Impact of visiting restrictions on Edinburgh postnatal depression scale screening scores at one month postpartum during the spread of COVID-19: a single-center case-control study in Japan.

BACKGROUND: This study aimed to evaluate whether "visiting restrictions" implemented due to the coronavirus disease 2019 (COVID-19) pandemic are a risk factor for postpartum depression using the Edinburgh Postnatal Depression Scale (EPDS). METHODS: This case-control study participants who gave birth during the spread of COVID-19 (COVID-19 study group) and before the spread of COVID-19 (control group). Participants completed the EPDS at 2 weeks and 1 month after childbirth. RESULTS: A total of 400 cases (200 in each group) were included in this study. The EPDS positivity rate was significantly lower with visiting restrictions than without (8.5% vs.18.5%, p = 0.002). Multivariate analysis of positive EPDS screening at the 1st month checkup as the objective variable revealed that visiting restrictions (odds ratio (OR): 0.35, 95% confidence interval (CI): 0.18-0.68), neonatal hospitalization (OR: 2.17, 95% CI: 1.08-4.35), and prolonged delivery (OR: 2.87, 95% CI: 1.20-6.85) were factors associated with an increased risk of positive EPDS screening. CONCLUSION: Visiting restrictions on family during the hospitalization period for delivery during the spread of COVID-19 pandemic did not worsen EPDS screening scores 1 month postpartum, but stabilized the mental state of some mothers.

Effect of Devised Simultaneous Physical Function Improvement Training and Posture Learning Exercises on Posture.

Poor posture in young adults and middle-aged people is associated with neck and back pain which are among the leading causes of disability worldwide. Training posture maintenance muscles and learning about ideal posture are important for improving poor posture. However, the effect of using both approaches simultaneously has not been verified, and it is unclear how long the effects persist after the intervention. Forty female university students were randomly and evenly assigned to four groups: physical function improvement training, posture learning, combination, and control groups. Four weeks of intervention training was conducted. Postural alignment parameters were obtained, including trunk anteroposterior inclination, pelvic anteroposterior inclination, and vertebral kyphosis angle. Physical function improvement training for improving crossed syndrome included two types of exercises: "wall-side squatting" and "wall-side stretching". The posture learning intervention consisted of two types of interventions: "standing upright with their back against the wall" and "rolled towel". A multiple comparison test was performed after analysis of covariance to evaluate the effect of each group's postural change intervention on postural alignment. Only the combination group showed an effective improvement in all posture alignments. However, it was found that a week after the 4-week intervention, the subjects' postures returned to their original state.

Effects of Tissue Flossing and Dynamic Stretching on Hamstring Muscles Function.

Tissue flossing aims to improve range of motion (ROM), reduce pain, and enhance injury prevention. However, evidence is lacking regarding its effects. Therefore, this study examined the effects of flossing on hamstring muscles function in comparison to dynamic stretching (DS). Seventeen healthy young men ([mean ± SD] age, 23.2 ± 1.1 years; height, 1.72 ± 0.08 m; body mass, 63.5 ± 9.3 kg) volunteered as subjects in this randomized crossover trial. The subjects received flossing, DS, and control interventions in random order at least 1 week apart to eliminate the influence of the previous intervention. Flossing involved passive twisting and active movement using a floss band (Sanctband COMPRE Floss Blueberry, Sanct Japan Co., Ltd.). DS was performed for 4 minutes in 30-second sets consisting of 15 repetitions of 2 seconds stretching. The following were measured before and after each intervention: straight leg raise (SLR) test, passive knee extension (KE) test, passive torque, passive stiffness, fascicle length in the biceps femoris long head as an indication of hamstring muscles flexibility, and maximal isometric knee flexion contraction, maximal eccentric knee extension/flexion contraction, rate of force development, and muscle activity. Flossing yielded significant improvements in the SLR test (mean difference in post-intervention changes between interventions: 5.4°, percentage change from pre- to post-value: 13.4%, p = 0.004), passive KE test (6.2°, 4.5%, p < 0.001), passive torque at end-ROM (3.8 Nm, 4.7%, p = 0.03), and maximal eccentric knee flexion contraction (14.9% body weight, 8.2%, p = 0.03) than control. Moreover, flossing yielded 2.1-fold greater improvements in the passive KE test (3.8°, 4.5%, p = 0.03) and yielded significant improvements in the maximal eccentric knee extension contraction (29.9% body weight, 13.8%, p = 0.02) than DS. Therefore, flossing on hamstring muscles is more beneficial than DS with respect to increasing ROM and muscle exertion.

Sports activity participation after curved periacetabular osteotomy for acetabular dysplasia.

BACKGROUND: Curved periacetabular osteotomy (CPO) was developed to treat acetabular dysplasia. Given that CPO can improve physical function in the early post-operative period, patients might be able to participate in sports activities post-operatively. Therefore, this study examined the post-operative sports activity participation and characteristics of acetabular dysplasia patients who have undergone CPO. METHODS: A total of 52 patients who underwent CPO for acetabular dysplasia were given a questionnaire on pre- and post-operative sports activities; 43 patients responded. We surveyed patients' sports activities, satisfaction, and physical function. Patients were divided according to whether they participated in sports activities after CPO. Physical function was compared before and after CPO. RESULTS: The pre- and post-operative sports activity participation rates were 55.8 and 72.1%, respectively. Patients mostly performed low-impact sports activities. Moreover, patients who participated in sports activities post-operatively had smaller pre-operative range of motion of hip flexion and returned to full weight bearing earlier. CONCLUSIONS: Among acetabular dysplasia patients who underwent CPO, 72.1% participated in sports activities post-operatively. Post-operatively, patients participated not only in low-impact sports activities, but also in high-impact ones. These findings might be useful for advising patients who are concerned about participating in sports activities after CPO.

[Validation Study of Analytical Method for Determination of Amnesic Shellfish Poison in Bivalves].

Amnesic shellfish poison (ASP) is regarded as one of the shellfish poison groups in the EU, though it is not subject to regulation in Japan. We have developed an analytical method of ASP based on the report by Hatfield et al. and other methods. Validation studies were carried out with certified compositional reference materials (CRM). Performance parameters were estimated based on 17 analytical results. The estimate of trueness was 97.5%, and the estimate of intralaboratory reproducibility (RSD) was 1.5%. The HorRat(r) value was 0.16. These performance parameters meet the criteria in the Codex Procedural Manual. Furthermore, internal quality control was performed by using the CRM. The action limits were set based on the performance parameters of the method. Most of the results of the internal quality control were within the action limit range. The results confirmed that the quality of the analyses was well maintained. The purpose of the analytical method is to confirm that the level of ASP in scallop is less than 4.6 mg/kg. The applicability of the analytical method to scallops was confirmed by using spiked samples.

Dosimetric analysis of upper gastrointestinal ulcer after carbon-ion radiotherapy for pancreatic cancer.

PURPOSE: The aim of this study was to clarify the incidence, clinical risk factors, and dose-volume relationship of upper gastrointestinal (GI) ulcer after carbon-ion radiotherapy (C-ion RT) for pancreatic cancer. MATERIALS AND METHODS: Fifty-eight pancreatic cancer patients were treated with C-ion RT from April 2014 to December 2015. The total dose was 55.2Gy (RBE) in 12 fractions. D2cm3 of GI tracts were restricted under 46Gy (RBE); RBE-weighted absorbed dose. The association between dosimetric parameters (V10-50, Dmax, D1cm3, D2cm3) and GI ulcer was examined using Spearman's correlation. The incidence of GI ulcer was compared between the two groups divided by the cutoff value. RESULTS: Twelve patients (21%) experienced gastric ulcer including only one (2%) grade 3 ulcer. There was no grade 4/5 toxicity or duodenal ulcer. V10-30 was significantly associated with gastric ulcer. The 1-year estimated risk of gastric ulcer for the determined cutoff values were 51% vs. 10% (V10, ⩾102cm(3) or less), 42% vs. 9% (V20, ⩾24cm(3) or less), 34% vs. 4% (V30, ⩾6cm(3) or less). CONCLUSIONS: The incidence of GI ulcer after C-ion RT was very low with the dose constraint of D2cm3 <46Gy (RBE). To further minimize the risk of GI ulcer, V10-30 should also be reduced.

Particle radiotherapy for prostate cancer.

Recent advances in external beam radiotherapy have allowed us to deliver higher doses to the tumors while decreasing doses to the surrounding tissues. Dose escalation using high-precision radiotherapy has improved the treatment outcomes of prostate cancer. Intensity-modulated radiation therapy has been widely used throughout the world as the most advanced form of photon radiotherapy. In contrast, particle radiotherapy has also been under development, and has been used as an effective and non-invasive radiation modality for prostate and other cancers. Among the particles used in such treatments, protons and carbon ions have the physical advantage that the dose can be focused on the tumor with only minimal exposure of the surrounding normal tissues. Furthermore, carbon ions also have radiobiological advantages that include higher killing effects on intrinsic radio-resistant tumors, hypoxic tumor cells and tumor cells in the G0 or S phase. However, the degree of clinical benefit derived from these theoretical advantages in the treatment of prostate cancer has not been adequately determined. The present article reviews the available literature on the use of particle radiotherapy for prostate cancer as well as the literature on the physical and radiobiological properties of this treatment, and discusses the role and the relative merits of particle radiotherapy compared with current photon-based radiotherapy, with a focus on proton beam therapy and carbon ion radiotherapy.

Differential distribution of lymphatic clearance between upper and lower regions of the lung.

BACKGROUND AND OBJECTIVE: Many lung diseases arise as the consequence of inhalational injury. When pathogenic materials are inhaled, it is possible that their clearance routes become the main focus of injury in the lung. Lymphatic clearance is important in the removal from the lung of small inhaled particles. The leak of toxic agents from the lymphatic flow potentially explains the topographic distribution of diffuse lung diseases triggered by inhaled materials, for example asbestosis. The aim of this study was to evaluate the differences in lymphatic distribution across various craniocaudal levels of the lung by using carbon dust deposition (CDD) as a tracing marker. METHODS: We evaluated 61 HE-stained slides of the normal lung area from 61 lobectomy specimens. The intensity of CDD was scored into five degrees (0-4) in bronchiolovascular (BV) areas and subpleural/septal (SP) areas per slide. The distribution was highlighted by subtraction scores of SP areas from those of bronchiolovascular areas. RESULTS: The subtraction scores of the upper lung area were significantly greater than those in the lower area, whereas there was no significant difference in scores by pulmonary lobes. CONCLUSIONS: Our results indicated that the main lymphatic clearance routes vary according to the craniocaudal levels, and are predominant in BV areas of the upper areas and in SP areas of the lower areas of the lung. This may explain the histological variations in anatomical distribution observed in the biopsy specimens of some diffuse lung diseases.

Insufficiency fractures after pelvic radiation therapy for uterine cervical cancer: an analysis of subjects in a prospective multi-institutional trial, and cooperative study of the Japan Radiation Oncology Group (JAROG) and Japanese Radiation Oncology Study Group (JROSG).

PURPOSE: To investigate pelvic insufficiency fractures (IF) after definitive pelvic radiation therapy for early-stage uterine cervical cancer, by analyzing subjects of a prospective, multi-institutional study. MATERIALS AND METHODS: Between September 2004 and July 2007, 59 eligible patients were analyzed. The median age was 73 years (range, 37-84 years). The International Federation of Gynecologic Oncology and Obstetrics stages were Ib1 in 35, IIa in 12, and IIb in 12 patients. Patients were treated with the constant method, which consisted of whole-pelvic external-beam radiation therapy of 50 Gy/25 fractions and high-dose-rate intracavitary brachytherapy of 24 Gy/4 fractions without chemotherapy. After radiation therapy the patients were evaluated by both pelvic CT and pelvic MRI at 3, 6, 12, 18, and 24 months. Diagnosis of IF was made when the patients had both CT and MRI findings, neither recurrent tumor lesions nor traumatic histories. The CT findings of IF were defined as fracture lines or sclerotic linear changes in the bones, and MRI findings of IF were defined as signal intensity changes in the bones, both on T1- and T2-weighted images. RESULTS: The median follow-up was 24 months. The 2-year pelvic IF cumulative occurrence rate was 36.9% (21 patients). Using Common Terminology Criteria for Adverse Events version 3.0, grade 1, 2, and 3 IF were seen in 12 (21%), 6 (10%), and 3 patients (5%), respectively. Sixteen patients had multiple fractures, so IF were identified at 44 sites. The pelvic IF were frequently seen at the sacroileal joints (32 sites, 72%). Nine patients complained of pain. All patients' pains were palliated by rest or non-narcotic analgesic drugs. Higher age (>70 years) and low body weight (<50 kg) were thought to be risk factors for pelvic IF (P=.007 and P=.013, Cox hazard test). CONCLUSIONS: Cervical cancer patients with higher age and low body weight may be at some risk for the development of pelvic IF after pelvic radiation therapy.

Retrospective analysis of contrast-enhanced computed tomographic findings related to obstructive shock due to ascending aortic dissection.

OBJECTIVE: The objective of this study was to evaluate contrastenhanced computed tomography findings related to obstructive shock due to ascending aortic dissection (AAD). METHODS: The computed tomography findings in 9 AAD patients with shock, 11 AAD patients without shock, and 18 control subjects were evaluated for (1) pericardial effusion, (2) diameter of the inferior vena cava, (3) periportal hypodensity, (4) retrograde reflux of contrast material, (5) aortic and visceral enhancement, and (6) other factors (peripancreatic edema, bowel thickening/dilatation). RESULTS: Patients with shock showed the highest ratio of pericardial effusion, periportal hypodensity, and retrograde reflux of contrast material; largest inferior vena cava diameter; stronger aortic enhancement in both the arterial and portal phases; lowered splenic and pancreatic enhancement in the arterial phase; and stronger visceral (especially adrenal) enhancement, except for the renal medulla in the portal phase. CONCLUSIONS: Computed tomography findings related to obstructive shock due to AAD reflected impaired diastolic filling, decreased cardiac output, and flow redistribution in visceral organs.

Narrowed petrous carotid canal detection for the early diagnosis of moyamoya disease.

PURPOSE: Patients with moyamoya disease (MMD) exhibit narrowed internal carotid arteries (ICAs) because the distal ends of the bilateral ICAs have become progressively stenosed, starting mainly in childhood. Accordingly, the petrous carotid canals in MMD patients are suspected to be more hypoplastic than those in control subjects. In this study, the diagnostic value of conventional computed tomography for MMD patients was retrospectively evaluated by comparing the caliber of the bilateral carotid canals in MMD patients with that in control subjects. MATERIALS AND METHODS: Thirty-five patients with MMD (15 males, 20 females; age range/average age: 6-71 / 26.1 years old) and age- and sex-matched control subjects underwent conventional head computed tomography. The maximal petrous carotid canal diameters of the two groups were measured and compared. RESULTS: The maximal petrous carotid canal diameter was significantly smaller in the moyamoya patients (mean +/- standard deviation [mm] = 4.70 +/- 0.61) than in the control subjects (5.62 +/- 0.61, p < 0.01). CONCLUSION: Conventional head computed tomography revealed narrowed petrous carotid canals in the MMD patients. This basic information could be utilized to screen patients who will require further examination, especially among those with underlying MMD.

MRI findings of mediastinal neurogenic tumors.

OBJECTIVE: The objective of this article is to review the clinical, pathologic, and MRI findings of mediastinal neurogenic tumors according to the three tumor origins: the peripheral nerves, sympathetic ganglia, and paraganglia. CONCLUSION: MRI findings reflect pathologic features of mediastinal neurogenic tumors. Integrating consideration of age and clinical findings of the patient, lesion location, and imaging findings is important in the diagnosis of mediastinal neurogenic tumors.

Aneurismal type of colorectal cancer: imaging characteristics of gastrointestinal endoscopy, computed tomography and magnetic resonance imaging.

BACKGROUND/AIMS: Only a few studies have investigated aneurismal large-intestinal malignant diseases. The present study reported five cases of aneurismal colon cancer that were experienced over 20 years. The present study aims to define the pathological and diagnostic imaging characteristics of aneurismal colon cancer. METHODOLOGY: A case series from a retrospective review of large-intestinal malignant tumors at Saga Medical School, Japan. Barium enema was performed in 876 patients with large-intestinal advanced cancer, which included five with aneurismal-type cancer. RESULTS: The characteristics of the 5 cases were as follows: (i) pathological findings were poorly differentiated adenocarcinoma without desmoplastic change or mucinous adenocarcinoma; (ii) a typical aneurismal type revealed by barium enema had a low elevated tumor edge without stenosis upon endoscopic examination; (iii) computed tomography showed low attenuation without enhancement of contrast material; and (iv) magnetic resonance imaging indicated high intensity in the T2-weighted images of mucinous adenocarcinoma. CONCLUSION: We revealed 5 cases of aneurismal colon cancer, which had characteristic pathological findings and diagnostic imaging, and poor prognosis.

High b-value diffusion-weighted MRI in differentiation between benign and malignant polypoid gallbladder lesions.

BACKGROUND: Several studies have reported the effectiveness of high b-value diffusion-weighted MR imaging (DWI) in the abdominal region, and have found that various malignant tumors may show high signal intensity on DWI, reflecting their high cellularity and/or their long relaxation time. The value of ADC measurement has also been documented for the diagnosis of several abdominal malignancies. PURPOSE: To retrospectively evaluate the usefulness of high b-value DWI in differentiating between benign and malignant polypoid gallbladder lesions. MATERIAL AND METHODS: The study population consisted of 10 benign (three hyperplastic polyps and seven adenomas) and 13 malignant (all adenocarcinomas) polypoid gallbladder lesions. DWI was evaluated by two observers. Qualitatively, the signal intensity of the lesions on DWI was visually evaluated and categorized as iso, high, or very high. Quantitatively, the ADC values of the lesions were measured from ADC maps. Statistical analysis was performed using a two-tailed Fisher's exact test and the Mann-Whitney test, respectively. RESULTS: Qualitative analysis revealed a statistical difference (P = 0.0041). Six of 10 benign lesions were categorized as iso, and the remaining four were categorized as high. In the 13 malignant lesions, one was categorized as iso, five as high, and seven as very high. The ADC values of the malignant lesions (1.34 ± 0.50 × 10(-3) mm(2)/sec) were significantly lower than those of the benign lesions (2.26 ± 0.44 × 10(-3) mm(2)/sec) (P = 0.00016). CONCLUSION: High b-value DWI may be useful for differentiating between benign and malignant polypoid gallbladder lesions by the visual assessment of DWI and ADC measurement.

Assessment of Moyamoya disease with 3.0-T magnetic resonance angiography and magnetic resonance imaging versus conventional angiography.

3.0-T magnetic resonance (MR) angiography and MR imaging were compared with conventional angiography for the evaluation of moyamoya disease in 13 preoperative patients (26 hemispheres) with moyamoya disease (4 males and 9 females aged 21-54 years). The correlation between MR angiography scores determined by modified Houkin's grading system (MRA score) and conventional angiography stages determined by Suzuki's grading system (CA stage) was analyzed. Other MR findings such as moyamoya vessel scores, "ivy sign" scores, and the presence of small, medium, and large cerebrovascular attack (CVA) lesions were compared with CA stages. MRA scores were significantly correlated with CA stages (p < 0.01). Moyamoya vessel scores correlated well with CA stages (p < 0.01). There was no significant correlation between "ivy sign" scores and CA stages, and no significant differences in CA stages with the presence and absence of CVA lesions of any size. 3.0-T MR angiography can be used as a vascular assessment in moyamoya disease with its priority of noninvasive nature and visual clarity compared with conventional angiography. The findings of 3.0-T MR angiography may reflect the steno-occlusive changes in moyamoya disease.

Arterial spin-labeling MR imaging in moyamoya disease compared with SPECT imaging.

OBJECTIVE: Arterial spin-labeling (ASL) is a noninvasive magnetic resonance (MR) imaging method used to obtain brain perfusion information on various cerebrovascular diseases. We retrospectively compared the use of ASL-MRI and single-photon emission CT (SPECT) imaging to determine absolute cerebral blood flow (CBF) in moyamoya disease. MATERIALS AND METHODS: CBF examinations using ASL-MRI on 3-T MRI and SPECT imagings with iodine-123-N-isopropyl-p-iodoamphetamine at resting (rest-IMP) and after acetazolamide challenge (ACZ-IMP) were performed on 12 patients with moyamoya disease (men, 5; women, 7; age range/average (year), 7-66/35.0). The CBF values determined by ASL-MRI (ASL-value), rest-IMP (rest-IMP-value), and ACZ-IMP (ACZ-IMP-value) of cerebral hemispheres (24 sides) were measured with normalized CBF maps created from data of those 3 perfusion imaging methods. Cerebrovascular reactivity (CVR) was calculated as follows: {(ACZ-IMP-value)-(rest-IMP-value)}/(rest-IMP-value)×100 (%). The ASL-value was compared with the rest-IMP-value, ACZ-IMP-value, and CVR. RESULTS: The ASL-value, rest-IMP-value, ACZ-IMP-value, and CVR (average±standard deviation) were 26.6±14.8 (mL/100 g/min), 27.5±6.4 (mL/100 g/min), 37.1±13.2 (mL/100 g/min), and 35.9±44.3 (%), respectively. Significant relationships between the ASL-value versus (vs.) the rest-IMP-value (rs=0.500, p<0.05), the ASL-value vs. the ACZ-IMP-value (rs=0.863, p<0.01), and the ASL-value vs. the CVR (rs=0.699, p<0.01) were observed. CONCLUSION: Although the ASL-value was lower than the rest-IMP-value, the significant relationship between the ASL-value and the rest-IMP-value may suggest that perfusion imaging by ASL-MRI could be used to recognize the condition of brain perfusion. In particular, the stronger correlation coefficient between the ASL-value and ACZ-IMP-value might suggest that perfusion imaging by ASL-MRI could show the potentially dangerous zone for ischemia.

Diffusion-weighted MR imaging in gynecologic cancers.

Diffusion-weighted imaging (DWI) reflects changes in proton mobility caused by pathological alterations of tissue cellularity, cellular membrane integrity, extracellular space perfusion, and fluid viscosity. Functional imaging is becoming increasingly important in the evaluation of cancer patients because of the limitations of morphologic imaging. DWI is being applied to the detection and characterization of tumors and the evaluation of treatment response in patients with cancer. The advantages of DWI include its cost-effectiveness and brevity of execution, its complete noninvasiveness, its lack of ionizing radiation, and the fact that it does not require injection of contrast material, thus enabling its use in patients with renal dysfunction. In this article, we describe the clinical application of DWI to gynecological disorders and its diagnostic efficacy therein.

Operative strategy for descending and thoracoabdominal aneurysm repair with preoperative demonstration of the Adamkiewicz artery.

BACKGROUND: Our study aimed to demonstrate the efficacy of preoperative intraarterial computed tomographic angiography to identify the Adamkiewicz artery (AKA). We also aimed to investigate the impact of identification of the AKA on the strategy for preventing spinal cord injury. METHODS: Thirty-seven patients (24 cases of descending aortic aneurysms and 13 cases of thoracoabdominal aortic aneurysms), were studied. Average age was 63.8 years old. A pigtail catheter was inserted into the descending aorta and its tip was located immediately below the left subclavian artery. Subsequently, intraarterial computed tomographic angiography was performed and the segmental artery to the AKA was identified. Aneurysms were replaced electively with prosthetic graft in all cases. In cases where the aortic segment that supplied the AKA was cross-clamped, the identified segmental artery-AKA was selectively perfused. In these cases, the segmental artery-AKA was reconstructed with an interposition graft. RESULTS: Intraarterial computed tomographic angiography successfully identified the segmental artery-AKA in all patients. The average number of AKA observed per patient was 1.3± 0.6 AKAs. Selective perfusion of preoperatively identified segmental artery-AKAs was performed in 11 cases. The average number of reconstructed segmental arteries was 0.5 in descending aortic aneurysms and 1.7 in thoracoabdominal aortic aneurysms. Although paraparesis occurred in two patients (5%), the remaining 35 patients did not suffer spinal cord injury. CONCLUSIONS: Intraarterial computed tomographic angiography reliably identifies the segmental-AKA. Furthermore, selective perfusion of the segmental artery-AKA, based on accurate preoperative identification, might be one option for preventing intraoperative spinal cord ischemia.

Magnetic resonance imaging of large chromophobe renal cell carcinomas.

PURPOSE: The objective of this study was to clarify the magnetic resonance imaging (MRI) findings of large chromophobe renal cell carcinomas. MATERIALS AND METHODS: Five patients diagnosed pathologically with chromophobe renal cell carcinoma are included. MRI findings were retrospectively evaluated for the tumor contour, uniformity and hypointensity of the rim of the tumor on T2-weighted images, "microscopic fat," enhancement degree and pattern on dynamic study, and necrosis in the tumor, among other findings. RESULTS: The tumor size ranged from 4.8 to 13.7 cm (mean 7.9 cm). The tumor contour was well defined in four patients. All but one tumor showed a hypointensity rim, and all tumors had a heterogeneous appearance on T2-weighted images. "Microscopic fat" was detected in one case. All tumors demonstrated low enhancement compared to that of the renal cortex. All tumors showed heterogeneous enhancement on postcontrast images. Necrosis was seen in four. Hemorrhage and renal vein thrombosis was seen in one. CONCLUSION: Chromophobe renal cell carcinomas of large size tend to have a heterogeneous appearance on postcontrast and T2-weighted images, a well-defined tumor contour with a hypointensity rim on T2-wighted images, and lower enhancement than that of the renal cortex. Tumor necrosis is easily apparent, and "microscopic fat" may be observed.