Francesca Maccioni

Metallic stents in benign biliary strictures: Three-year follow-up

Eighteen patients with recurrent benign biliary strictures (BBS) were selected for metallic stents placement because they failed to respond to percutaneous balloon dilatation. None were candidates for surgical corrections. We used “Z” single or double stents in 17 cases and a Wallstent in 1 case. After more than 3 years of follow-up (average period 37 months, range 30–41 months), 10 patients (55.5%) were asymptomatic without signs of bile statis; 5 patients (27.7%) had recurrence of symptoms and were eventually retreated; and 3 patients (16.6%) died, 2 of obstructive jaundice and liver failure and 1 of metastatic gastric cancer. Recurrence was due to stent occlusion by tissue ingrowth in 3 cases, stent migration in 1 case, and an inflammatory lesion of the papilla of Vater in another case, with patency of the metallic stent. The overall patency rate, at 3-year follow-up was 68.7%. In our series, the main factor determining long-term patency of metallic stents has been reactive tissue ingrowth. Nevertheless, long-term results obtained with metallic stents in recurrent benign biliary strictures should be considered satisfactory. In selected patients, metallic stents may represent the only long-term treatment available for maintaining bile flow.

MRI evaluation of Crohn's disease of the small and large bowel with the use of negative superparamagnetic oral contrast agents.

Crohn’s disease (CD) is a chronic inflammatory disorder of the bowel wall; it starts in the submucosal layer and progresses to the entire wall and beyond it, leading to a diffuse perivisceral inflammation, adhesions, fissures, fistulas, and abscesses. For this typical transmural and extramural course, most of its findings (wall thickening and enhancement, fibrofatty proliferation, phlegmons, abscesses, etc) can be directly detected and evaluated only with the use of cross-sectional imaging techniques rather with than barium studies [1–4]. In the past few years, the evaluation of CD with sectional imaging modalities such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) has significantly explanded the spectrum of information about the disease and changed its diagnostic workup. Radiologic barium studies such as small bowel followthrough and enteroclysis are projection techniques that focus on lumenal abnormalities. Thanks to their highspatial resolution, these modalities can image the inner profile of the wall and thus detect all the main mucosal changes of CD [5, 6]. Conversely, the effects of the changes produced by CD in the outer wall layers and contiguous tissues can be evaluated only indirectly by radiologic barium studies. Cross-sectional modalities have added a third spatial dimension, thus allowing visualization of the disease “outside of the lumen.” For many years, MRI, has been used mainly to assess anal and perianal CD abnormalities [7, 8]. In fact, the slow acquisition times of early MRI systems caused severe image degradation due to peristaltic and respiratory movements throughout the abdomen, except in the pelvis, thus limiting the evaluation of the small and large bowel. The recent technical improvements of MRI systems have greatly increased the diagnostic possibilities of abdominal MRI, particularly in the study of the intestinal wall. At present, fast acquisition techniques significantly reduce motion artifacts and provide excellent dynamic contrast-enhanced studies of the bowel wall. The simultaneous increase of spatial resolution achieved by phased array or the newer body coils has further improved the diagnostic accuracy of MRI in the evaluation of the bowel wall. The recent possibility of signal modulation, e.g., by selectively suppressing the fat signal, has led to unexpected results in body imaging. Further, positive and negative oral contrast agents are now commercially available. All these technical improvements have spontaneously expanded the application of MRI in inflammatory bowel diseases, and numerous recent studies have documented this increasing interest in the investigation of the full range of CD abnormalities with the newest MRI techniques [9–25]. Several techniques have been proposed for the assessment of CD and other inflammatory bowel diseases. One is based on the nasojejunal intubation, the so-called MR enteroclysis [9–13], which can be performed with positive or negative oral contrast agents. The goal of this technique is to obtain more detailed information on lumenal abnormalities by bowel distention, in a manner similar to conventional enteroclysis. Other techniques are based on the oral administration of contrast agents rather than on nasojejunal intubation. In general, these techniques try to optimize the cross-sectional multiplanar evaluation of CD based on the belief that the intrinsic transmural and extramural courses of the disease mainly require a direct evaluation of wall changes and perivisceral abnormalities rather than of lumenal abnormalities [14–25]. Many of the CD findings observed on axial and coronal MR images are similar to those described on CT, whereas others are completely new and inherent to MRI. Correspondence to: F. Maccioni Abdom Imaging 27:384–393 (2002) DOI: 10.1007/s00261-001-0119-3 Abdominal Imaging

Ulcerative colitis : value of MR imaging

Recent technologic advances have greatly improved the quality of abdominal magnetic resonance imaging (MRI) by allowing the identification of abnormalities in inflammatory bowel disease. Thus far, the role of MRI has been extensively investigated in Crohn disease (CD) and, to a minor extent, in ulcerative colitis (UC), likely due to intrinsic differences between these two diseases. In UC the inflammatory lesions, unlike CD, are confined to the colon, have a predictable spreading, and affect only the inner wall layer; thus endoscopy alone can assess the extent and severity of disease in most cases. However, preliminary studies have demonstrated that MRI also can be a reliable diagnostic tool for UC because it is useful for integrating clinical and endoscopic data. MRI can be valuable in distinguishing CD from UC in uncertain cases by assessing the sparing of the distal ileum and the continuity of colonic involvement. Moreover, MRI can provide important information if endoscopy is incomplete, e.g., due to tight strictures, or contraindicated, e.g., in severely acute disease, due to a high risk of perforation. MRI can detect most of the typical findings of the diseases, such as wall thickening, mural stratification, loss of haustrations, and several complications including fibrotic or neoplastic strictures. In addition, MRI can be extremely valuable in assessing disease activity by monitoring the degree of wall gadolinium enhancement and T2 signal at the level of the affected bowel segments, thus influencing pharmacologic and surgical planning. In the next few years, MRI will likely become the imaging modality of choice in the clinical management of this disease.

Oral contrast agents in MRI of the gastrointestinal tract.

The role of magnetic resonance imaging (MRI) for abdominal imaging is still controversial, given the simultaneous presence of many potential benefits and some technical limitations. On the one hand, MRI is an expensive but risk-free procedure; it provides high-quality images in any plane, shows a very high sensitivity to tissue differences, and can demonstrate vessels and flow or detect absence of flow without injection of contrast materials. On the other hand, the application of MRI in abdominal imaging is limited by several problems such as peristaltic, respiratory, cardiac, and pulsatile flow motion artifacts. Recent advances in rapid imaging techniques and the implementation of torso phased array coils, which allow high-quality breath-hold imaging with high spatial resolution, have extended the role of MRI in evaluating abdominopelvic disease and gastrointestinal (GI) tract function. [1–3]. Although MRI has became an important technique for liver and pancreas imaging, its potential role in GI tract studies remains a matter of debate. As with computed tomography (CT), the need for bowel opacification with the use of oral contrast medium is mandatory to differentiate between collapsed or fluid-filled bowel loops and intra-abdominal organs or pathologic lesions. For many years, the lack of a widely available oral contrast agent has been stated as the primary cause of the limited use of MRI in GI tract evaluation. Nowadays oral MR contrast agents are commercially available but still not used routinely in most departments. We summarize the basic applications of MR oral contrast agents and their main clinical applications in GI tract evaluation. MR oral contrast agents

New frontiers of MRI in Crohn’s disease: motility imaging, diffusion-weighted imaging, perfusion MRI, MR spectroscopy, molecular imaging, and hybrid imaging (PET/MRI)

This article reviews the latest diagnostic advances in the evaluation of the CD, including functional studies on intestinal motility and molecular characterization of the inflammatory process at the level of the involved bowel. Molecular changes related to inflammation of the intestinal wall may be evaluated by different MRI techniques, including diffusion-weighted imaging, perfusion weighted imaging, in vivo spectroscopy, molecular imaging, and fusion imaging (PET–MRI).

Hydro-CT in patients with gastric cancer: Preoperative radiologic staging

A total of 35 patients (age range 35–78 years) with gastric tumors on the lesser curve, or in the antro-pyloric region, underwent angio-CT in the prone position after filling the stomach with 500 ml of water and intravenous administration of glucagon. The films were reviewed by three radiologists independently, staging each tumor according to the TNM classification preoperatively. The overall accuracy of tumor staging ranged between 66–77%, overstaging between 17–25%, and understaging between 3–8.5%. The diagnostic sensitivity, specificity, and accuracy for serosal invasion ranged between 90 and 100, 76 and 84, and 80–88%, respectively, and the overall accuracy for N staging was 46, 48, and 51% for the three observers. If, however, N1 and N2 tumors were considered as a single group, N-stage accuracy increased, ranging between 63 and 77%. The “K test” for analyzing the interobserver agreement was 60%, i.e., the diagnostic results are reproducible. Water filling of the stomach optimizes visualization of the gastric wall on contrast-enhanced CT. The prone position and drug-induced hypotony allows for good distension without any disturbing artifact reduction obscuring the lower gastric body.

Imaging of cell trafficking in Crohn's disease.

Inflammatory bowel diseases are represented by ulcerative colitis and Crohns disease, both consisting of a chronic, uncontrolled inflammation of the intestinal mucosa of any part of the gastrointestinal tract with patchy or continuous inflammation. Ileo‐colonoscopy is considered the current gold standard imaging technique for the diagnosis. However, as the majority of patients need a long‐term follow‐up it would be ideal to rely on a non‐invasive technique with good compliance. This review focuses on nuclear medicine imaging techniques in Crohns disease. Different scintigraphic methods of imaging cells involved in the pathogenesis are described. The radiopharmaceuticals can be divided into non‐specific radiopharmaceuticals for inflammation and specific radiopharmaceuticals that directly image lymphocytes involved in the process. This non‐invasive molecular imaging approach can be useful also because it images the small bowel or other areas––where colonoscopy is not useful—and that it may play a role for constant follow‐up, because relapses are frequent. Finally, an update on other imaging modalities, and particularly MRI, in the evaluation of Crohns disease activity, is provided. Although MRI cannot directly detect inflammatory cells, it has shown a high sensitivity in detecting the macroscopic signs of inflammation at the level of the intestinal wall affected by Crohns disease and Ulcerative colitis. The current diagnostic value of MRI in the detection of inflamed bowel segment and in the assessment of CD activity, as well the potentials MR spectroscopy, MR diffusion imaging and MR molecular imaging, is briefly discussed. J. Cell. Physiol. 223:562–571, 2010.

Value of T2-weighted magnetic resonance imaging in the assessment of wall inflammation and fibrosis in Crohn’s disease

This review focuses specifically on the diagnostic value of T2-weighted imaging in the assessment of Crohn’s disease (CD) inflammation. In general, T2-weighted imaging has been less extensively investigated than T1-weighted gadolinium-enhanced imaging, even if it may offer similar information on disease activity. Furthermore, T2-weighted imaging allows CD characterization, which is crucial in the management of the disease when differentiating intestinal edema from fibrosis. Technical aspects, morphological findings and signs of active intestinal inflammation and fibrosis detectable on T2-weighted images will be reviewed and shown. Correlation between T2-weighted imaging findings, clinical activity indexes and histopathology features will be discussed. Since T2-weighted imaging is essential in the evaluation of CD activity, it should always complement with T1-weighted imaging, although it could also be used alone in the assessment of CD.

Detection of Crohn Disease Lesions of the Small and Large Bowel in Pediatric Patients: Diagnostic Value of MR Enterography Versus Reference Examinations

OBJECTIVE The purpose of this article is to prospectively determine the accuracy of MR enterography in detecting Crohn disease lesions from the jejunum to the anorectal region in pediatric patients, in comparison with main reference investigations. SUBJECTS AND METHODS Fifty consecutive children with known Crohn disease underwent MR enterography with oral contrast agent and gadolinium-chelate intravenous injection. Two radiologists detected and localized lesions by dividing the bowel into nine segments (450 analyzed segments in 50 patients). Ileocolonoscopy, barium studies, intestinal ultrasound, and capsule endoscopy were considered as first- and second-level reference examinations and were performed within 15 days of MR enterography. RESULTS MR enterography detected lesions in 164 of 450 segments, with 155 true-positive and nine false-positive findings; overall sensitivity, specificity, and positive and negative predictive values for small- and large-bowel lesions were 94.5%, 97%, 94.5%, and 97%, respectively (ĸ = 0.93; 95% CI, 0.89-0.97). Sensitivity and specificity values were 88% and 97%, respectively, for the jejunum, 100% and 97% for the proximal-to-mid ileum, 100% and 100% for the distal ileum, 93% and 100% for the cecum, 70% and 97% for the ascending colon, 80% and 100% for the transverse colon, 100% and 92% for the descending colon, 96% and 90% for the sigmoid colon, and 96% and 88% for the rectum. From jejunum to rectum, the AUC value ranged between 0.916 (jejunum) and 1.00 (distal ileum). Perianal fistulas were diagnosed in 15 patients, and other complications were found in 13 patients. CONCLUSION MR enterography showed an accuracy comparable to that of reference investigations, for both small- and large-bowel lesions. Because MR enterography is safer and more comprehensive than the reference examinations, it should be considered the primary examination for detecting Crohn disease lesions in children.

Double-contrast magnetic resonance imaging of the small and large bowel: effectiveness in the evaluation of inflammatory bowel disease

Double-contrast magnetic resonance imaging (DC-MRI) is a technique for imaging the intestine, which has shown to be very effective in assessing inflammatory bowel disease (IBD), and particularly Crohn’s disease (CD). The expression derives from the association of two different contrast agents, a superparmagnetic intestinal and a paramagnetic intravenous contrast agent. This specific contrast media combination provides optimization of the tissue contrast, both on T1- and T2-weighted images, thus allowing an effective display of small and large bowel loops in normal and pathologic conditions. Therefore, main CD complications (strictures, fistulas, and abscesses), as well as disease activity, may be valuably assessed. The term DC-MRI may also be referred to the typical “double contrast” effect that is produced by this technique at the level of the inflamed bowel wall, both on T1- and T2-weighted images, directly related to the degree of wall inflammation (disease activity).