Magnetic Resonance Appearance Research Articles

CT and MR Appearance of Teeth: Analysis of Anatomy and Embryology and Implications for Disease.

Abnormalities of dental development and anatomy may suggest the presence of congenital or acquired anomalies. The detection of abnormalities, therefore, is an important skill for radiologists to achieve. Knowledge of dental embryology and an understanding of the radiologic appearances of teeth at various stages of maturation are required for the appreciation of abnormal dental development. While many tooth abnormalities are well-depicted on dedicated dental radiographs, the first encounter with a dental anomaly may be by a radiologist on a computed tomographic (CT) or magnetic resonance (MR) exam performed for other reasons. This article depicts normal dental anatomy and development, describing the appearance of the neonatal dentition on CT and MRI, the modalities most often encountered by clinical radiologists. The radiology and dental literature are reviewed, and key concepts are illustrated with supplemental cases from our institution. The value of knowledge of dental development is investigated using the analysis of consecutive MR brain examinations. Finally, the anatomical principles are applied to the diagnosis of odontogenic infection on CT. Through analysis of the literature and case data, the contrast of dental pathology with normal anatomy and development facilitates the detection and characterization of both congenital and acquired dental disease.

Phenotyping of giant cell myocarditis versus cardiac sarcoidosis using cardiovascular magnetic resonance

BackgroundGiant cell myocarditis (GCM) and cardiac sarcoidosis (CS) are rare inflammatory diseases of the myocardium with poor prognosis. Little is known about the cardiovascular magnetic resonance (CMR) appearance of GCM and the methods ability to distinguish the two rare entities from one another. MethodsWe assessed a total of 40 patients with endomyocardial biopsy-proven GCM (n = 14) and CS (n = 26) concerning their clinical and CMR appearance in a blinded manner. ResultsPatients with GCM and CS were of similar median age (55 vs 56 years), and a male predominance was observed in both groups. In GCM, median levels of troponin T (313 vs 31 ng/L, p < 0.001), and natriuretic peptides (6560 vs 676 pg/mL, p < 0.001) were higher than in CS, and the clinical outcome worse (p = 0.04). On CMR imaging, the observed alterations of left and right ventricular (LV/RV) dimensions and function were similar. GCM showed multifocal LV late gadolinium enhancement (LGE) with a similar longitudinal, circumferential, and radial distribution as in CS, including suggested signature imaging biomarkers of CS like the “hook sign” (71% vs 77%, p = 0.702). The median LV LGE enhanced volume was 17% and 22% in GCM and CS (p = 0.150), respectively. The number of RV segments with pathologically increased T2 signal and/or LGE were most extensive in GCM. ConclusionsThe CMR appearance of both GCM and CS is highly similar, making the differentiation between the two rare entities solely based on CMR challenging. This stands in contrast to the clinical appearance, which seems to be more severe in GCM.

Epithelial Myoepithelial Carcinoma Masquerading as Simple Parotid Cyst in a Middle Aged Male.

Epithelial-Myoepithelial Carcinoma (EMC) is a very rarely seen biphasic tumour typically seen in older females and constitutes 0.5-1% of all salivary gland neoplasms. The parotid gland is most often involved and occasionally there may be involvement of submandibular and minor salivary glands. Clinical picture often reveals benign nature of the disease. Computed tomography (CT) and magnetic resonance appearances are non-specific and the cytological diagnosis may be challenging, thus more accurate diagnosis can only be made by histological and immunohistochemical study. There is no consensus regarding the optimal treatment of this neoplasm, largely due to its rarity. Wide surgical excision with a clear margin is the treatment of choice because of the tumour's tendency to infiltrate locally. Adjuvant radiotherapy is often required in cases of large primary tumours and positive surgical margins. The tumour may commonly recur locally after resection in 30-50% of cases. We herein present an unusual case of a 46-year-old male who presented with cystic swelling of left parotid gland and diagnosed as EMC on histopathology and immunohistochemical examination. The patient was treated with surgical resection followed by post-operative radiotherapy.

Magnetic Resonance Appearance and Clinical Significance of Anterior Suprapatellar Fat Pad in Anterior Knee Pain

Introduction: Anterior knee pain (AKP) is a very common problem in the community and negatively affects the patient’s quality of life. Many pathologies can be the cause of this problem. The principal aim of our study was to evaluate the relationship between the magnetic resonance appearance of the suprapatellar fat pad and AKP. Methods: Knee magnetic resonance imaging of patients with and without AKP was analyzed retrospectively by two independent radiologists in two groups. The morphological structure of the anterior suprapatellar fat pad and other pathologies that may cause AKP in the knee joint were evaluated. Statistical relationships of the findings were investigated. Results: Of the 395 patients who participated in the study, 195 (49.4%) were females and 200 (50.6%) were males. The median age of the patients was 43 (18–90) years. There was no significant difference in mean age between individuals with and without AKP (p=0.376). A significant difference was found between patients with and without AKP in terms of posterior contour bowing of the anterior suprapatellar fat pad, edema, and diameter increase in the fat pad, patellar tendinopathy, quadriceps tendinopathy, and medial patellar retinaculum damage (p<0.001, p<0.001, p<0.001, p=0.015, p=0.002, and p=0.032, respectively). Discussion and Conclusion: Anterior suprapatellar fat pad syndrome is one of the pathologies involved in the etiology of AKP. The close relationship between the posterior contour bowing of the anterior suprapatellar fat pad we defined and AKP should be considered in radiological reporting.

EpCAM and microvascular obstruction in patients with STEMI: a cardiac magnetic resonance study

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This study was funded by “Instituto de Salud Carlos III” and “Fondos Europeos de Desarrollo Regional FEDER” Bachground. Microvascular obstruction (MVO) is negatively associated with cardiac structure and worse prognosis after ST-segment elevation myocardial infarction (STEMI). Epithelial cell adhesion molecule (EpCAM), involved in endothelium adhesion, is an understudied area in the MVO setting. Purpose. We aimed to evaluate whether EpCAM is associated with the appearance of cardiac magnetic resonance (CMR)-derived MVO and long-term systolic function in reperfused STEMI. Methods. We prospectively included 106 patients with a first STEMI treated with primary percutaneous coronary intervention, quantifying serum levels of EpCAM 24 hours post-reperfusion. All patients underwent CMR imaging 1 week and 6 months post-STEMI. The independent correlation of EpCAM with MVO, systolic volume indices, and left ventricular ejection fraction (LVEF) was evaluated. Results. The mean age of the sample was 59 ± 13 years and 76% were male. Patients were dichotomized according to EpCAM median (4.48 pg/mL). At 1-week CMR, lower EpCAM was related to extensive MVO (p-value = 0.02) and greater infarct size (p-value = 0.02). At presentation, only EpCAM values were significantly associated with the presence of MVO in univariate (Odds Ratio [95% confidence interval] (OR [95% CI]): 0.58 [0.38-0.88], p-value = 0.01) and multivariate logistic regression models (OR [95% CI]: 0.54 [0.34-0.85], p-value = 0.007). Although MVO tends to resolve at chronic phases, decreased EpCAM was associated with worse systolic function: depressed LVEF (p-value = 0.009) and higher left ventricular end-systolic volume (p-value = 0.04). Conclusions. EpCAM is associated with occurrence of CMR-derived MVO at acute phases and long-term adverse ventricular remodeling post-STEMI. Future studies are needed to confirm EpCAM as biomarker, and eventually biotarget in STEMI pathophysiology.

EpCAM y obstrucción microvascular en pacientes con un IAMCEST: estudio con resonancia magnética cardiaca

Introduction and objectivesMicrovascular obstruction (MVO) is negatively associated with cardiac structure and worse prognosis after ST-segment elevation myocardial infarction (STEMI). Epithelial cell adhesion molecule (EpCAM), involved in epithelium adhesion, is an understudied area in the MVO setting. We aimed to determine whether EpCAM is associated with the appearance of cardiac magnetic resonance (CMR)-derived MVO and long-term systolic function in reperfused STEMI. MethodsWe prospectively included 106 patients with a first STEMI treated with percutaneous coronary intervention, quantifying serum levels of EpCAM 24hours postreperfusion. All patients underwent CMR imaging 1 week and 6 months post-STEMI. The independent correlation of EpCAM with MVO, systolic volume indices, and left ventricular ejection fraction was evaluated. ResultsThe mean age of the sample was 59±13 years and 76% were male. Patients were dichotomized according to median EpCAM (4.48 pg/mL). At 1-week CMR, lower EpCAM was related to extensive MVO (P=.021) and larger infarct size (P=.019). At presentation, EpCAM values were significantly associated with the presence of MVO in univariate (OR, 0.58; 95%CI, 0.38-0.88; P=.011) and multivariate logistic regression models (OR, 0.55; 95%CI, 0.35-0.87; P=.010). Although MVO tends to resolve at chronic phases, decreased EpCAM was associated with worse systolic function: reduced left ventricular ejection fraction (P=.009) and higher left ventricular end-systolic volume (P=.043). ConclusionsEpCAM is associated with the occurrence of CMR-derived MVO at acute phases and long-term adverse ventricular remodeling post-STEMI.

EpCAM and microvascular obstruction in patients with STEMI: a cardiac magnetic resonance study

Introduction and objectivesMicrovascular obstruction (MVO) is negatively associated with cardiac structure and worse prognosis after ST-segment elevation myocardial infarction (STEMI). Epithelial cell adhesion molecule (EpCAM), involved in epithelium adhesion, is an understudied area in the MVO setting. We aimed to determine whether EpCAM is associated with the appearance of cardiac magnetic resonance (CMR)-derived MVO and long-term systolic function in reperfused STEMI. MethodsWe prospectively included 106 patients with a first STEMI treated with percutaneous coronary intervention, quantifying serum levels of EpCAM 24hours postreperfusion. All patients underwent CMR imaging 1 week and 6 months post-STEMI. The independent correlation of EpCAM with MVO, systolic volume indices, and left ventricular ejection fraction was evaluated. ResultsThe mean age of the sample was 59±13 years and 76% were male. Patients were dichotomized according to median EpCAM (4.48 pg/mL). At 1-week CMR, lower EpCAM was related to extensive MVO (P=.021) and larger infarct size (P=.019). At presentation, EpCAM values were significantly associated with the presence of MVO in univariate (OR, 0.58; 95%CI, 0.38-0.88; P=.011) and multivariate logistic regression models (OR, 0.55; 95%CI, 0.35-0.87; P=.010). Although MVO tends to resolve at chronic phases, decreased EpCAM was associated with worse systolic function: reduced left ventricular ejection fraction (P=.009) and higher left ventricular end-systolic volume (P=.043). ConclusionsEpCAM is associated with the occurrence of CMR-derived MVO at acute phases and long-term adverse ventricular remodeling post-STEMI.

Magnetic Resonance Characteristics of Baló Concentric Sclerosis in Children

BackgroundBaló concentric sclerosis is a rare demyelinating disease with characteristic magnetic resonance appearance of multilayered ringlike lesions of demyelination. This disease is extremely rare in children. We present the clinical data, radiological appearance, and development of lesions in eight children. MethodsWe analyzed the clinical information of eight patients diagnosed between 2012 and 2020. Magnetic resonance brain and spinal cord examinations with contrast medium administration were performed using a 1.5-T scanner. ResultsAll patients presented at least one typical Baló lesion on brain imaging. Four patients additionally had typical multiple sclerosis plaques. All primary Baló lesions had a characteristic appearance of concentric hyperintense rings on T2-weighted imaging and were round or ovoid. Cerebrospinal fluid analysis was performed in all patients. Oligoclonal bands were present in seven patients, and four of them had multiple sclerosis plaques on baseline brain magnetic resonance imaging. ConclusionBaló concentric sclerosis in children is characterized by acute and severe onset with hemiparesis as a predominant symptom. The size, contrast enhancement, and restricted diffusion depend on the phase of the disease.

MR Imaging–Pathologic Correlation of Uveal Melanomas Undergoing Secondary Enucleation after Proton Beam Radiotherapy

Background: Currently, radiotherapy represents the most widely employed therapeutic option in patients with uveal melanoma. Although the effects of proton beam radiotherapy on uveal melanoma end ocular tissues have been histologically documented, their appearance at MR imaging is still poorly understood. The purpose of our study was to elucidate the magnetic resonance (MR) semiotics of radiotherapy-induced changes to neoplastic tissues and ocular structures in patients with uveal melanoma undergoing secondary enucleation after proton beam radiotherapy. Methods: Nine patients with uveal melanoma who had undergone proton beam radiotherapy, MR imaging, and subsequent secondary enucleation were retrospectively selected. The histopathologic findings evaluated for irradiated tumors were necrosis, fibrosis, and viable tumor, while the histopathologic findings evaluated for extratumoral ocular/periocular tissues were radiation-related intraocular inflammation, vitreous hemorrhage, optic nerve degeneration, iris neovascularization, and periocular fibrotic adhesions. On MR images, the appearance of the abovementioned histologic features was assessed on conventional and diffusion-weighted sequences. Results: T2-weighted sequences performed better in detecting radiation-induced necrosis, fibrosis, optic nerve degeneration, and periocular fibrotic adhesions. T1-weighted sequences were preferable for identifying cataracts, vitreous hemorrhage, and inflammatory complications. Contrast-enhanced T1-weighted sequences were irreplaceable in assessing iris neovascularization, and in confirming inflammatory complications. Conclusions: In the light of their increasing role in the multidisciplinary management of patients with uveal melanoma, radiologists should be aware of the MR appearance of the effects of radiotherapy on neoplastic and ocular tissue, in order to improve the accuracy of follow-up MR examinations.

Magnetic Resonance Appearance of Pulmonary Type of Primary Small Cell Carcinoma of the Ovary: A Case Report and Literature Review

: The pulmonary type of primary small cell carcinoma of the ovary (SCCOPT) is a rare aggressive malignancy with a poor prognosis, usually occurring in postmenopausal women. Few literatures have emphasized on the magnetic resonance (MR) imaging features. In this paper, we analyze its MR imaging findings in combination with pathological manifestations. We report a case of a 51-year-old woman who presented with abdominal pain and distension. Several tumor markers were elevated. MR scan of the pelvis was performed. It revealed a heterogeneous lobulated mass with solid and cystic components originating from the right adnexa. The patient underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy. Histology showed a tumor comprising areas of classical small-cell carcinoma, and SCCOPT was diagnosed based on histopathology and immunohistochemistry. SCCOPT is a rare aggressive malignancy with certain characteristic imaging features. The solid component exhibits slightly higher signal on T2-weighted imaging with fat suppression, restricted diffusion on diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps, and honeycomb-like persistent enhancement. More data are needed to better understand its specific imaging manifestations.

Fully automated 3D segmentation of MR-imaged calf muscle compartments: Neighborhood relationship enhanced fully convolutional network

Automated segmentation of individual calf muscle compartments from 3D magnetic resonance (MR) images is essential for developing quantitative biomarkers for muscular disease progression and its prediction. Achieving clinically acceptable results is a challenging task due to large variations in muscle shape and MR appearance. In this paper, we present a novel fully convolutional network (FCN) that utilizes contextual information in a large neighborhood and embeds edge-aware constraints for individual calf muscle compartment segmentations. An encoder–decoder architecture is used to systematically enlarge convolution receptive field and preserve information at all resolutions. Edge positions derived from the FCN output muscle probability maps are explicitly regularized using kernel-based edge detection in an end-to-end optimization framework. Our method was evaluated on 40 T1-weighted MR images of 10 healthy and 30 diseased subjects by fourfold cross-validation. Mean DICE coefficients of 88.00–91.29% and mean absolute surface positioning errors of 1.04–1.66 mm were achieved for the five 3D muscle compartments.

Cortical formation abnormalities on foetal MR imaging: a proposed classification system trialled on 356 cases from Italian and UK centres

To formulate a classification system for foetal cortical formation abnormalities (CFAs) based on in utero magnetic resonance (iuMR) appearances and trial it in 356 cases. This retrospective study included all cases of foetal CFA diagnosed between 2000 and 2017 from seven centres in Italy and UK. All of the studies were reviewed by a panel of paediatric neuroradiologists experienced in iuMR with the aid of an algorithm designed to categorise the abnormalities. Consensus expert review confirmed 356 foetuses with CFA and the first level of classification distinguished bilateral CFA (229/356-64%) from unilateral CFA (127/356-36%) cases with sub-classification of the bilateral cases into asymmetric (65/356-18%) and symmetric (164/356-46%) involvement. There was a statistically significant excess of foetuses with small head size, e.g. 17% of the cohort had a bi-parietal diameter < 3rd centile. There was a small but statistically significant excess of males in the cohort. Further categorisation was made on fine anatomical structure. It is often not possible to classify foetal CFA using the principles and nomenclature used in paediatric neuroradiology. We have created a classification system for foetal CFA based on the analysis of 356 cases and believe that this will assist future research designed to correlate ante-natal and post-natal imaging features and understand the clinical sequelae of CFA described in utero. • We describe a morphological classification system of foetal brain cortical formation abnormalities that can be used in clinical practice. • This classification system can be used in future research studies to evaluate the long-term imaging and clinical outcomes of foetal brain cortical formation abnormalities in 17- to 38-week gestational age range. • The practical value of the work is in providing a framework and language to look for imaging clues that may differentiate between different CFA in further studies.

Diagnosis and Management of pituitary disease with focus on the role of Magnetic Resonance Imaging.

Magnetic resonance (MR) imaging is an essential tool in the diagnosis and management of pituitary diseases, indispensable for making correct treatment decisions. Successful management and follow-up of pituitary pathology requires an understanding of the MR appearance of normal and abnormal structures in the sellar region. This review will describe the MR appearance of the normal and abnormal pituitary gland and proposes an algorithm for the management strategy of some of the most common abnormalities in or around the sella.

Chronological low field magnetic resonance appearance of canine spinal epidural hemorrhage model.

The magnetic resonance (MR) features of spinal epidural hemorrhage depending with the passage of time have a meaning in veterinary medicine. The aim of this study is to propose the characteristic MR image of spinal epidural hemorrhage using a lower field permanent magnet scanner in dogs. A total of 8 clinically normal beagle dogs, weighing about 9 kg, were allocated. After a baseline MR examination, spinal epidural hemorrhage was created. MR scanning was executed on days 1, 2, 3, 4, 5, 10, 15, 20, 25, and 30 using 0.25 Tesla low field MR. Transverse MR images were attained for image examination. T2W, T1W, fluid-attenuated inversion recovery (FLAIR), short tau inversion recovery (STIR), and T2*-GRE sequences were used. Images were compared subjectively for signal transition assessment. Spinal epidural hemorrhage models were produced positively in 8 dogs at the T12 to L2 region. Initially, the spinal cord and epidural lesions were hyper-intense on T2W and T1W images. On T2W, FLAIR and STIR images, the spinal cord lesion was steadily hyperintense. No significant and consistent hypointense signal indicating hemorrhage was seen on T2*-GRE images. This study result suggests that relatively consistent hyperinstensity on T2 and FLAIR is observed for 30 days, meanwhile T2*-GRE imaging is less useful in hemorrhage detection.

Diffusion and perfusion MR patterns of central nervous system lymphomas.

Central nervous system lymphomas (CNSLs) are rare tumors which may show variable appearance in standard magnetic resonance imaging (MRI) depending on their origin (primary or secondary) or patients' immunological status. The aim of the study was to analyze imaging patterns of different CNSLs, using diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI). Our material consisted of 16 CNSLs (14 primary, 2 secondary, 13 immunocompetent, 3 immunodeficient) which underwent magnetic resonance (MR) examinations including DWI and T2* dynamic susceptibility contrast (DSC) perfusion (without a preload in 13 cases, with a preload in 3 subjects). In DWI, apparent diffusion coefficient (ADC), and in PWI, parameters of relative cerebral blood volume (rCBV), relative peak height (rPH) and relative percentage of signal recovery (rPSR) were analyzed within the entire tumor (mean values) and in regions with minimal diffusion (ADCmin) and maximal perfusion values (rCBVmax, rPHmax, rPSRmax). All CNSLs showed low values of ADCmean (0.70 × 10-3), ADCmin (0.54 × 10-3), rCBVmean (0.80), rCBVmax (1.27), rPHmean (1.05), rPHmax (1.59), as well as high values of rPSRmean (1.99) and rPSRmax (2.41). There were no significant differences in rCBVmax, as well as in all ADC, rPH and rPSR values between primary and secondary CNSLs or between tumors in immunocompetent and immunodeficient patients. Dynamic susceptibility contrast PWI with a preload resulted in significantly higher rCBV, rPH and lower rPSR values. Despite various MR appearances, both primary and secondary CNSLs in immunocompetent and immunodeficient patients show very typical patterns of restricted diffusion and hypoperfusion with signal intensity curves returning above the baseline. Dynamic susceptibility contrast perfusion without a preload is recommended.

Characteristics of the ablation lesions in cardiac magnetic resonance imaging after radiofrequency ablation of ventricular arrhythmias in relation to the procedural success

In human patients, studies about the cardiac magnetic resonance (CMR) appearance of the acute radiofrequency (RF) lesions in relation to the procedural outcomes after catheter ablation (CA) of ventricular arrhythmias (VA) are scarce. We aimed to investigate the RF lesions characteristics in relation to the procedural success. Patients referred for ablation of VA received CMR (1.5 T) using gadolinium contrast before and after ablation. CA in left ventricle was performed using a 3.5-mm irrigated catheter. The volume and transmurality of the RF-induced lesions were measured in early gadolinium-enhanced postablation CMRs. Acute failure was defined as persistently inducible VA at the end of the CA. Twenty-five patients (60.7 ± 9.8 years, 19 with sustained ventricular tachycardia) were studied. All RF lesions had nonenhanced core. The volume of the nonenhanced lesions showed positive correlation with the maximal RF power (r = 0.598, P = .002) and the impedance drop (r = 0.416, P = .038). Patients with transmural (≥75%) lesions had significantly larger impedance drop as compared to those with nontransmural lesions (<75%): 20.3 ± 9.4 versus 13.5 ± 4.3, P = .037. In the failures, the lesions volume was nonsignificantly larger: 3.86 ± 3.3% versus 2.6 ± 1.7%, P = .197; however, it was considerably deeper: 86 ± 13% versus 62 ± 26%, P = .03. CMR after VA ablation showed nonenhanced lesions resembling the no-reflow phenomenon in myocardial infarction. Although the size and the depth of the RF injury correlated with the ablation energy and impedance drop, they were not associated with acute ablation success.

Normal magnetic resonance appearances of the temporomandibular joints in children and young adults aged 2-18years.

Knowledge of normal appearances of the temporomandibular joint (TMJ) is paramount when assessing the joint for disease in juvenile idiopathic arthritis. Reliable features defining normal TMJs in children are limited. To establish reliable normal standards for the TMJ at magnetic resonance imaging (MRI). We included children and young adults aged 2-18years undergoing a head MRI for reasons not believed to affect the TMJs. We assessed TMJ anatomy and contrast enhancement using a high-resolution 3-D T1-weighted sequence. We noted joint fluid and bone marrow oedema based on a T2-weighted sequence. Three experienced radiologists read all examinations twice in consensus and defined intraobserver consensus agreement. We evaluated the TMJs in 101 children and young adults (45 female), mean age 10.7years (range 2-18years). The intraobserver consensus agreement for the assessment of anterior condylar inclination in the sagittal/oblique plane was moderate to good (Cohen κ=0.7 for the right side). Cohen κ for intraobserver consensus agreement for condylar shape in the coronal plane on a 0-2 scale was 0.4 for the right and 0.6 for the left. Intraobserver agreement for measurement of joint space height and assessment of bone marrow oedema was poor. There was a statistically significant increase in anterior inclination by age in the sagittal plane on a 0-2 scale (P<0.0001). Eighty percent of the condyles showed a rounded shape in the coronal plane while 20% showed mild flattening. Thirty-five of 36 right TMJs showed contrast enhancement (mild enhancement in 32 joints, moderate in 3 joints). Subjective assessment of the anterior condylar inclination in the sagittal/oblique plane and condylar flattening in the coronal plane can be considered precise features for describing TMJ anatomy in healthy children. There is an increasing anterior inclination by age. Mild contrast enhancement of the TMJs should be considered a normal finding.

Subscapular Bursa: Anatomy and Magnetic Resonance Appearance.

Subscapular Bursa: Anatomy and Magnetic Resonance Appearance.

MR Imaging of Perianal Crohn Disease.

Pelvic magnetic resonance (MR) imaging is currently the standard for imaging perianal Crohn disease. Perianal fistulas are a leading cause of patient morbidity because closure often requires multimodality treatments over a prolonged period of time. This review summarizes clinically relevant anal sphincter anatomy, imaging methods, classification systems, and treatment objectives. In addition, the MR appearance of healing perianal fistulas and fistula complications is described. Difficult imaging tasks including the assessment of rectovaginal fistulas and ileoanal anastomoses are highlighted, along with illustrative cases. Emerging innovative treatments for perianal Crohn disease are now available and have the promise to better control sepsis and maintain fecal continence. Different treatment modalities are selected based on fistula anatomy, patient factors, and management goals (closure versus sepsis control). Radiologists can help maximize patient care by being familiar with MR imaging features of perianal Crohn disease and knowledgeable about what features may influence therapy decisions. © RSNA, 2017 Online supplemental material is available for this article.

MR appearance of normal uterine endometrium considering menstrual cycle: differentiation with benign and malignant endometrial lesions.

Background The thickness and signal intensity (SI) of normal uterine endometrium on T2-weighted (T2W) imaging changes depend on the menstrual cycle phase. Cases of normal endometrium that appear similar to endometrial lesions sometimes occur, and may result in misdiagnosis. Purpose To investigate normal endometrial appearance in luteal phase (LP) compared to that in follicular phase (FP), and to differentiate these appearances with those of endometrial lesions. Material and Methods Thirty-two normal volunteers prospectively underwent magnetic resonance (MR) examinations during LP and FP. Patients with pathologically confirmed endometrial polyps ( n = 9), hyperplasia ( n = 7), and cancer ( n = 15), who underwent MR examinations, were evaluated for comparison. Endometrial appearance was categorized into the following five types on sagittal T2W imaging and compared between LP, FP, and endometrial lesions: type 1, homogeneous higher SI; type 2, homogeneous iso SI; type 3, a bright midline and a peripheral iso SI layer; type 4, a lower/iso SI central line; and type 5, heterogeneous lower/iso SI. Endometrial thickness and SI were measured and also compared. Results Endometrial lesions were more frequently categorized as type 5 than normal endometrium ( P < 0.05). Endometrial thickness in LP (mean, 1.0 cm) was significantly greater than that in FP (0.6 cm), but not significantly different from polyps (1.1 cm), hyperplasia (1.0 cm), and cancer (0.9 cm). SI in FP was significantly higher than that in LP and that of all endometrial lesions. Conclusion Differentiation between normal endometrium in LP and endometrial lesions may be difficult based on thickness alone. Heterogeneous low SI may help to differentiate normal endometrium from endometrial lesions. Performing MR imaging during FP may also help due to higher SI of normal endometrium.