDKI), parallel and perpendicular to neuronal fibres from greatly limited image data was designed to enable quick and practical assessment of DKI in clinics. The purpose of this study was to discuss the potential of this method for clinical use. METHODS: Fourteen healthy volunteers were examined with a 3-Tesla MRI. The diffusion-weighting parameters included five different b-values (0, 500, 1,500, 2,000 and 2,500 s/mm(2)) with 64 different encoding directions for each of the b-values. K values were calculated by both conventional DKI (convDKI) and eDKI from these complete data, and also from the data that the encoding directions were abstracted to 32, 21, 15, 12 and 6. Error-pixel ratio and the root mean square error (RMSE) compared with the standard were compared between the methods (Wilcoxon signed-rank test: P < 0.05 was considered significant). RESULTS: Error-pixel ratio was smaller in eDKI than in convDKI and the difference was significant. In addition, RMSE was significantly smaller in eDKI than in convDKI, or otherwise the differences were not significant when they were obtained from the same data set. CONCLUSION: eDKI might be useful for assessing DKI in clinical settings. KEY POINTS: • A method to practically estimate axial/radial DKI from limited data was developed. • The high robustness of the proposed method can greatly improve map images. • The accuracy of the proposed method was high. • Axial/radial K maps can be calculated from limited diffusion-encoding directions. • The proposed method might be useful for assessing DKI in clinical settings.

Safety and Efficacy of Single-Fraction Carbon-Ion Radiotherapy for Early-Stage Lung Cancer with Interstitial Pneumonia.

Patients with lung cancer complicated by interstitial pneumonia (IP) often lose treatment options early owing to acute exacerbation of IP concerns. Carbon-ion radiotherapy (CIRT) can provide superior tumor control and low toxicity at high dose concentrations. We conducted a retrospective analysis of the efficacy and tolerability of a single-fraction CIRT using 50 Gy for IP-complicated lung cancer. The study included 50 consecutive patients treated between April 2013 and September 2022, whose clinical stage of lung cancer (UICC 7th edition) was 1A:1B:2A:2B = 32:13:4:1. Of these, 32 (64%) showed usual interstitial pneumonia patterns. With a median follow-up of 23.5 months, the 3-year overall survival (OS), cause-specific survival, and local control rates were 45.0, 75.4, and 77.8%, respectively. The median lung V5 and V20 were 10.0 and 5.2%, respectively (mean lung dose, 2.6 Gy). The lung dose, especially lung V20, showed a strong association with OS (p = 0.0012). Grade ≥ 2 pneumonia was present in six patients (13%), including two (4%) with suspected grade 5. CIRT can provide a relatively safe and curative treatment for patients with IP-complicated lung cancer. However, IP increases the risk of severe radiation pneumonitis, and further studies are required to assess the appropriate indications.

Relationship between diffusion-weighted magnetic resonance imaging and histological tumor grading of hepatocellular carcinoma.

BACKGROUND: Intrahepatic and extrahepatic recurrence remains a significant problem for hepatocellular carcinoma (HCC). The aim of this study was to determine the usefulness of diffusion-weighted magnetic resonance imaging (DWI) for histological tumor grading and preoperative prediction of early HCC recurrence within 6 months of operation. METHODS: A total of 44 patients who had undergone hepatic resection for HCC (50 nodules) were reviewed retrospectively. DWI was performed within 30 days before hepatectomy, and apparent diffusion coefficients (ADCs) were measured using 2 methods: mean ADC and minimum-spot ADC. Relationships between ADCs and histological differentiation and between ADCs and early recurrence of HCC were analyzed. RESULTS: Mean ADC was significantly lower in poorly differentiated HCC (n=18, 1.07±0.15×10(-3) mm2/s) than in moderately differentiated HCC (n=29, 1.29±0.21×10(-3) mm2/s; P<.05). Minimum-spot ADC was significantly lower in poorly differentiated HCC (n=18, 0.69±0.19×10(-3) mm2/s) than in well-differentiated HCC (n=3, 1.15±0.10×10(-3) mm2; P<.01) or in moderately differentiated HCC (n=29, 0.98±0.18×10(-3) mm2/s; P<.0001). Of 34 patients who were able to be observed for >6 months after resection, 9 showed early recurrence. Minimum-spot ADC was significantly lower in patients with early recurrence (n=9, 0.64±0.24×10(-3) mm2/s) than in patients without early recurrence (n=25, 0.88±0.19×10(-3) mm2/s; P<.05). On multivariate analysis, minimum-spot ADC was a significant risk factor for early recurrence (P<.05). CONCLUSION: Quantitative measurement of ADC of HCC with magnetic resonance diffusion weighted imaging is a promising functional imaging tool in the prediction of histological grade and early recurrence before treatment.

Dual-Energy Computed Tomography-Based Iodine Concentration Estimation for Evaluating Choroidal Malignant Melanoma Response to Treatment: Optimization and Primary Validation.

Contrast-enhanced imaging for choroidal malignant melanoma (CMM) is mostly limited to detecting metastatic tumors, possibly due to difficulties in fixing the eye position. We aimed to (1) validate the appropriateness of estimating iodine concentration based on dual-energy computed tomography (DECT) for CMM and optimize the calculation parameters for estimation, and (2) perform a primary clinical validation by assessing the ability of this technique to show changes in CMM after charged-particle radiation therapy. The accuracy of the optimized estimate (eIC_optimized) was compared to an estimate obtained by commercial software (eIC_commercial) by determining the difference from the ground truth. Then, eIC_optimized, tumor volume, and CT values (80 kVp, 140 kVp, and synthesized 120 kVp) were measured at pre-treatment and 3 months and 1.5−2 years after treatment. The difference from the ground truth was significantly smaller in eIC_optimized than in eIC_commercial (p < 0.01). Tumor volume, CT values, and eIC_optimized all decreased significantly at 1.5−2 years after treatment, but only eIC_commercial showed a significant reduction at 3 months after treatment (p < 0.01). eIC_optimized can quantify contrast enhancement in primary CMM lesions and has high sensitivity for detecting the response to charged-particle radiation therapy, making it potentially useful for treatment monitoring.

Prenatal diagnosis of short-rib polydactyly syndrome type 3 (Verma-Naumoff type) by three-dimensional helical computed tomography.

We present a case of short-rib polydactyly syndrome (SRPs) type 3 in which accurate prenatal diagnosis was feasible using both ultrasonography and 3D-CT. SRP encompass a heterogeneous group of lethal skeletal dysplasias. However, the phenotypes overlap with those of nonlethal skeletal dysplasias (i.e. Ellis-van Creveld syndrome and Jeune syndrome). As accurate prenatal diagnosis of SRP is helpful for parents, we used 3D-CT in the early third trimester to examine a fetus suggested to have phenotypes of 'short-rib dysplasia group' on ultrasonography. 3D-CT showed mild modification of the vertebral bodies, small ilia with horizontal acetabula and triangular partial ossification defects, and subtle metaphyseal irregularities of the femora. These CT findings and an extensive literature search regarding the phenotypes of various diseases categorized as short-rib dysplasia group led to a correct prenatal diagnosis of SRP type 3. This case exemplified the usefulness of 3D-CT for the precise prenatal diagnosis of skeletal dysplasias.

Metastases in mediastinal and hilar lymph nodes in patients with non-small cell lung cancer: quantitative assessment with diffusion-weighted magnetic resonance imaging and apparent diffusion coefficient.

OBJECTIVE: To evaluate diffusion-weighted magnetic resonance (DW-MR) imaging for detection of metastases in lymph nodes by using quantitative analysis. METHODS: Seventy patients with non-small cell lung cancer were examined with DW and short inversion time inversion recovery (STIR) turbo-spin-echo MR imaging. Apparent diffusion coefficient of each lung cancer and lymph node was calculated from DW-MR images. Difference of the apparent diffusion coefficient in a lung cancer and a lymph node was calculated (D1). From STIR turbo-spin-echo MR images, ratios of signal intensity in a lymph node to that in a 0.9% saline phantom was calculated (lymph node-saline ratio [LSR1]). For quantitative analysis, the threshold value for a positive test was determined on a per node basis and tested for ability to enable a correct diagnosis on a per patient basis. Results of quantitative analyses of DW- and STIR-MR images were compared on a per patient basis with McNemar testing. RESULTS: Mean D1 in the lymph node group with metastases was lower than that in the group without metastases (P < 0.001). When an D1 of 0.24 x 10(-3) mm2/s was used as the positive test threshold, sensitivity, specificity, and accuracy were 69.2%, 100%, and 94.0%, respectively, on a per patient basis. There was no significant difference (P > 0.05) between quantitative analyses of DW-MR images and STIR-MR images. CONCLUSIONS: Quantitative analysis of DW-MR images enables differentiation of lymph nodes with metastasis from those without.

A clinical study of curative partial breast irradiation for stage I breast cancer using carbon ion radiotherapy.

BACKGROUND AND PURPOSE: Our institute initiated carbon ion radiotherapy research for patients with stage I breast cancer in April 2013. The purpose of this article is to evaluate the treatment outcome of cases treated outside clinical trial up to May 2020. MATERIALS AND METHODS: Eligibility criteria of the patients were having untreated stage I breast cancer and being unsuitable for operation for physical or mental reasons. The irradiated volume was defined as the gross tumor including intraductal components. The dose escalation study was initially conducted four times a week for a total of 52.8 Gy [relative biological efficacy (RBE)]. After confirming that adverse effects were within acceptable range, the total dose was increased to 60.0 Gy (RBE). RESULTS: Between April 2013 and November 2015, 14 cases were treated. The median follow up period was 61 months. No adverse toxicities were observed except for grade 1 acute skin reaction in 10 cases. The time required from carbonion radiotherapy to tumor disappearance was 3 months in 1 case, 6 months in 3 cases, 12 months in 4 cases, and 24 months in 5 cases. The third case developed local recurrence 6 months after radiotherapy. Twelve patients with luminal subtype received 5-year endocrine therapy. Thirteen of 14 tumors have been maintaining complete response with excellent cosmetic results. CONCLUSIONS: The time from carbon ion radiotherapy to tumor disappearance was longer than expected, but complete tumor disappearance was observed except for one high-grade case. With careful patient selection, carbonion radiotherapy in patients with stage I breast cancer is deemed effective and safe, and further research is recommended.

The Utility of Applying Various Image Preprocessing Strategies to Reduce the Ambiguity in Deep Learning-based Clinical Image Diagnosis.

PURPOSE: A general problem of machine-learning algorithms based on the convolutional neural network (CNN) technique is that the reason for the output judgement is unclear. The purpose of this study was to introduce a strategy that may facilitate better understanding of how and why a specific judgement was made by the algorithm. The strategy is to preprocess the input image data in different ways to highlight the most important aspects of the images for reaching the output judgement. MATERIALS AND METHODS: T2-weighted brain image series falling into two age-ranges were used. Classifying each series into one of the two age-ranges was the given task for the CNN model. The images from each series were preprocessed in five different ways to generate five different image sets: (1) subimages from the inner area of the brain, (2) subimages from the periphery of the brain, (3-5) subimages of brain parenchyma, gray matter area, and white matter area, respectively, extracted from the subimages of (2). The CNN model was trained and tested in five different ways using one of these image sets. The network architecture and all the parameters for training and testing remained unchanged. RESULTS: The judgement accuracy achieved by training was different when the image set used for training was different. Some of the differences was statistically significant. The judgement accuracy decreased significantly when either extra-parenchymal or gray matter area was removed from the periphery of the brain (P < 0.05). CONCLUSION: The proposed strategy may help visualize what features of the images were important for the algorithm to reach correct judgement, helping humans to understand how and why a particular judgement was made by a CNN.

Reference region extraction by clustering for the pharmacokinetic analysis of dynamic contrast-enhanced MRI in prostate cancer.

PURPOSE: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measures changes in the concentration of an administered contrast agent to quantitatively evaluate blood circulation in a tumor or normal tissues. This method uses a pharmacokinetic analysis based on the time course of a reference region, such as muscle, rather than arterial input function. However, it is difficult to manually define a homogeneous reference region. In the present study, we developed a method for automatic extraction of the reference region using a clustering algorithm based on a time course pattern for DCE-MRI studies of patients with prostate cancer. METHODS: Two feature values related to the shape of the time course were extracted from the time course of all voxels in the DCE-MRI images. Each voxel value of T1-weighted images acquired before administration were also added as anatomical data. Using this three-dimensional feature vector, all voxels were segmented into five clusters by the Gaussian mixture model, and one of these clusters that included the gluteus muscle was selected as the reference region. RESULTS: Each region of arterial vessel, muscle, and fat was segmented as a different cluster from the tumor and normal tissues in the prostate. In the extracted reference region, other tissue elements including scattered fat and blood vessels were removed from the muscle region. CONCLUSIONS: Our proposed method can automatically extract the reference region using the clustering algorithm with three types of features based on the time course pattern and anatomical data. This method may be useful for evaluating tumor circulatory function in DCE-MRI studies.

The Utility of a Convolutional Neural Network for Generating a Myelin Volume Index Map from Rapid Simultaneous Relaxometry Imaging.

PURPOSE: A current algorithm to obtain a synthetic myelin volume fraction map (SyMVF) from rapid simultaneous relaxometry imaging (RSRI) has a potential problem, that it does not incorporate information from surrounding pixels. The purpose of this study was to develop a method that utilizes a convolutional neural network (CNN) to overcome this problem. METHODS: RSRI and magnetization transfer images from 20 healthy volunteers were included. A CNN was trained to reconstruct RSRI-related metric maps into a myelin volume-related index (generated myelin volume index: GenMVI) map using the MVI map calculated from magnetization transfer images (MTMVI) as reference. The SyMVF and GenMVI maps were statistically compared by testing how well they correlated with the MTMVI map. The correlations were evaluated based on: (i) averaged values obtained from 164 atlas-based ROIs, and (ii) pixel-based comparison for ROIs defined in four different tissue types (cortical and subcortical gray matter, white matter, and whole brain). RESULTS: For atlas-based ROIs, the overall correlation with the MTMVI map was higher for the GenMVI map than for the SyMVF map. In the pixel-based comparison, correlation with the MTMVI map was stronger for the GenMVI map than for the SyMVF map, and the difference in the distribution for the volunteers was significant (Wilcoxon sign-rank test, P < 0.001) in all tissue types. CONCLUSION: The proposed method is useful, as it can incorporate more specific information about local tissue properties than the existing method. However, clinical validation is necessary.

Combination immunotherapy with radiation and CpG-based tumor vaccination for the eradication of radio- and immuno-resistant lung carcinoma cells.

Unmethylated cytosine-phosphorothioate-guanine containing oligodeoxynucleotides (CpG-ODN) is known as a ligand of toll-like receptor 9 (TLR9), which selectively activates type-1 immunity. We have already reported that the vaccination of tumor-bearing mice with liposome-CpG coencapsulated with model-tumor antigen, ovalbumin (OVA) (CpG + OVA-liposome) caused complete cure of the mice bearing OVA-expressing EG-7 lymphoma cells. However, the same therapy was not effective to eradicate Lewis lung carcinoma (LLC)-OVA-carcinoma. To overcome the refractoriness of LLC-OVA, we tried the combination therapy of radiation with CpG-based tumor vaccination. When LLC-OVA-carcinoma intradermally (i.d.) injected into C57BL/6 became palpable (7-8 mm), the mice were irradiated twice with a dose of 14 Gy at intervals of 24 h. After the second radiation, CpG + OVA-liposome was i.d. administered near the draining lymph node (DLN) of the tumor mass. The tumor growth of mice treated with radiation plus CpG + OVA-liposome was greatly inhibited and approximately 60% of mice treated were completely cured. Moreover, the combined therapy with radiation and CpG + OVA-liposome allowed the augmented induction of OVA-tetramer(+) LLC-OVA-specific cytotoxic T lymphocyte (CTL) in DLN of tumor-bearing mice. These results indicate that the combined therapy of radiation with CpG-based tumor vaccine is a useful strategy to eradicate intractable carcinoma.

Numerical Simulation Based on Individual Voxel Phantoms for a Sophisticated Evaluation of Internal Doses Mainly From 131I in Highly Exposed Workers Involved in the TEPCO Fukushima Daiichi NPP Accident.

As a response to the Tokyo Electric Power Company's Fukushima Daiichi nuclear power plant accident in 2011, seven TEPCO workers whose exposure doses were expected to be >250 mSv (a tentative dose limit stipulated by the Japanese central authority) attended Japan's National Institute for Radiological Sciences for additional internal dose measurements. The National Institute for Radiological Sciences examination revealed that these workers' internal doses came mainly from their intake of the radionuclide I during emergency operations. In this study, we performed numerical simulations based on individual volume-pixel (voxel) phantoms of six of the seven workers for a more sophisticated evaluation of their internal doses, taking into account the individual thyroid size and other specific parameters. The voxel phantoms were created from magnetic resonance imaging scan images. As a result, the individual thyroid volumes ranged from 6.5 to 28.2 cm and were considerably smaller than the reference value (~20 cm) adopted in the International Commission on Radiation Protection's dosimetric model for four of the six subjects. Compared to the original estimates of the thyroid absorbed dose, our preliminary evaluation revealed values that were increased by approximately 3-fold or decreased by 30% at maximum. A wide difference in the individual thyroid size would be one of the significant modifiers in the current dose estimation of subjects of the ongoing epidemiological study project. The present simulations also provided evidence that the direct thyroid measurements by the National Institute for Radiological Sciences to determine the workers' I thyroid contents were sufficiently accurate.

Prospective clinical trial of 12-fraction carbon-ion radiotherapy for primary renal cell carcinoma.

The aims of this study were to clarify the safety and efficacy of 12-fraction carbon-ion radiotherapy (CIRT) for primary renal cell carcinoma (RCC) and to confirm the recommended dose in a prospective clinical trial. This clinical trial was planned as a non-randomized, open-label, single-center phase I/II study of CIRT monotherapy. The incidence of acute adverse events was the primary endpoint. Dose-limiting toxicities (DLTs) were defined as grade ≥3 skin, gastrointestinal tract, or urologic adverse events. Based on the eligibility criteria, 8 patients with primary RCC, including 3 medically inoperable patients and 5 patients with tumors >4 cm, were enrolled. Of the 8 patients, 5 were treated with 66 Gy (relative biological effectiveness [RBE]), and subsequently, the dose was escalated to 72 Gy (RBE) for the remaining 3 patients. The median follow-up time was 43.1 months. No DLTs were observed at any dose level though the end of follow-up. Although 1 patient died of pneumonia 3 months after CIRT, which was determined to be unrelated to CIRT, no grade 3 or higher adverse events were observed, and both local control and cancer-specific survival rates were 100%. In conclusion, the safety and efficacy of CIRT hypofractionation using 12-fractions for the treatment of eligible RCC patients, including those with inoperable or tumor size >4 cm, were confirmed in this prospective trial, and a recommended dose of 72 Gy (RBE) was established.

Three-dimensional intrafractional motion of breast during tangential breast irradiation monitored with high-sampling frequency using a real-time tumor-tracking radiotherapy system.

PURPOSE: To evaluate the three-dimensional intrafraction motion of the breast during tangential breast irradiation using a real-time tracking radiotherapy (RT) system with a high-sampling frequency. METHODS AND MATERIALS: A total of 17 patients with breast cancer who had received breast conservation RT were included in this study. A 2.0-mm gold marker was placed on the skin near the nipple of the breast for RT. A fluoroscopic real-time tumor-tracking RT system was used to monitor the marker. The range of motion of each patient was calculated in three directions. RESULTS: The mean +/- standard deviation of the range of respiratory motion was 1.0 +/- 0.6 mm (median, 0.9; 95% confidence interval [CI] of the marker position, 0.4-2.6), 1.3 +/- 0.5 mm (median, 1.1; 95% CI, 0.5-2.5), and 2.6 +/- 1.4 (median, 2.3; 95% CI, 1.0-6.9) for the right-left, craniocaudal, and anteroposterior direction, respectively. No correlation was found between the range of motion and the body mass index or respiratory function. The mean +/- standard deviation of the absolute value of the baseline shift in the right-left, craniocaudal, and anteroposterior direction was 0.2 +/- 0.2 mm (range, 0.0-0.8 mm), 0.3 +/- 0.2 mm (range, 0.0-0.7 mm), and 0.8 +/- 0.7 mm (range, 0.1-1.8 mm), respectively. CONCLUSION: Both the range of motion and the baseline shift were within a few millimeters in each direction. As long as the conventional wedge-pair technique and the proper immobilization are used, the intrafraction three-dimensional change in the breast surface did not much influence the dose distribution.

Evaluation of the vascular supply to regions of the pancreas on CT during arteriography.

BACKGROUND: To evaluate the vascular supply of regions of the pancreas on computed tomography (CT) during arteriography with selective catheterization. METHODS: Thirteen patients were included. In each patient we performed conventional arteriography followed by CT during arteriography of each of the arteries: the superior mesenteric artery (SMA), gastroduodenal artery (GDA), and splenic artery (SPA). The regions of the pancreas that were most enhanced on CT during arteriography were considered to be the areas receiving the greatest infusion of blood from the selected artery. RESULTS: In all 13 patients, the uncinate process, the superior head, and the tail of the pancreas were predominantly supplied by the SMA, GDA, and SPA, respectively. The inferior head of the pancreas was predominantly supplied by the SMA in five patients, the GDA in nine patients, and both the SMA and GDA in one patient. The body of the pancreas was predominantly supplied by the SMA, GDA, and SPA in seven, two, and ten patients, respectively. CONCLUSIONS: The uncinate process predominantly infused by the SMA, the superior head by the GDA, and the tail by the SPA. The patterns of the vascular supply of the inferior head and the body vary from patient to patient.

Comparison of passive and scanning irradiation methods for carbon-ion radiotherapy for breast cancer.

The dose distribution of passive and scanning irradiation for carbon-ion radiotherapy for breast cancer was compared in order to determine the preferred treatment method. Eleven Japanese patients who received carbon-ion radiotherapy for breast cancer were retrospectively analyzed. The original clinical plans were used for the passive irradiation method, while the plans for the scanning irradiation method were more recently made. Statistical analysis suggested that there was no significant difference in superiority in terms of dose distribution between the passive and scanning irradiation methods. The present study found that the scanning irradiation method was not always superior to the passive method, despite a previous study having reported the superiority of scanning irradiation. The present result is considered to arise from characteristics of breast cancer treatment, such as the simplicity of the organ at risk and the shallow depth point of the target from the skin. It is noteworthy that the present study suggests that the passive irradiation method can provide better dose distribution, depending on the case.

Measuring shear-wave speed with point shear-wave elastography and MR elastography: a phantom study.

OBJECTIVES: To compare shear-wave speed (SWS) measured by ultrasound-based point shear-wave elastography (pSWE) and MR elastography (MRE) on phantoms with a known shear modulus, and to assess method validity and variability. METHODS: 5 homogeneous phantoms of different stiffnesses were made. Shear modulus was measured by a rheometer, and this value was used as the standard. 10 SWS measurements were obtained at 4 different depths with 1.0-4.5 MHz convex (4C1) and 4.0-9.0 MHz linear (9L4) transducers using pSWE. MRE was carried out once per phantom, and SWSs at 5 different depths were obtained. These SWSs were then compared with those from a rheometer using linear regression analyses. RESULTS: SWSs obtained with both pSWE as well as MRE had a strong correlation with those obtained by a rheometer (R2>0.97). The relative difference in SWS between the procedures was from -25.2% to 25.6% for all phantoms, and from -8.1% to 6.9% when the softest and hardest phantoms were excluded. Depth dependency was noted in the 9L4 transducer of pSWE and MRE. CONCLUSIONS: SWSs from pSWE and MRE showed a good correlation with a rheometer-determined SWS. Although based on phantom studies, SWSs obtained with these methods are not always equivalent, the measurement can be thought of as reliable and these SWSs were reasonably close to each other for the middle range of stiffness within the measurable range.

Physiologic change in flow velocity and direction of dural venous sinuses with respiration: MR venography and flow analysis.

BACKGROUND AND PURPOSE: Blood flow of the internal jugular vein and intracranial venous sinuses is affected by respiratory state. The purpose of this study was to clarify the changes in flow velocity and direction and signal intensities of sigmoid sinuses on phase-contrast (PC) MR images obtained with regular breathing and with deep inspiratory breath holding. METHODS: One hundred seven subjects without venous sinus abnormality were studied. Coronal 2D PC MR venography and axial 2D PC images with peripheral pulse gating were acquired with a 1.5-T MR unit, during regular breathing and deep inspiratory breath holding. The signal intensity changes of bilateral sigmoid sinuses on MR venograms and the changes of flow velocity and direction on the axial 2D PC images were analyzed. RESULTS: Breath holding decreased signal intensities of the right and left sigmoid sinuses on MR venograms in 57 (53.3%) and 36 (33.6%) subjects, respectively. Increased signal intensity was observed in 12 (11.2%) and 33 (30.8%) subjects, respectively. In the flow analysis, retrograde flow was detected at the left sigmoid sinus in four subjects (3.7%) during regular breathing, which was normalized by breath holding. Flow velocities of the right and left sigmoid sinuses decreased during breath holding in 92 (86.0%) and 70 (65.4%) subjects, and increased in 15 (14.0%) and 37 (34.6%) subjects, respectively. CONCLUSION: The signal intensities of sigmoid sinuses were affected by breath holding in about 2/3 of the subjects. Breath-holding maneuver can be used to increase blood flow and signal intensities of dural venous sinuses on PC MR venograms.