Gualdi Gf

MR Imaging of the Small Bowel

Small-bowel radiology has undergone dramatic changes in the past 2 decades. Despite important recent advances in small-bowel endoscopy, radiologic imaging remains important for patients suspected of having or with established small-bowel disease. Cross-sectional imaging techniques (computed tomography and magnetic resonance [MR] imaging), used to investigate both extraluminal abnormalities and intraluminal changes, have gradually replaced barium contrast examinations, which are, however, still used to examine early mucosal disease. MR imaging techniques clearly highlight endoluminal, mural and extramural enteric details and provide vascular and functional information, thereby enhancing the diagnostic value of these techniques in small-bowel diseases. Two MR imaging based techniques are currently utilized: MR enteroclysis and MR enterography. In enteroclysis, enteric contrast material is administered through a nasoenteric tube, whereas in enterography, large volumes of enteric contrast material are administered orally. MR enteroclysis ensures consistently better luminal distention than does MR enterography in both the jejunum and the ileum and more accurately depicts endoluminal abnormalities and early disease, particularly at the level of the jejunal loops. Moreover, MR enteroclysis provides a high level of accuracy in the diagnosis and exclusion of small-bowel inflammatory and neoplastic diseases and can be used for the first radiologic evaluation, while MR enterography may effectively be used to follow up both Crohn disease patients without jejunal disease and in pediatric patients where nasogastric intubation might be a problem. MR enteroclysis may also reveal subtle transition points or an obstruction in the lower small bowel, which may escape detection when more routine methods, including enterography, are used. MR imaging offers detailed morphologic information and functional data of small-bowel diseases and provides reliable evidence of normalcy, thereby allowing the diagnosis of early or subtle structural abnormalities and guiding treatment and decisions in patient care.

Small-Bowel Neoplasms: Prospective Evaluation of MR Enteroclysis

PURPOSE To prospectively evaluate the accuracy of magnetic resonance (MR) enteroclysis in the detection of small-bowel neoplasms in symptomatic patients, with conventional endoscopy, tissue specimen, capsule endoscopy, conventional enteroclysis, and follow-up findings as reference standards. MATERIALS AND METHODS The study protocol was approved by the human research committee, and all patients gave written informed consent. One hundred fifty patients (83 male, 67 female; mean age, 42.6 years; age range, 17-84 years) who were clinically suspected of having small-bowel neoplasm and whose previous upper and lower gastrointestinal endoscopy findings were normal underwent MR enteroclysis. The MR enteroclysis findings were prospectively evaluated for the presence of focal bowel wall thickening, small-bowel masses, and small-bowel stenosis. Positive MR enteroclysis findings were compared with histopathologic examination results obtained after surgical (n = 19) or endoscopic (n = 2) procedures. Negative MR enteroclysis results were compared with the results of enteroscopy (n = 5), capsule endoscopy (n = 53), or conventional enteroclysis with subsequent clinical follow-up (n = 71). The diagnostic performance of MR enteroclysis was analyzed on a per-patient basis. RESULTS MR enteroclysis was successfully completed in all 150 patients and enabled correct detection of 19 small-bowel neoplasms, which were confirmed at histopathologic examination: three carcinoid neoplasms, two adenocarcinomas, two stromal tumors, five lymphomas, one angiomatous mass, three small-bowel metastases, one leiomyoma, one adenoma, and one lipoma. Overall sensitivity, specificity, and accuracy in identifying patients with small-bowel lesions were 86% (19 of 22), 98% (126 of 128), and 97% (145 of 150), respectively. Two MR enteroclysis examinations yielded false-positive findings, and three yielded false-negative findings. CONCLUSION MR enteroclysis is an accurate modality for detecting small-bowel neoplasms in symptomatic patients.

Assessment of Crohn’s disease in the small bowel: prospective comparison of magnetic resonance enteroclysis with conventional enteroclysis

Our objective was to assess the diagnostic value of magnetic resonance enteroclysis (MRE) compared with conventional enteroclysis (CE) in patients with Crohn’s disease. A secondary objective was to evaluate the diagnostic accuracy of each different MR sequence. Sixty-six consecutive patients with known Crohn’s disease underwent MRE and CE. Fast imaging employing steady-state acquisition (FIESTA), single-shot fast spin-echo (ssFSE), and contrast-enhanced T1-weighted sequences were assessed by two radiologists who reached a consensus about the following findings: visualization of wall ulcers, pseudopolyps, fistulae, mural stenosis, and mesenteric abnormalities. Standard descriptive statistics and the McNemar test were used. The sensitivity, specificity and accuracy of MRE were 90–87% and 83% for the depiction of parietal ulcers, 84%–88% and 86% for pseudopolyps, 100–94% and 96% for mural stenosis, 93–100% and 94% for fistulae. The number of detected extraluminal findings was significantly higher with MRE (P<0.01). The accuracy of FIESTA sequence was statistically higher in the depiction of wall ulcers and fistulae than that of three-dimensional fast spoiled gradient echo (3D-FSPGR) (P<0.01) and ssFSE (P<0.05) sequences. Contrast-enhanced 3D-FSPGR was superior for mural stenosis visualization compared to ssFSE (P<0.05) and FIESTA (P<0.05). MRE correlates accurately with CE in the detection of superficial and transmural abnormalities and has the advantage of assessing the mesenteric manifestations.

Magnetic resonance imaging in the evaluation of placental adhesive disorders: correlation with color Doppler ultrasound

The purpose of this study was to compare the value of pelvic ultrasound with color Doppler and magnetic resonance imaging (MRI) in: (1) the diagnosis of placental adhesive disorders (PADs), (2) the definition of the degree of placenta invasiveness, (3) determining the topographic correlation between the diagnostic images and the surgical results. Fifty patients in the third trimester of pregnancy with a diagnosis of placenta previa and at least one previous caesarean section underwent color Doppler ultrasound (US) and MRI. The sonographic and MRI diagnoses were compared with the final pathologic or operative findings. Outcomes at delivery were as follows: normal placenta (n = 38) and PAD (n = 12). MR and US Doppler showed no statistically difference in identiyfing patients with PAD (P = 0.74), while MRI was statistically better than US Doppler in evaluating the depth of placenta infiltration (P < 0.001). MRI accurately characterized the topography of invasion in 12/12 (100%) of the cases, while US accurately characterized the topography of invasion in 9/12 (75%) of the cases. In conclusion, we confirmed that pelvic US is highly reliable to diagnose or exclude the presence of PAD and found MRI to be an excellent tool for the staging and topographic evaluation of PAD.

Dynamic MR imaging of the pelvic floor: a pictorial review.

Pelvic floor dysfunctions involving some or all pelvic viscera are complex conditions that occur frequently and primarily affect adult women. Because abnormalities of the three pelvic compartments are frequently associated, a complete survey of the entire pelvis is necessary for optimal patient management, especially before surgical correction is attempted. With the increasing use of magnetic resonance (MR) imaging in assessing functional disorders of the pelvic floor, familiarity with normal imaging findings and features of pathologic conditions are important for radiologists. Dynamic MR imaging of the pelvic floor is an excellent tool for assessing functional disorders of the pelvic floor such as pelvic organ prolapse, outlet obstruction, and incontinence. Findings reported at dynamic MR imaging of the pelvic floor are valuable for selecting patients who are candidates for surgical treatment and for choosing the appropriate surgical approach. This pictorial essay reviews MR imaging findings of pelvic organ prolapse, fecal incontinence, and obstructed defecation. Supplemental material available at http://radiographics.rsnajnls.org/cgi/content/full/e35v1/DC1.

MR imaging and MR cholangiopancreatography in the preoperative evaluation of hilar cholangiocarcinoma: correlation with surgical and pathologic findings

The primary aim was to evaluate delayed contrast-enhanced MRI in depicting perineural spread of hilar cholangiocarcinoma (CCC) and consequently to determine the capability of MRI/MRCP for staging CCC. Fifteen patients that underwent MRI/MRCP and surgical treatment were retrospectively included. Two radiologists evaluated MR images to assess delayed periductal enhancement, extent of bile duct stenosis, liver parenchymal and vascular involvement and presence of liver atrophy. An agreement between delayed enhancement of the bile duct walls and perineural neoplastic spread showed a very good correlation factor (0.93). The overall accuracy in detecting biliary neoplastic invasion was higher for delayed T1-weighted images (93.3%) than for the MRCP images (80%), and T1-delayed image increased the MR accuracy in assessing the neoplastic resectability (p < 0.05). MRI correctly predicted vascular involvement in 73% and liver involvement in 80% of the cases. The number of overall correctly assessed patients with regard to resectability was 11 true positive, 1 false positive and 3 true negative. The combination of MRI/MRCP is a reliable diagnostic method for staging hilar cholangiocarcinomas. Delayed periductal enhancement is accurate in the evaluation of neoplastic perineural spread, and it can improve diagnostic accuracy to identify resectable and unresectable tumours.

CT and MR enterography in evaluating small bowel diseases: when to use which modality?

MR and CT techniques optimized for small bowel imaging are playing an increasing role in the evaluation of small bowel disorders. Several studies have shown the advantages of these techniques over traditional barium fluoroscopic examinations due to improvements in spatial and temporal resolution combined with improved bowel distending agents. The preference of MR vs. CT has been geographical and based on expertise and public policy. With the increasing awareness of radiation exposure, there has been a more global interest in implementing techniques that either reduce or eliminate radiation exposure. This is especially important in patients with chronic diseases such as inflammatory bowel disease who may require multiple studies over a lifetime or in studies that require sequential imaging time points such as in assessment of gastrointestinal motility. MRI has many properties that make it well suited to imaging of the small bowel: the lack of ionizing radiation, the improved tissue contrast that can be obtained by using a variety of pulse sequences, and the ability to perform real time functional imaging. Moreover, MR modalities allow visualization of the entire bowel, without overlapping bowel loops, as well as the detection of both intra- and extraluminal abnormalities.The intra- and extraluminal MR findings, combined with contrast enhancement and functional information, help to make an accurate diagnosis and consequently characterize small bowel diseases.

Intralesional steroid injection after endoscopic balloon dilation in pediatric Crohn's disease with stricture: A prospective, randomized, double-blind, controlled trial

BACKGROUND Endoscopic balloon dilation (EBD) is an attractive conservative therapy for Crohns disease (CD) with stricture; however, its long-term efficacy has been questioned because many patients require more dilations or postdilation surgery. Most reports are retrospective, and no pediatric data are available. OBJECTIVE To assess the effectiveness of corticosteroid intralesional injection after EBD in preventing stricture recurrence. DESIGN Single-center prospective, randomized, double-blind, controlled trial. SETTING Tertiary-referral university hospital. PATIENTS Between November 2005 and January 2009, 29 pediatric patients with stricturing CD were enrolled. INTERVENTIONS Enrolled patients were randomized to receive intrastricture injection of corticosteroid (CS) (n = 15) or placebo (n = 14) after EBD. Patients were followed clinically via small intestine contrast US and intestinal magnetic resonance imaging at 1, 3, 6, and 12 months; all underwent colonoscopy 12 months after dilation. MAIN OUTCOME MEASUREMENTS Time free of repeat dilation and time free of surgery in the 2 groups. RESULTS One of the 15 patients receiving CS required redilation, whereas the latter was needed in 5 of the 14 placebo patients; surgery was needed in 4 of the placebo patients, but in none of those receiving CS. The 2 groups statistically differed in the time free of redilation (P = .04) as well as for time free of surgery after EBD (P = .02), which were worse in the placebo group compared with the CS group. There were no significant differences in baseline demographics between the 2 groups. LIMITATIONS Sample size, participation bias, and short-term follow-up. CONCLUSION In pediatric CD with stricture, intralesional CS injection after EBD is an effective strategy for reducing the need both for redilation and surgery.

MR enterography versus capsule endoscopy in paediatric patients with suspected Crohn's disease.

ObjectiveThe aim of this prospective study was to compare the diagnostic yield of MR enterography (MRE) with small-bowel capsule endoscopy (SBCE) in paediatric patients with suspected Crohn’s disease (CD).MethodsPaediatric patients with suspected CD were considered eligible to be enrolled in the study. All patients underwent diagnostic work-up including 1.5-T MRE, ileo-colonoscopy and oesophagogastroduodenoscopy. SBCE was not performed if MRE showed SB stricture or extra-intestinal findings consistent with symptoms.ResultsSixty consecutive paediatric patients (36 male; average age 14) were enrolled into the study. A positive diagnosis for CD was made in 19 patients, 29 had a negative result and 12 were affected by other gastro-intestinal conditions. SBCE was performed in 37 patients (61.7%); 23 patients were excluded (strictures in five, extra-intestinal findings in 11 and parents’ refusal in seven cases). The accuracy, sensitivity, and specificity of MRE and SBCE were 98.3%, 100%, 97.6%, and 91.9%, 90.9%, 92.3%, respectively.ConclusionBoth MRE and SBCE are accurate methods for patients with suspected CD. MRE can be used as a primary imaging technique in suspected CD, in that it allows access to the ileal stricture, which forms a contra-indication for SBCE and provides extra-intestinal information.

MR imaging of the placenta: what a radiologist should know

Imaging of the placenta can have a profound impact on patient management, owing to the morbidity and mortality associated with various placental conditions. Placental conditions affecting the mother and fetus include molar pregnancies, placental hematoma, abruption, previa, accreta, vasa previa, chorioangioma, and retained products of conception. Although uncommon, abnormalities of the placenta are important to recognize owing to the potential for maternal and fetal morbidity and mortality. Sonography remains the first imaging modality for evaluation of the placenta. Magnetic resonance (MR) imaging has many unique properties that make it well-suited for imaging of the placenta: the multi-planar capabilities, the improved tissue contrast that can be obtained using a variety of pulse sequences and parameters and the lack of ionizing radiation; MR imaging can be of added diagnostic value when further characterization is required. In this article, we review the appearances and the role of MRI in diagnosis and management of these conditions. We present our clinical perspective on diagnosing these challenging problems with MRI and review the imaging findings that can lead to a correct diagnosis.