Jaroslaw N. Tkacz

MR Imaging in Gastrointestinal Emergencies

Accurate and rapid diagnostic imaging is essential for the appropriate management of acute gastrointestinal conditions. Computed tomography (CT) is the modality most often used in this setting because of its widespread availability and the relative speed, ease, and uniformity with which evaluations can be performed. CT allows the diagnosis of a wide spectrum of acute gastrointestinal diseases with the adjustment of only a few variables in the acquisition protocol. For example, the contrast material volume, injection rate, and delay before image acquisition can be manipulated to enhance vascular or organ-specific contrast for myriad gastrointestinal diagnoses. Magnetic resonance (MR) imaging has similarly robust potential, although its integration into the acute care setting requires greater technical and logistical effort. Improved MR imaging sequences, advances in coil technology, streamlined imaging protocols, and increased technical and professional familiarity with the modality make it an increasingly attractive option when there is concern about patient radiation exposure or allergy to iodinated contrast material. A variety of acute abdominal conditions, including pancreatic and biliary tract trauma, choledocholithiasis, gallbladder disease, acute pancreatitis, and appendicitis can be rapidly and accurately demonstrated with MR imaging. MR imaging also can play a vital role in the follow-up assessment of treatment response and in the diagnosis of indeterminate findings at CT or ultrasonography. Nevertheless, incompatibility of patient monitoring devices with the MR magnet, lack of MR imaging system availability, and the acuity of illness may limit the use of the modality.

Ileal Pouch–Anal Anastomosis Surgery: Imaging and Intervention for Post-operative Complications

Ileal pouch-anal anastomosis (IPAA) surgery preserves fecal continence for improved quality of life in patients who require proctocolectomy for treatment of severe bowel diseases such as inflammatory disease and familial adenomatous polyposis. In IPAA surgery, an ileal reservoir, or pouch, is created and anastomosed to the anal canal. Awareness of the surgical technique and the postoperative anatomy of the IPAA is important to identify complications at computed tomography (CT), magnetic resonance (MR) imaging, and fluoroscopy. Complications include anastomotic leak, abscess, pouchitis, venous thrombus, pouch fistula, and stricture. Leaks from the blind end of the pouch and the pouch-anal anastomosis often result in pelvic abscesses, which may require ultrasonography- or CT-guided drainage; judicious catheter management can help improve clinical outcomes and avoid excessive imaging. Pouchitis may be identified by the presence of a thickened enhancing pouch wall and associated inflammatory changes and lymphadenopathy. The venous system must be scrutinized for thrombi secondary to surgical manipulation and sepsis. Fistulas are likely because of the presence of chronic inflammation or infection and may be seen at MR imaging, CT, or fluoroscopy. Strictures appear as areas of focal luminal narrowing with proximal dilatation, which can lead to obstruction. To avoid repeated exposure to radiation, MR imaging may be performed in patients who must undergo frequent imaging.

Gastroenteropancreatic neuroendocrine tumors: multimodality imaging features with pathological correlation

Neuroendocrine tumors of the gastrointestinal tract are rare entities. Functioning neuroendocrine tumors tend to present early because of hormoneinduced clinical symptoms, but detection of the primary lesion may be difficult owing to their small size. Neuroendocrine tumors are typically hypervascular and show enhancement after contrast administration on computed tomography (CT) or magnetic resonance imaging (MRI). Large nonfunctioning tumors may be found in asymptomatic patients. In such cases, the synchronous presence of hypervascular hepatic metastases should be explored. This pictorial review illustrates imaging features of functioning and nonfunctioning neuroendocrine tumors arising in the gastrointestinal tract and the pancreas. Modalities included are CT, MRI, ultrasonography, and nuclear medicine. Characteristic histological specimens of these lesions are presented.

Portal venous gas after colonoscopy in two patients with Crohn's disease

contrast medium to explore the precise entrance of the afferent loop. It should be emphasized that the image we saw on balloon-assisted enterography was more helpful for ERCP in patients after GI surgery. It helps the endoscopist see the altered structure clearly and allows the endoscope to move more smoothly along the digestive duct and minimize accidental injury to the intestinal wall (Fig. 2). For jejunojejuno anastomosis, the retrieval balloon catheter can also be stationed in the afferent loop as a guide to keep the duodenoscope from sliding out of the right loop (Fig. 3).

Complications of Esophageal Surgery: Role of Imaging in Diagnosis and Treatments

Esophageal surgery is a common and integral component in the management of hiatal hernias, esophageal carcinoma, and esophageal perforation. Understanding the expected postsurgical imaging features of these common esophageal surgeries and postoperative complications is essential. Image-guided intervention can be used to aid the surgeon in the management of many post esophageal surgical complications. We discuss the imaging features of the postoperative esophagus and the use of imaging, including fluoroscopy and computed tomography, in the diagnosis of post esophageal surgical complications and treatment.

Screening Breast MR Imaging for High-Risk Women: Should It Be Routine?

Women with certain risk factors are at higher risk for developing breast cancer in their lifetime. Although mammography is the only screening test proven to reduce mortality from breast cancer, many centers rely on other modalities to screen high-risk women. Because MR imaging has a high sensitivity for the detection of breast cancer, it is a promising complementary examination for screening women at highest risk for breast cancer, especially those women who are known carriers of one of the breast cancer genes or who have received high-dose radiation to the chest at a young age.

Evaluation of T1/T2 ratios in a pilot study as a potential biomarker of biopsy: proven benign and malignant breast lesions in correlation with histopathological disease stage

Aim: Early breast cancer detection is important for intervention and prognosis. Advances in treatment and outcome require diagnostic tools with highly positive predictive value. Purpose: To study the potential role of quantitative MRI (qMRI) using T1/T2 ratios to differentiate benign from malignant breast lesions. Methods: A cross-sectional study of 69 women with 69 known or suspicious breast lesions were scanned with mixed-turbo spin echo pulse sequence. Patients were grouped according to histopathological assessment of disease stage: untreated malignant tumor, treated malignancy and benign disease. Results & Discussion: Elevated T1/T2 means were observed for biopsy-proven malignant lesions and for malignant lesions treated prior to qMRI with chemotherapy and/or radiation, as compared with benign lesions. The qMRI-obtained T1/T2 ratios correlated with histopathology. Analysis revealed correlation between elevated T1/T2 ratio and disease stage. This could provide valuable complementary information on tissue properties as an additional diagnostic tool.