Fat-saturated Images Research Articles

T2 Relaxation Time and Apparent Diffusion Coefficient for Noninvasive Assessment of Renal Pathology After Acute Kidney Injury in Mice

Renal ischemia reperfusion injury leads to acute kidney injury (AKI) and is associated with tissue edema, inflammatory cell infiltration, and subsequent development of interstitial renal fibrosis and tubular atrophy. The purpose of this study was to investigate the value of the functional magnetic resonance imaging (MRI) techniques, T2 mapping, and diffusion-weighted imaging (DWI) in characterizing acute and chronic pathology after unilateral AKI in mice. Moderate or severe AKIs were induced in C57Bl/6 mice through transient unilateral clamping of the renal pedicle for 35 minutes (moderate AKI) or 45 minutes (severe AKI), respectively. Magnetic resonance imaging was performed in 10 animals with moderate AKI and 7 animals with severe AKI before surgery and at 5 time points thereafter (days 1, 7, 14, 21, 28) using a 7-T magnet. Fat-saturated T2-weighted images, multiecho turbo spin echo, and diffusion-weighed sequences (7 b values) were acquired in matching coronal planes. Parameter maps of T2 relaxation time and apparent diffusion coefficient (ADC) were calculated, and mean values were determined for the renal cortex, the outer medulla, and the inner medulla. Inflammatory cell infiltration with monocytes/macrophages (F4/80), T-lymphocytes (CD4, CD8), and dendritic cells (CD11c) as well as the degree of interstitial fibrosis 4 weeks after AKI were determined through renal histology and immunohistochemistry. Statistical analysis comprised unpaired t tests for group comparisons and correlation analysis between MRI parameters and kidney volume loss. Increase of T2 relaxation time, indicating tissue edema, was most pronounced in the outer medulla and reached maximum values at d7 after AKI. At this time point, T2 values in the outer medulla were significantly increased to 53.8 ± 2.5 milliseconds after the severe AKI and to 46.3 ± 2.3 milliseconds after the moderate AKI when compared with the respective contralateral normal kidneys (40.9 ± 0.9 and 36.4 ± 1.2 milliseconds, respectively; P < 0.01). The T2 values reached baseline by d28. Medullary ADC was significantly reduced at all time points after AKI; restriction of diffusion was significantly more pronounced after the severe AKI than after the moderate AKI at d14 and d28. Changes of renal T2 and ADC values were associated with the severity of AKI as well as the degree of inflammatory cell infiltration and interstitial renal fibrosis 4 weeks after AKI. Furthermore, relative changes of both MRI parameters significantly correlated with kidney volume loss 4 weeks after AKI. Measuring T2 and ADC values through MRI is a noninvasive way to determine the presence and severity of acute and chronic renal changes after AKI in mice. Thus, the method should prove useful in animal and human clinical studies.

Objective measurement of minimal fat in normal skeletal muscles of healthy children using T2 relaxation time mapping (T2 maps) and MR spectroscopy

Various skeletal muscle diseases result in fatty infiltration, making it important to develop noninvasive biomarkers to objectively measure muscular fat. We compared T2 relaxation time mapping (T2 maps) and magnetic resonance spectroscopy (MRS) with physical characteristics previously correlated with intramuscular fat to validate T2 maps and MRS as objective measures of skeletal muscle fat. We evaluated gluteus maximus muscles in 30 healthy boys (ages 5-19years) at 3T with T1-weighted images, T2-W images with fat saturation, T2 maps with and without fat saturation, and MR spectroscopy. We calculated body surface area (BSA), body mass index (BMI) and BMI percentile (BMI %). We performed fat and inflammation grading on T1-W imaging and fat-saturated T2-W imaging, respectively. Mean T2 values from T2 maps with fat saturation were subtracted from T2 maps without fat saturation to determine T2 fat values. We obtained lipid-to-water ratios by MR spectroscopy. Pearson correlation was used to assess relationships between BSA, BMI, BMI %, T2 fat values, and lipid-to-water ratios for each boy. Twenty-four boys completed all exams; 21 showed minimal and 3 showed no fatty infiltration. None showed muscle inflammation. There was correlation between BSA, BMI, and BMI %, and T2 fat values (P < 0.05), and between BMI and BMI %, and lipid-to-water ratios (P < 0.05). There was strong correlation between T2 fat values and lipid-to-water ratios (P < 0.0001, r = 0.83). T2 maps and MR spectroscopy correlate with physical characteristics associated with fatty infiltration of skeletal muscles, even in microscopic amounts, and validate each other. Both techniques might enable detection of minimal pathological fatty infiltration in children with skeletal muscle disorders.

Dissection of internal carotid and vertebral arteries: clinical presentation, diagnosis, and treatment

The paper gives the data available in the literature and the author’s results of an examination of almost 140 patients with dissection of the internal carotid and vertebral arteries (ICA and VA). Dissection is blood penetration through an intimal tear from the lumen of an artery into its wall to develop intramural hematoma (IMH). The cause of dissection is the weakness of the arterial wall presumably due to mitochondrial cytopathy. IMH narrows/occludes the arterial lumen or is a source of arterioarterial embolism, which in turn leads to ischemic stroke. Stroke as a result of dissection generally develops in young patients, who are not prone to traditional vascular risk factors, frequently after the influence of provocative factors (mild head/neck injury, head jerks, physical strain, contraceptives, etc.). The characteristics of stroke are head/neck pain on the side of dissection that appears a few days prior to stroke or simultaneously with the latter; quite often a good recovery of impaired functions; and low recurrence rates. Another major manifestation, isolated cervicocephalic pain, is encountered in PA dissection more frequently (in almost a third of cases) and in ICA dissection less frequently (about 5%). Magnetic resonance (MR) angiography and fat-saturated T1-weighted MR imaging play a leading role in the verification of dissection. Dissection should be treated with anticoagulants/antiaggregants in its acute phase, as well as with trophic drugs, primarily actovegin, in both acute and chronic phases.

MR diffusion tensor imaging of normal kidneys.

To assess the feasibility of diffusion tensor imaging (DTI) of normal kidneys and the influence of hydration state. Ten healthy volunteers underwent renal DTI after fasting for 12 hours and 4 hours, without fasting, and following water diuresis. Medullary and cortical apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured and compared in the four different states of hydration. DTI was performed with a 3T magnetic resonance imaging (MRI) system using fat-saturated single-shot spin-echo echo planar imaging sequence. ADC of normal cortex (2.387 ± 0.081 × 10(-3) mm(2) /s) was significantly higher (t = 20.126, P = 0) than that of medulla (1.990 ± 0.063 × 10(-3) mm(2) /s). The FA value of normal cortex (0.282 ± 0.017) was significantly lower (t = -42.713, P = 0) than that of medulla (0.447 ± 0.022). The ADC and FA values of the left renal cortex (2.404 ± 0.082 × 10(-3) mm(2) /s, 0.282 ± 0.017) and medulla (2.002 ± 0.081 × 10(-3) mm(2) /s, 0.452 ± 0.024) were not significantly different (P > 0.05) from those of right renal cortex (2.369 ± 0.080 × 10(-3) mm(2) /s, 0.283 ± 0.018) and medulla (1.978 ± 0.039 × 10(-3) mm(2) /s, 0.443 ± 0.019). Values for ADC (×10(-3) mm(2) /s) and FA in the 12-hour fasting, 4-hour fasting, nonfasting, and water diuresis states were 2.372 ± 0.095 and 0.278 ± 0.018, 2.387 ± 0.081 and 0.282 ± 0.017, 2.416 ± 0.051 and 0.279 ± 0.023, 2.421 ± 0.068, and 0.270 ± 0.021, respectively, in cortex, 1.972 ± 0.084 and 0.438 ± 0.014, 1.990 ± 0.063 and 0.447 ± 0.022, 2.021 ± 0.081 and 0.450 ± 0.031, 2.016 ± 0.076 and 0.449 ± 0.028, respectively, in medulla. The ADC and FA values in different hydration states were not significantly different (P > 0.05). DTI of normal kidneys is feasible with reproducible ADC and FA values independent of hydration states.

Parenchymal Anaplastic Astrocytoma Presenting With Visual Symptoms Due to Bilateral Optic Nerve Sheath Involvement

A 23 year old man presented with transient visual obscurations and was found to have optic nerve edema and a thalamic lesion that did not enhance on magnetic resonance imaging. Lumbar puncture opening pressure was normal. Subsequent magnetic resonance images demonstrated optic nerve sheath enhancement. Pathological diagnosis of the thalamic mass was anaplastic astrocytoma (WHO grade III). Visual symptoms were attributed to spread of high grade parenchymal glioma to the optic nerve sheaths causing intraorbital optic nerve compression.

Normal intracranial periarterial enhancement on pediatric brain MR imaging

Large/medium vessel vasculitis is an important etiology of childhood stroke. Early research suggests vessel wall enhancement on postcontrast MRI may be a marker of intracranial vasculitis yet no systematic descriptions of normal periarterial enhancement exist in the literature. The aim was to describe normal periarterial enhancement in the pediatric population. We included all children who had an MR scan between January 2007 and December 2010, with normal parenchymal imaging, no clinical concern of vasculopathy, and axial and coronal postcontrast fat-saturated T1-weighted images with 3-mm slice thickness. Intensity of periarterial enhancement was graded on a three-point scale by two investigators for all intracranial large and medium arteries. A total of 44 patients aged 4 months to 16 years were included. Inter- and intra-rater reliability in enhancement grading was high (all kappa >0.65). Thin, linear, noncircumferential periarterial enhancement was common and usually symmetrical. It was most commonly prominent in the cavernous and petrous segments of the internal carotid artery and the M1 segment of the middle cerebral artery. Periarterial enhancement was rarely observed at segments surrounded by CSF, including supraclinoid segments of the internal carotid arteries, P1 segments of the posterior cerebral arteries, V4 segments of the vertebral artery, and the basilar arteries. Normal periarterial enhancement is common and usually symmetrical along major intracranial arteries but rarely seen around arterial segments bordered by CSF. Knowledge of these findings may be useful for a sensitive and specific interpretation of MR scans of patients with clinical concerns of vasculitis.

THU0463 Protracted Febrile Myalgia of Familial Mediterranean Fever can be Reliably Detected by Magnetic Resonance Imaging: A Comprehensive Analysis of 20 Cases

BackgroundProtracted febrile myalgia (PFM) is a rare and least well recognized manifestation of familial Mediterranen fever (FMF), characterized by prolonged excruciating muscle pain, tenderness, fever, and elevated levels of acute...

Parotid Fat Contents in Healthy Subjects Evaluated with Iterative Decomposition with Echo Asymmetry and Least Squares Fat-Water Separation

To evaluate the effectiveness of three fat measurement methods for parotid glands in healthy subjects, with or without metallic dental implants. The institutional review board approved this study, with informed consent obtained from 114 volunteers undergoing magnetic resonance (MR) imaging at 1.5 T. Fat-saturated (FS) and non-fat-saturated (NFS) fast spin-echo T1-weighted imaging (T1 method), FS and NFS T2-weighted periodically rotated overlapping parallel lines with enhanced reconstruction fast spin-echo imaging (T2 method), and gradient-echo imaging with fat-water separation using iterative decomposition with echo asymmetry and least squares (IDEAL) method were used to derive parotid fat contents. Two raters examined the homogeneity of fat saturation to determine whether parotid fat quantification was successful, with the success rate in the 114 subjects recorded for each protocol. In subjects whose fat quantification was successful with all three imaging methods, linear regression was used to analyze the correlation between any pair of the three parotid fat content measurement methods. Success rates in parotid fat measurements by using T1, T2, and IDEAL methods were 87.7% (100 of 114), 87.7% (100 of 114), and 100% (114 of 114), respectively. The means of measured parotid fat contents revealed significant differences (P < .001) between any pair of the three measurement methods. The parotid fat contents measured with the three methods were significantly correlated with each other between any pair of combinations. The IDEAL method provided a high success rate for parotid fat measurements, even in subjects with metallic dental implants.

SU-D-WAB-02: MRI-Based Treatment Planning in Brain Radiation Therapy: Validation of An Atlas-Based Pseudo-CT Generation Method

Purpose: To quantify the dosimetric accuracy of an atlas‐based pseudo‐CT (p‐CT) generation method in MRI‐based treatment planning, and to evaluate the influence of specific MRI sequences on p‐CT quality. Methods: For six brain IMRT patients, a p‐CT was generated from an MR image set previously used for target delineation. A research version of Advantage SIM™ software (GE Healthcare) was used to produce the p‐CT. The software uses body segmentation and bone enhancement on the input MRI, to produce a p‐CT image with a contrast similar to that of a bone atlas generated offline. The IMRT plan including the isocenter was copied on to the p‐CT and the dose was calculated in Pinnacle™. The two dose distributions were compared using (1) gamma analysis, and (2) differences between the average DVH for the target volume, and tissue contour. Results: The p‐CT visually co‐registered well with both the MRI and conventional CT in four cases where Axial T1 Spin Echo or Fast Spoiled Gradient‐Recalled Echo images were used. For these cases, the average Gamma Index 3%/3mm pass rates were 96.85%, 95.58% and 95.40%, in the axial, coronal and sagittal planes. On average, the absolute value difference between the average DVHs was 1.74 (max: 6.97) and 0.95 (max: 16.7) percentage points, for the tissue contour and target volume, respectively. Two of the MR image sequences (Axial T2 Flair and Axial T1 Fat Sat images) resulted in poor quality p‐CTs and were not used for dose comparison. Conclusion: A good agreement was seen between the p‐CT and CT dose distributions in this preliminary study, showing the potential for using MRI for both target delineation and dose calculation for brain treatments, with the clinical integration of an automated p‐CT generation method, and appropriate MRI sequences.

The carpometacarpal joint of the thumb: MR appearance in asymptomatic volunteers

To prospectively characterize the MR appearance of the carpometacarpal (CMC) joint of the thumb in asymptomatic volunteers. Thirty-four asymptomatic volunteers (17 women, 17 men, mean age, 33.9 ± 9.2years) underwent MR imaging of the thumb after approval by the local ethical committee. Two musculoskeletal radiologists independently classified visibility and signal intensity (SI) characteristics of the anterior oblique (AOL/beak ligament), the posterior oblique (POL), the intermetacarpal (IML), and the dorsoradial ligaments (DRL) on a three-point Likert scale. The thickness of all ligaments, cartilage integrity, and presence of joint fluid were assessed. The alignment of the first metacarpal base with the trapezium was quantified on sagittal and coronal planes. The ligaments of the CMC joint were constantly visible in all volunteers for the POL and IML, and in all but one for the AOL and DRL. On intermediate-weighted fat-saturated images the POL (65%/74% reader 1/reader 2) and DRL (58%/64%) were commonly of increased SI, while the IML had a striated appearance in 91%/76% of subjects. The AOL showed a variable SI (36%/42% low, 27%/27% increased, 36%/30% striated). The IML was the thickest ligament with a mean of 2.9mm/3.1mm and the DRL the thinnest (1.2mm/1.4mm). There was a mean dorsal subluxation of 1.8mm/2.0mm and radial subluxation of 2.8mm/3.4mm of the metacarpal base. The AOL was significantly thicker in men (1.7mm) than in women (1.2mm; p = 0.02). Radial subluxation was significantly larger in men (3.4mm) than in women (2.2mm; p = 0.02). No subluxation in palmar or ulnar direction was seen. Radial and dorsal subluxation of the CMC joint can be a normal finding in a resting position at MR imaging. The CMC ligaments showed a considerable variability of signal intensity with a typically striated IML; thickness of the AOL is typically less than 2.2mm, of the POL typically less than 2.9mm.

Parotid perfusion in nasopharyngeal carcinoma patients in early-to-intermediate stage after low-dose intensity-modulated radiotherapy: Evaluated by fat-saturated dynamic contrast-enhanced magnetic resonance imaging

PurposeTo investigate parotid perfusion in early-to-intermediate stage after parotid-sparing radiation dose using fat-saturated DCE-MRI, and to verify whether the perfusion alteration was related to radiation dose and the PSV. Methods and MaterialsThirty-two parotid glands from 16 consecutive patients with pathologically proven nasopharyngeal carcinoma treated by IMRT were examined. The parotid glands received a radiation dose of 28.9±3.9Gy with a PSV of 43.1%±13.9%. Perfusion parameters were calculated using time-shifted Brix model from fat-saturated DCE-MRI data before (pre-RT) and in early-to-intermediate stage after (post-RT) IMRT. Paired t-test was used to evaluate perfusion changes, while Pearson's correlation test was used to examine perfusion dependency on radiation dose and PSV. For multiple comparisons Bonferroni correction was applied. ResultsSuccessful fat saturation was achieved in 29 of 32 parotid glands. Compared with pre-RT, the post-RT parotid glands showed significantly higher A, peak enhancement, and wash-in slope, plus a lower Kel, suggesting a mixed effect of increased vascular permeability and acinar loss. Linear regression showed that peak enhancement was positively associated with radiation dose in post-RT parotid glands. Kel and slope were negatively associated with PSV, while time-to-peak was positively associated with PSV significantly. ConclusionsOur results suggest that time-shifted Brix model is feasible for quantifying parotid perfusion using DCE-MRI. The perfusion alterations in early-to-intermediate stage after IMRT might be related to a mixed effect of increased vascular permeability and acinar loss with dose and PSV dependencies.

Current MR Imaging Lipid Detection Techniques for Diagnosis of Lesions in the Abdomen and Pelvis

One application of the unique capability of magnetic resonance (MR) imaging for characterizing soft tissues is in the specific detection of lipid. Adipose tissue may be abundant in the body, but its presence in a lesion can greatly limit differential diagnostic considerations. This article reviews MR imaging fat detection techniques and discusses lesions in the abdomen and pelvis that can be readily diagnosed by using these techniques. Traditional fat detection methods include inversion-recovery and chemically selective fat-suppression pulse sequences, with the former being less sensitive to field heterogeneity and less tissue specific than the latter. Chemical shift-based sequences, which exploit the inherent resonance frequency difference between lipid and water to depict intracytoplasmic fat, have great utility for evaluating hepatic steatosis and lesions such as adrenal and hepatic adenomas, hepatocellular carcinoma, focal lipomatosis of the pancreas, and adrenal cortical carcinoma. The signal from large amounts of fat can be suppressed by using a narrow radiofrequency pulse for selective excitation of fat protons (ie, fat saturation imaging), a technique that increases image contrast resolution and highlights lesions such as contrast-enhancing tissue, edema, and blood products. This technique is especially useful for evaluating renal angiomyolipomas, adrenal myelolipomas, ovarian teratomas, and liposarcomas. MR spectroscopy is a promising method for quantifying absolute liver fat concentration and changes in hepatic triglyceride content during treatment. New and evolving techniques include magnetization transfer and modified Dixon sequences. A solid understanding of these techniques will help improve the interpretation of abdominal and pelvic imaging studies.

Propranolol as a First‐line Treatment for Diffuse Infantile Hepatic Hemangioendothelioma

Propranolol as a First‐line Treatment for Diffuse Infantile Hepatic Hemangioendothelioma

MRI assessment of tenosynovitis in children with juvenile idiopathic arthritis: inter- and intra-observer variability

There is sparse knowledge about grading tenosynovitis using MRI. The purpose of this study was to assess the reliability of a tenosynovitis MRI scoring system in juvenile idiopathic arthritis. Children with juvenile idiopathic arthritis and wrist involvement were enrolled in two paediatric centres, from October 2006 to January 2010. The extensor (compartments II, IV and VI) and flexor tendons were assessed for the presence of tenosynovitis on T1-weighted postcontrast fat-saturated MR images and were scored from 0 (normal) to 2 (moderate to severe) by two observers independently. Intra- and interobserver agreement was assessed. Ninety children (age range: 5-18.5 years) were included, of whom 34 had tenosynovitis involving extensors and 28 had tenosynovitis involving flexors. A total of 360 tendon areas were analysed, of which 114 had tenosynovitis (86/270 extensors and 28/90 flexors). Intra-reader 1 agreement was excellent for the extensors (k = 0.82-0.91) and for the flexors (k = 0.85); intra-reader 2 agreement was moderate to good for the extensors (k = 0.51-0.72) and good for the flexors (k = 0.64). Inter-reader agreement was good for the extensors (k = 0.69-0.73) and moderate for the flexors (k = 0.49). The proposed MRI scoring system for the assessment of wrist tenosynovitis in juvenile idiopathic arthritis appears feasible with an observer agreement sufficient for clinical use.

Erratum

Radiology: Volume 266: Number 1—January 2013 n radiology.rsna.org 367 poor with the in-phase 2D T1-weighted images. Retrospectively going through our analysis, we found that we would have missed cast in one of the cases with use of 2D opposed-phase imaging instead of 3D fat-saturated imaging and vice versa in another case. In our experience, artifacts owing to high inflow have not hampered the diagnostic accuracy of the 2D images. In conclusion, we therefore suggest performing both sequences and using both for the detection of biliary cast.

Bone marrow lesions in knee osteoarthritis change in 6–12 weeks

SummaryObjectivesKnee osteoarthritis (OA) is thought to be a slowly evolving disease with glacial changes in cartilage morphology necessitating trials of potential treatments lasting 1–2 years with evidence that over 6 months change in cartilage is not detectable. In contrast to cartilage, bone has the capacity to adapt rapidly, such as after fracture. We tested whether bone marrow lesions (BMLs) change in volume in 6 and 12 weeks, suggesting they may provide evidence of short term fluctuations of joint damage.MethodsIn 62 patients with patellofemoral knee OA (mean age 55.7 years, 59.7% women, mean BMI 31.0), we obtained baseline, 6 and 12 week knee MRIs with contrast enhancement. Of those with BMLs at baseline, we assessed BML volume on the axial proton density fat saturated (FS) images and postcontrast sagittal T1 weighted FS images. We manually segmented BML volumes, testing repeatability of BML volumes in knees remeasured. Using the standard deviation of the difference between repeated measurements to calculate Bland–Altman Limits of Agreement, we determined how much BML volume change represented a change greater than due to chance.ResultsFifty-two patients had BMLs at baseline. Test–retest reliability for BML volume was high (ICC 0.89, 95% CI 0.80–0.97). All knees showed at least some change in BML volume by 6 and 12 weeks. On the axial view at 6 weeks, 20/49 (40.8%) knees showed BML volume changes greater than the limits of agreement with similar results at 12 weeks. BML changes were evenly divided among knees with enlarging and shrinking BMLs. 63.3% of the knees had more than 50% change in BML volume at either 6 or 12 weeks on the axial view and 48.7% on the sagittal view.ConclusionsKnee BML volumes change in several weeks in many persons with knee OA. To the extent that they could be regarded as treatment targets, trials testing BML effects could avoid the usual prolonged structure modification trials.

ECG-Gated Multiecho Dixon Fat-Water Separation in Cardiac MRI: Advantages Over Conventional Fat-Saturated Imaging

The purpose of this pictorial essay is to explore the advantages of multiecho Dixon fat-water separation techniques in cardiac MRI. The clinical indications, potential artifacts, and imaging findings with this technique are reviewed. Multiecho Dixon fat-water separation can be used to help characterize cardiac masses, evaluate for myocardial lipomatous infiltration, and diagnose pericarditis. Advantages over conventional fat-saturation techniques include fewer artifacts from background inhomogeneity, improved contrast of microscopic fat, and capability for use in combination with cine and contrast-enhanced imaging.

Comparison of inversion recovery and contrast-enhanced T1-weighted fat-suppressed sequences for the staging of cervical lymphoma

In a retrospective analysis with two readers blinded to the clinical information, coronal short tau inversion recovery (STIR) images were compared to contrast-enhanced fat-saturated T1-weighted imaging (T1 CEfs) in 51 cases of cervical lymphoma.Interrater reliability was good to excellent.Although sensitivity and subjective quality of the STIR sequence were higher than those of the T1 CEfs sequence (sensitivity 85%/72%, respectively), specificity (82%/95%) as well as positive likelihood ratio (4.65/15.93) was much lower. Therefore, contrast-enhanced sequences should be included in the primary staging of lymphoma.

Paget's Disease of the Calcaneus Causing Right Foot Pain

"Paget's Disease of the Calcaneus Causing Right Foot Pain." Baylor University Medical Center Proceedings, 25(2), pp. 161–162

Multiple Penile Schwannomas and Their Magnetic Resonance Imaging Characteristics

Penile schwannoma is a rare encapsulated nerve sheath tumor of the peripheral nerve in the penis. Here, we report a case of multiple, painful, beadlike, nodular tumors in the penis of a 40-year-old man. The nodules showed well-defined margins and hypoechoic areas on gray-scale ultrasonograms. They showed high signal intensity on fat-saturated T2-weighted magnetic resonance imaging (MRI) and intense enhancement on gadolinium-enhanced T1-weighted MRI, compatible with their myxoid content. The nodules pressed against the tunica albuginea and some caused inward indentation, which we considered as indirect evidence of the tumor location. In conclusion, the MRI characteristics and location of the nodules together enable presurgical diagnosis of penile schwannomas, which is especially useful in asymptomatic patients and those unwilling to undergo surgery.