Comparison of the outcomes of Pneumocystis jirovecii pneumonia in rheumatoid arthritis patients treated with and without biologics.

BACKGROUND: To investigate the outcomes of Pneumocystis jirovecii pneumonia (PCP) between patients with rheumatoid arthritis (RA) treated with and without biologics before PCP onset. PATIENTS AND METHODS: We retrospectively included rheumatoid arthritis (RA) patients with PCP treated with and without biologics before PCP onset. The primary endpoints were 30-day and 180-day survival rates, and the secondary endpoint was severe PCP, including in-hospital death, intensive care unit admission, and requirement of respiratory support during hospitalization. RESULTS: Eighty-two patients were enrolled in this study, including the Biologics group (n = 39) and Non-Biologics group (n = 43). There were no significantly differences in the 30-day and 180-day survival rates and severe PCP rate in the Biologics group and the Non-Biologics group before and after adjusting the patient characteristics. Kaplan-Meier survival curves for death showed no significantly differences between the Biologics and Non-Biologics groups. Cox regression hazard analysis revealed that the average daily prednisolone dose within 90 days before PCP onset was weakly associated with mortality after PCP. CONCLUSIONS: Biologic use before PCP onset did not increase the severity and mortality of PCP compared to non-biologics use in patients with RA.

Time resolved DCE-MRI of the kidneys: Evaluation of the renal vasculatures and tumors using F-DISCO with and without compressed sensing in normal and wide-bore 3T systems.

Dynamic contrast-enhanced MR imaging (DCE-MRI) has been widely used for the evaluation of renal arteries. This method is also useful for tumor and renal parenchyma characterization. The very fast MRI may provide stable and precise information regarding vasculature and soft tissues. The purpose of this study was to evaluate the ability of DCE-MRI to assess renal vasculatures and tumor perfusions using Differential subsampling with Cartesian ordering with spectrally selected inversion recovery with adiabatic pulses (F-DISCO) with and without compressed sensing (CS) in normal and wide-bore 3T systems. Fifty-one patients who underwent DCE-MRI using F-DISCO with or without CS for evaluation of renal or adrenal regions were included. Image quality, artifacts, fat saturation, and selective visual recognition of renal vasculatures were assessed by using a 5-point scale. Tumor recognition was verified by using a 5-point scale of confidence level. Signal intensities of each structure were also measured. In all cases, the temporal resolution of each phase for DCE-MRI was 1.9 to 2.0 seconds. Image quality, artifacts, fat saturation, and selective visual recognition of vasculatures were all acceptable (mean score 4.2-4.9). The selective visualization of renal arteries and veins was successfully accomplished (mean score 4.0-4.9). Contrast media perfusion for renal vasculature, renal parenchyma, and tumors was also recognized. DCE-MRI for the evaluation of renal vasculatures and tumors using F-DISCO with or without CS can be performed with high temporal and spatial resolutions in normal and wide-bore 3T systems. This information can be obtained in a stable fashion throughout the dynamic contrast study. CS can additionally provide benefits that the total imaging time may be shorter than without CS.

MRI-based radiomics analysis for differentiating phyllodes tumors of the breast from fibroadenomas.

OBJECTIVES: To evaluate the diagnostic performance of MRI-based radiomics model for differentiating phyllodes tumors of the breast from fibroadenomas. METHODS: This retrospective study included 88 patients (32 with phyllodes tumors and 56 with fibroadenomas) who underwent MRI. Radiomic features were extracted from T2-weighted image, pre-contrast T1-weighted image, and the first-phase and late-phase dynamic contrast-enhanced MRIs. To create stable machine learning models and balanced classes, data augmentation was performed. A least absolute shrinkage and selection operator (LASSO) regression was performed to select features and build the radiomics model. A radiological model was constructed from conventional MRI features evaluated by radiologists. A combined model was constructed using both radiomics features and radiological features. Machine learning classifications were done using support vector machine, extreme gradient boosting, and random forest. The area under the receiver operating characteristic (ROC) curve (AUC) was computed to assess the performance of each model. RESULTS: Among 1070 features, the LASSO logistic regression selected 35 features. Among three machine learning classifiers, support vector machine had the best performance. Compared to the radiological model (AUC: 0.77 ± 0.11), the radiomics model (AUC: 0.96 ± 0.04) and combined model (0.97 ± 0.03) had significantly improved AUC values (both p < 0.01) in the validation set. The combined model had a relatively higher AUC than that of the radiomics model in the validation set, but this was not significantly different (p = 0.391). CONCLUSIONS: Radiomics analysis based on MRI showed promise for discriminating phyllodes tumors from fibroadenomas. KEY POINTS: • The radiomics model and the combined model were superior to the radiological model for differentiating phyllodes tumors from fibroadenomas. • The SVM classifier performed best in the current study. • MRI-based radiomics model could help accurately differentiate phyllodes tumors from fibroadenomas.

Factors Associated with Pneumocystis jirovecii Pneumonia in Patients with Rheumatoid Arthritis Receiving Methotrexate: A Single-center Retrospective Study.

Objective To investigate the risk factors for the development of Pneumocystis jirovecii pneumonia (PCP) in patients with rheumatoid arthritis (RA) undergoing methotrexate (MTX) therapy. Methods This single-center retrospective cohort study included consecutive patients with RA who received MTX for at least one year. The study population was divided into PCP and non-PCP groups, depending on the development of PCP, and their characteristics were compared. We excluded patients who received biologic disease-modifying anti-rheumatic drugs (DMARDs), Janus kinase inhibitors, and anti-PCP drugs for prophylaxis. Results Thirteen patients developed PCP, and 333 did not develop PCP. At the initiation of MTX therapy, the PCP group had lower serum albumin levels, a higher frequency of pulmonary disease and administration of DMARDs, and received a higher dosage of prednisolone (PSL) than the non-PCP group. A multivariate Cox regression analysis revealed that the concomitant use of PSL [hazard ratio (HR) 5.50, p=0.003], other DMARDs (HR 5.98, p=0.002), and serum albumin <3.5 mg/dL (HR 4.30, p=0.01) were risk factors for the development of PCP during MTX therapy. Patients with these risk factors had a significantly higher cumulative probability of developing PCP than patients who lacked these risk factors. Conclusion Clinicians should pay close attention to patients with RA who possess risk factors for the development of PCP during MTX therapy.

Experience using mTOR inhibitors for subependymal giant cell astrocytoma in tuberous sclerosis complex at a single facility.

BACKGROUND: Subependymal giant cell astrocytoma (SEGA) is occasionally seen in tuberous sclerosis complex (TSC). Two main options are currently available for treating SEGA: surgical resection or pharmacotherapy using mammalian target of rapamycin inhibitors (mTORi). We hypothesized that opportunities for surgical resection of SEGA would have reduced with the advent of mTORi. METHODS: We retrospectively reviewed the charts of patients treated between August 1979 and July 2020, divided into a pre-mTORi era group (Pre-group) of patients treated before November 2012, and a post-mTORi era group (Post-group) comprising patients treated from November 2012, when mTORi became available in Japan for SEGA. We compared groups in terms of treatment with surgery or mTORi. We also reviewed SEGA size, rate of acute hydrocephalus, recurrence of SEGA, malignant transformation and adverse effects of mTORi. RESULTS: In total, 120 patients with TSC visited our facility, including 24 patients with SEGA. Surgical resection was significantly more frequent in the Pre-group (6 of 7 patients, 86 %) than in the Post-group (2 of 17 patients, 12 %; p = 0.001). Acute hydrocephalus was seen in 1 patient (4 %), and no patients showed malignant transformation of SEGA. The group treated using mTORi showed significantly smaller SEGA compared with the group treated under a wait-and-see policy (p = 0.012). Adverse effects of pharmacotherapy were identified in seven (64 %; 6 oral ulcers, 1 irregular menstruation) of the 11 patients receiving mTORi. CONCLUSIONS: The Post-group underwent surgery significantly less often than the Pre-group. Since the treatment option to use mTORi in the treatment of SEGA in TSC became available, opportunities for surgical resection have decreased in our facility.

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.

Association between diffuse cerebral MRI lesions and the occurrence and intractableness of West syndrome in tuberous sclerosis complex.

OBJECTIVE: We aimed to clarify the association between magnetic resonance imaging (MRI)-lesion patterns, including cortices and white matters, and the development, occurrence, and intractableness of West syndrome in patients with tuberous sclerosis complex (TSC), using visual analysis. METHODS: We collected data for 44 patients with TSC who had undergone brain MRI and developmental evaluation after the ages of 2 and 3 years, respectively. Fluid-attenuated inversion recovery (FLAIR) and T1-weighted images were used to analyze the number of cyst-like tubers, the number of cyst-like subcortical lesions, and the presence of diffuse lesions involving the cortices and white matter. RESULTS: Developmental delays were observed in 28 patients. Nineteen patients had a history of West syndrome. Cyst-like tubers (range: 1-10), cyst-like subcortical lesions (range: 1-4), and diffuse lesions (range: 1-6 areas) were observed in 15, 9, and 14 patients, respectively. In the univariate analyses, all MRI findings were associated with development and/or history of West syndrome. However, in the multivariate analyses, only the diffuse lesion was associated with severe development (p = 0.003) and history of West syndrome (p = 0.012). In the subanalysis of patients with West syndrome, the diffuse lesions were also associated with pharmacological intractableness. Patients with diffuse lesions had a history of West syndrome with sensitivity of 68% and specificity of 96%. Patients with two or more areas of diffuse lesions had history of pharmacologically intractable West syndrome with sensitivity of 89% and specificity of 91%. CONCLUSIONS: Diffuse lesions may help to predict the poor neurological outcomes in patients with TSC.

Unexpectedly Smaller Artifacts of 3.0-T Magnetic Resonance Imaging than 1.5 T: Recommendation of 3.0-T Scanners for Patients with Magnet-Resistant Adjustable Ventriculoperitoneal Shunt Devices.

BACKGROUND: Magnetic resonance imaging (MRI) artifacts of adjustable shunt devices are thought to be similar to metal clip artifacts, in that they are larger with higher field strength scanners. We have published several reports about the artifacts of new MRI-resistant adjustable shunt devices, and we found a case in which a 3.0-T scanner showed smaller artifacts than the 1.5-T scanner. We aimed to clarify whether this claim is true or not. METHODS: Under permission of our institutional Ethical Committee, 2 volunteers underwent imaging studies using 3.0-T and 1.5-T scanners from GE, Siemens, and Philips. Four MRI-resistant adjustable shunt devices-proGAV2.0 (Miethke), Codman Certas Plus (Johnson & Johnson), Polaris (Sophysa), and Strata MR valve (Medtronic)-were fixed on the left temporal scalp. Routine MRI images, including T1-and T2-weighted imaging, fluid-attenuated inversion recovery, diffusion-weighted imaging (DWI), and magnetic resonance angiography (MRA), were obtained. We also compared artifacts between a 3.0-T scanner and a-1.5 T scanner in 4 patients. RESULTS: The 3.0 T-scanners showed smaller artifacts than the 1.5-T scanners on DWI and MRA images for all shunt devices and scanners. In the other sequences, the results depended on the MRI scanner manufacturer; however, the GE 3.0-T scanner showed smaller artifacts in every sequence. This was also true in the 4 clinical cases. CONCLUSIONS: A 3.0-T scanner is recommended over a 1.5-T scanner for patients with MRI-resistant adjustable shunt devices in the diagnosis of acute ischemic condition or when using GE scanners.

Establishment of a Regional Interdisciplinary Medical System for Managing Patients with Tuberous Sclerosis Complex (TSC).

Tuberous sclerosis complex (TSC) is an autosomal dominant inherited disease characterized by lesions that involve multiple organs. Interdisciplinary management at individual facilities needs to be coordinated to treat multiple organ systems. We hypothesized that the number of patients, opportunities for patients to undergo examinations, and opportunities for patients to be treated would increase after establishment of a TSC board (TB) in our hospital. From August 1979 to August 2017, 76 patients were studied. We established the TB in our hospital in 2014. We divided the patients into the pre-TB group and post-TB group. Patients consisted of 33 females and 43 males (mean age, 18.7 years; median age, 15 years). The follow-up period was 2 to 457 months (mean, 51.6 months; median, 24.5 months). Twenty-four patients were in the pre-TB group, and 52 were in the post-TB group. Regular follow-up (p < 0.001), younger age (p = 0.002), opportunities for patients to undergo examinations, opportunities for patients to receive neurological treatment (p < 0.001), and mammalian target of rapamycin (mTOR) inhibitor usage (p = 0.041) were significantly higher in the post-TB group. The radial relationship around the axis of TSC coordinators may be the key to interdisciplinary management of TSC.

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.

Double match of 18F-fluorodeoxyglucose-PET and iomazenil-SPECT improves outcomes of focus resection surgery.

BACKGROUND: When the results of electroencephalography (EEG), magnetic resonance imaging (MRI), and seizure semiology are discordant or no structural lesion is evident on MRI, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are important examinations for lateralization or localization of epileptic regions. We hypothesized that the concordance between interictal 2-[18F]fluoro-2-deoxy-D-glucose (18FDG)-PET and iomazenil (IMZ)-SPECT could suggest the epileptogenic lobe in patients with non-lesional findings on MRI. METHOD: Fifty-nine patients (31 females, 28 males; mean age, 29 years; median age, 27 years; range, 7-56 years) underwent subdural electrode implantation followed by focus resection. All patients underwent 18FDG-PET, IMZ-SPECT, and focus resection surgery. Follow-up was continued for ≥ 2 years. We evaluated surgical outcomes as seizure-free or not and analyzed correlations between outcomes and concordances of low-uptake lobes on PET, SPECT, or both PET and SPECT to the resection lobes. We used uni- and multivariate logistic regression analyses. RESULTS: In univariate analyses, all three concordances correlated significantly with seizure-free outcomes (PET, p = 0.017; SPECT, p = 0.030; both PET and SPECT, p = 0.006). In multivariate analysis, concordance between resection and low-uptake lobes in both PET and SPECT correlated significantly with seizure-free outcomes (p = 0.004). The odds ratio was 6.0. CONCLUSION: Concordance between interictal 18FDG-PET and IMZ-SPECT suggested that the epileptogenic lobe is six times better than each examination alone among patients with non-lesional findings on MRI. IMZ-SPECT and 18FDG-PET are complementary examinations in the assessment of localization-related epilepsy.

Setting pressure can change the size and shape of MRI artifacts caused by adjustable shunt valves: a study of the 4 newest models.

OBJECTIVE: Adjustable shunt valves that have been developed for the management of hydrocephalus all rely on intrinsically magnetic components, and artifacts with these valves on MRI are thus inevitable. The authors have previously reported that the shapes of shunt artifacts differ under different valve pressures with the proGAV 2.0 valve. In the present study the authors compared the size and shape of artifacts at different pressure settings with 4 new-model shunt valves. METHODS: The authors attached 4 new models of MRI-resistant shunt valve to the temporal scalp of a healthy volunteer: the proGAV 2.0; Codman Certas Plus; Polaris; and Strata MR. They set 3 different scales of pressures for each valve, depending on magnet orientation to the body axis. Artifacts were evaluated and compared among all valves on a 3.0-T GE scanner and 2 valves were also evaluated on a Philips scanner and a Siemens scanner. In-plane artifact sizes were evaluated as the maximum distance of the artifact from the expected scalp. RESULTS: The sizes and shapes of artifacts changed depending on valve pressure for all valves on the 3 different MRI scanners. Artifacts were less prominent on spin echo sequences than on gradient echo sequences. For diffusion-weighted imaging and time-of-flight MR angiography, the authors matched image numbers within the same sequence and compared appearances of artifacts. For all valves, the number of images affected by artifacts and the image number showing the largest artifact differed among valve settings. CONCLUSIONS: Artifacts of all adjustable shunt valves showed gross changes corresponding to pressure setting. Not only the maximum distance of artifacts but also the shape changed significantly. The authors suggest that changing pressure settings offers one of the easiest ways to minimize artifacts on MRI.

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.

Magnetic resonance angiography of the aorta.

Magnetic resonance angiography (MRA) is capable of imaging arteries in the half to whole body by a single acquisition without a nephrotoxic contrast medium, and acquired images can be reconstructed into a specific cross-sectional view in an arbitrary directions. MRA is applicable for vessels non-reachable by a catheter approach, and collateral vessels can be fully visualized. Since MRA is minimally-invasive with no exposure to ionized radiation, it can be repeatedly applied for follow-up. However, there are also disadvantages: the temporal and spatial resolutions are inferior to those of X-ray angiography, and, at present, it cannot be used as a guide for intervention. Moreover, gadolinium administrations may cause NSF in patients who have lost renal function, as a new risk. Accordingly, strict consideration is required for an indication of its application. Development of non-contrast MRA and evaluation of the wall itself may draw more attention in the future. Plaque imaging is being routinely performed nowadays, and the measurement of vascular wall shear stress, which has a close association with arteriosclerosis, may become possible by utilizing the time-resolved phase-contrast method capable of measuring the time-resolved velocity vectors of blood flow throughout the body. (*English Translation of J Jpn Coll Angiol, 2009, 49: 503-516.).

T2-weighted MRI of rectosigmoid carcinoma: comparison of respiratory-triggered fast spin-echo, breathhold fast-recovery fast spin-echo, and breathhold single-shot fast spin-echo sequences.

PURPOSE: To compare the abilities of T2-weighted (T2W) imaging using respiratory-triggered fast spin-echo (RT-FSE), breathhold fast-recovery FSE (BH-FRFSE), and BH single-shot FSE (BH-SSFSE) sequences without an endorectal coil to detect rectosigmoid carcinomas. MATERIALS AND METHODS: Forty patients (stage: pT0, 1; pTis-2, 15; pT3-4, 24) were included in the study. All examinations were performed on a 1.5T magnet with a phased-array coil and the patients were studied in the prone position with per-anal air injection. Qualitative and quantitative evaluations were performed. RESULTS: Motion artifact was the most prominent with the RT-FSE sequence, and the least prominent with the BH-SSFSE sequence. Scores for depiction of the rectal wall layer, tumor recognition, and overall image quality were the highest with the BH-FRFSE sequence. On the basis of a receiver operating characteristic (ROC) analysis, the detection rate of tumor invasion through the rectal wall was higher with the BH-FRFSE sequence (Az = 0.9077) than with the RT-FSE (Az = 0.7762, p < 0.05) or BH-SSFSE (Az = 0.8602) sequence. Tumor-to-fat contrast was highest with the BH-FRFSE sequence (P < 0.017). CONCLUSION: The BH-FRFSE sequence may be the first choice for rectosigmoid T2W imaging in the prone position with per-anal air injection for patients who can hold their breath stably.

Magnetic resonance cholangiopancreatography: comparison of respiratory-triggered three-dimensional fast-recovery fast spin-echo with parallel imaging technique and breath-hold half-Fourier two-dimensional single-shot fast spin-echo technique.

PURPOSE: The aim of this study was to compare magnetic resonance cholangiopancreatography (MRCP) using respiratory-triggered (resp) three-dimensional Fourier transformation (3D) fast-recovery fast spin echo (FR-FSE) sequence with array spatial sensitivity technique (ASSET) for visualization of the pancreatobiliary system with breath-hold single thick-section and multiple thin-section MRCP using 2D single shot FSE (SSFSE) sequences. MATERIALS AND METHODS: Forty patients underwent MRCP for evaluation of pancreatobiliary abnormalities in a 1.5-T magnet. Imaging time for resp 3D FR-FSE was recorded. The ghosting and blurring artifacts, overall image quality, and delineation of the pancreatobiliary ducts were evaluated using a five-point scale. RESULTS: On multisection 2D SSFSE source images, there were the least ghosting artifacts (4.9 +/- 0.3, P < 0.05). Ghosting (3.4 +/- 0.6, P < 0.05) and blurring (4.4 +/- 0.8; P < 0.05) artifacts were the most prominent on resp 3D FR-FSE. 3D FR-FSE MRCP provided the highest rating of overall image quality (4.3 +/- 0.8, P < 0.05) and delineation of third- and second-order branches of the hepatic ducts (2.9 +/- 1.6 for third-order branches and 3.9 +/- 1.3 for second-order branches, P < 0.05). Extrahepatic bile ducts, including upper and middle portions and cystic and pancreatic ducts, were also better seen with resp 3D FR-FSE MRCP than others. CONCLUSION: MRCP with resp 3D FR-FSE using ASSET can be routinely used for acquiring information from the pancreatobiliary system.

Intravenous injection of high and medium concentrations of computed tomography contrast media and related heat sensation, local pain, and adverse reactions.

OBJECTIVES: To evaluate the incidence of acute adverse reactions and degrees of heat sensation and local pain after intravenous injection of high and medium concentrations of iodinated contrast medium for computed tomography (CT). METHODS: A prospective study was performed involving 729 patients who underwent contrast CT scans. High-concentration (370 mgI/mL) and medium-concentration (300 mgI/mL) iodinated contrast medium was assigned to 342 patients (group H, aged 20-90 years, mean = 59.8 years) and to 387 patients (group M, aged 20-95 years, mean = 61.7 years), respectively. An injection rate of contrast medium (1, 2, or 4 mL/s) at a base volume of 2 mL/kg of body weight was selected according to the protocols for the evaluated diseases and regions. Each patient was assessed for heat sensation and local pain at the injection site using a visual analog scale (ranging from none for 0 to severe for 10). Acute adverse reactions were recorded when they occurred. RESULTS: There were no significant differences in patient background factors, including age, sex, history of prior adverse reactions, and allergies, between the 2 groups. The score for heat sensation was significantly higher in group H than in group M (4.46 +/- 2.44 vs. 3.44 +/- 2.45; P < 0.0001 for heat sensation). The data did not show a higher incidence of adverse reactions in group H than in group M (5 [1.46%] of 342 patients vs. 2 [0.52%] of 387 patients; P = 0.26) or a higher score for local pain in group H than in group M (0.98 +/- 1.70 vs. 0.88 +/- 1.49; P = 0.66), respectively. CONCLUSIONS: High and medium concentrations of iodinated contrast medium can be used for CT study with comparable safety profiles even though heat sensation produced by the high-concentration CM is greater than that produced by the medium-concentration CM.

MR imaging of primary malignant lymphoma of the pancreas.

Pancreatic lymphoma is rare and is usually found as a large pancreatic mass. We report the case of a small 2-cm pancreatic lymphoma in a 54-year-old woman that had its histological origin in the pancreatic parenchyma. The mass showed homogeneously high signal-intensity on T2-weighted images and low signal-intensity on T1-weighted images. The infiltrative nature and hypovascularity in early-phase dynamic contrast study without encasement of arteries and veins were well demonstrated by MR imaging and were consistent with malignant lymphoma.

Exophytic giant cavernous hemangioma of the liver with growing tendency.

Hepatic hemangioma is a common benign tumor, but its exophytic and expansile forms may be atypical. We report a case of exophytic hemangioma of the liver with a growing tendency, demonstrated using magnetic resonance imaging (MRI) and computed tomography (CT) combined with angiography.