Pictorial essay: improving diagnostic effectiveness of colorectal cancer at CT.

As the routine use for CT increases, there is an opportunity to increase the detection rate of unsuspected and asymptomatic colorectal cancers. This pictorial essay provides abundant examples of the typical morphologic appearances of colorectal cancer in the unprepared colorectum. Many examples of lesions that were missed in clinical practice are illustrated with lessons on how to avoid these errors. Atypical appearances of colorectal cancer are also illustrated. The overall aim is to increase the detection rate of colorectal cancer at routine CT.

Chemotherapy-associated liver morphological changes in hepatic metastases (CALMCHeM).

PURPOSE: To review imaging findings in chemotherapy-associated liver morphological changes in hepatic metastases (CALMCHeM) on computed tomography (CT)/magnetic resonance imaging (MRI) and its association with tumor burden. METHODS: We performed a retrospective chart review to identify patients with hepatic metastases who received chemotherapy and subsequent follow-up imaging where CT or MRI showed morphological changes in the liver. The morphological changes searched for were nodularity, capsular retraction, hypodense fibrotic bands, lobulated outline, atrophy or hypertrophy of segments or lobes, widened fissures, and one or more features of portal hypertension (splenomegaly/venous collaterals/ascites). The inclusion criteria were as follows: a) no known chronic liver disease; b) availability of CT or MRI images before chemotherapy that showed no morphological signs of chronic liver disease; c) at least one follow-up CT or MRI image demonstrating CALMCHeM after chemotherapy. Two radiologists in consensus graded the initial hepatic metastases tumor burden according to number (≤10 and >10), lobe distribution (single or both lobes), and liver parenchyma volume affected (<50%, or ≥50%). Imaging features after treatment were graded according to a pre-defined qualitative assessment scale of "normal," "mild," "moderate," or "severe." Descriptive statistics were performed with binary groups based on the number, lobar distribution, type, and volume of the liver affected. Chi-square and t-tests were used for comparative statistics. The Cox proportional hazard model was used to determine the association between severe CALMCHeM changes and age, sex, tumor burden, and primary carcinoma type. RESULTS: A total of 219 patients met the inclusion criteria. The most common primaries were from breast (58.4%), colorectal (14.2%), and neuroendocrine (11.0%) carcinomas. Hepatic metastases were discrete in 54.8% of cases, confluent in 38.8%, and diffuse in 6.4%. The number of metastases was >10 in 64.4% of patients. The volume of liver involved was <50% in 79.8% and ≥50% in 20.2% of cases. The severity of CALMCHeM at the first imaging follow-up was associated with a larger number of metastases (P = 0.002) and volume of the liver affected (P = 0.015). The severity of CALMCHeM had progressed to moderate to severe changes in 85.9% of patients, and 72.5% of patients had one or more features of portal hypertension at the last follow-up. The most common features at the final follow-up were nodularity (95.0%), capsular retraction (93.4%), atrophy (66.2%), and ascites (65.7%). The Cox proportional hazard model showed metastases affected ≥50% of the liver (P = 0.033), and the female gender (P = 0.004) was independently associated with severe CALMCHeM. CONCLUSION: CALMCHeM can be observed with a wide variety of malignancies, is progressive in severity, and the severity correlates with the initial metastatic liver disease burden.

Strategies for improving colorectal cancer detection with routine computed tomography.

PURPOSE: To report the detection rate of colorectal tumors with computed tomography (CT) performed within 1 year before diagnosis for indications other than colon abnormalities. Strategies to improve cancer detection are reported. METHODS: Two board-certified, subspecialty-trained abdominal radiologists retrospectively reviewed patient health records and CT images with knowledge of tumor location/size. Patients were classified into 3 groups: prospective (colon abnormality suggesting neoplasm documented in radiologic report), retrospective (not documented in radiologic report but detected in our retrospective review of CT images), and undetected (neither prospectively nor retrospectively detected). Retrospective detection confidence and morphologic characteristics of each tumor were also recorded. RESULTS: Of 209 included patients, 106 (50.7%) had prospectively detected tumors, 66 (31.6%) had retrospectively detected tumors, and 37 (17.7%) had undetected tumors. Asymmetric bowel wall thickening and polypoid masses were present more often in the retrospective group than in the prospective group (27% vs. 10.5% and 26% vs. 17.1%, respectively). Tumors in the ascending colon were more likely to be detected retrospectively than prospectively (odds ratio, 2.75; 95% CI 1.07-7.08; P = 0.04). Undetected tumors were smaller on average (2.9 cm) than prospective (6.0 cm) and retrospective (4.9 cm) tumors (P = 0.03). Detection confidence was lower for retrospectively detected tumors than for prospectively detected tumors (P = 0.03). Indications other than abdominal pain were most common for retrospectively detected tumors (P = 0.03). Use of intravenous contrast material was lowest in the undetected group (P = 0.003). The prospective group had more pericolonic abnormalities, regional/retroperitoneal lymph node involvement (P < 0.001), and distant metastases than did the retrospective group (P = 0.01). CONCLUSION: Half of all colorectal tumors were not detected prospectively. Radiologists should perform meticulous colon tracking regardless of the indication for CT. The right colon merits additional examination. Polypoid and asymmetric morphologic characteristics were most often overlooked, but these characteristics can be learned to improve detection.

Continent ileostomies: what the radiologist needs to know.

Continent ileostomies are performed in patients who are not candidates for or do not want a traditional J-pouch after total colectomy. In these cases, patients may opt for a type of continent ileostomy instead of an end ileostomy. The most common types of continent ileostomies include the Kock (K) pouch, S-pouch and Barnett Continent Intestinal Reservoir. The normal fluoroscopic and CT appearance of these types of continent ileostomies are reviewed. CT provides better evaluation of the proximal small bowel and pouch for inflammatory bowel disease, while fluoroscopy is superior in evaluating the nipple valve. Common complications of these types of continent ileostomies are discussed including slipped nipple valve, pouch inflammation, fistulas, and polyps. Radiologist should be familiar with the different types of continent ileostomies that exist and their common complications.

Imaging Review of Gastrointestinal Motility Disorders.

The motor function of the gastrointestinal tract relies on the enteric nervous system, which includes neurons spanning from the esophagus to the internal anal sphincter. Disorders of gastrointestinal motility arise as a result of disease within the affected portion of the enteric nervous system and may be caused by a wide array of underlying diseases. The etiology of motility disorders may be primary or due to secondary causes related to infection or inflammation, congenital abnormalities, metabolic disturbances, systemic illness, or medication-related side effects. The symptoms of gastrointestinal dysmotility tend to be nonspecific and may cause diagnostic difficulty. Therefore, evaluation of motility disorders requires a combination of clinical, radiologic, and endoscopic or manometric testing. Radiologic studies including fluoroscopy, CT, MRI, and nuclear scintigraphy allow exclusion of alternative pathologic conditions and serve as adjuncts to endoscopy and manometry to determine the appropriate diagnosis. Additionally, radiologist understanding of clinical evaluation of motility disorders is necessary for guiding referring clinicians and appropriately imaging patients. New developments and advances in imaging techniques have allowed improved assessment and diagnosis of motility disorders, which will continue to improve patient treatment options. Online supplemental material is available for this article. ©RSNA, 2022.

NSAID enteropathy: appearance at CT and MR enterography in the age of multi-modality imaging and treatment.

CT and MR enterography and capsule endoscopy are increasingly used as routine diagnostic tests for patients with potential small bowel disorders and obscure gastrointestinal bleeding. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used drugs that disrupt prostaglandin synthesis and result in a variety of localized complications within the small bowel ranging from ulcer formation to characteristic circumferential strictures, or diaphragms. NSAID enteropathy encompasses this spectrum of acute and chronic inflammatory sequelae, and is associated with typical findings at capsule endoscopy and surgery. Herein we review the typical clinical presentation of NSAID enteropathy, in addition to its endoscopic appearances, focusing on imaging findings at cross-sectional enterography. Multiple, short-segment strictures are the hallmarks of imaging diagnosis. Strictures may have minimal hyperenhancement or wall thickening, but these findings are typically symmetric and circumferential with respect to the bowel lumen. Multifocal Crohn's strictures, and occasionally radiation-induced strictures or adhesions, will mimic NSAID diaphragms. Multi-phase or multi-sequence imaging at CT and MR enterography increase diagnostic confidence in stricture presence. Strategies for subsequent workup and therapy after enterography are also discussed. Given the frequent use of NSAIDs and typical appearance of these strictures, knowledge of characteristic imaging findings can be particularly useful when evaluating patients with anemia and recurrent small bowel obstruction.

Abdominal imaging findings in gastrointestinal basidiobolomycosis.

PURPOSE: To describe the abdominal imaging findings of patients with gastrointestinal Basidiobolus ranarum infection. METHODS: A literature search was performed to compile the abdominal imaging findings of all reported worldwide cases of gastrointestinal basidiobolomycosis (GIB). In addition, a retrospective review at our institution was performed to identify GIB cases that had imaging findings. A radiologist aware of the diagnosis reviewed the imaging findings in detail. Additional information was obtained from the medical records. RESULTS: A total of 73 GIB cases have been published in the medical literature. The most common abdominal imaging findings were masses in the colon, the liver, or multiple sites and bowel wall thickening. Initially, many patients were considered to have either a neoplasm or Crohn disease. We identified 7 proven cases of GIB at our institution, of which 4 had imaging studies (4 computed tomography [CT] examinations, 4 abdominal radiographs, and an upper gastrointestinal study). Imaging studies showed abnormalities in all 4 cases. Three-fourths of our study patients had an abdominal mass at CT. Two of 3 masses involved the kidneys and included urinary obstruction. All masses showed an inflammatory component with adjacent soft tissue stranding, with or without abscess formation. CONCLUSIONS: Radiologists should consider GIB when a patient from an arid climate presents with abdominal pain, weight loss, and an inflammatory abdominal mass on CT. Abdominal masses of the colon or liver, bowel wall thickening, and abscesses are the most common imaging findings.

Diaphragm disease of the small bowel: a retrospective review of CT findings.

OBJECTIVE: The purpose of this article is to report the CT findings of pathologically proven diaphragm disease in the small bowel. MATERIALS AND METHODS: A retrospective review identified 12 patients with pathologically proven small-bowel diaphragm disease who underwent CT within 6 months of surgical resection. Two radiologists, who were unblinded to pathologic and clinical findings, evaluated CT examinations for imaging findings of disease extent, appearance, and location. Clinical history and postoperative follow-up were also performed. RESULTS: The most common presenting symptoms were abdominal pain (7/12 [58%]) and anemia (5/12 [42%]). Long-term use of nonsteroidal antiinflammatory drugs was documented in 58% (7/12) of patients. The most common location of small-bowel diaphragms was the ileum (8/12 [67%]). The CT findings were abnormal in 92% (11/12) of patients. The most common CT findings were small-bowel strictures (11/12 [92%]) and focal (median length, 1 cm) bowel wall thickening (8/12 [67%]). Other less common CT findings included mucosal hyperenhancement (6/12 [50%]), small-bowel dilatation (5/12 [42%]), and video capsule retention (6/9 [67%]). Postoperative follow-up in 11 patients found recurrent symptoms in four patients. CONCLUSION: Small-bowel diaphragm disease should be considered in patients with a history of long-term use of nonsteroidal antiinflammatory drugs, chronic abdominal pain, and anemia who present with CT findings of short, symmetric ileal strictures and focal bowel wall thickening.

Reducing the radiation dose for CT colonography using adaptive statistical iterative reconstruction: A pilot study.

OBJECTIVE: The purpose of our study was to evaluate the feasibility of preserving image quality during CT colonography (CTC) using a reduced radiation dose with adaptive statistical iterative reconstruction (ASIR). MATERIALS AND METHODS: A proven colon phantom was imaged at standard dose settings (50 mAs) and at reduced doses (10-40 mAs) using six different ASIR levels (0-100%). We assessed 2D and 3D image quality and noise to determine the optimal dose and ASIR setting. Eighteen patients were then scanned with a standard CTC dose (50 mAs) in the supine position and at a reduced dose of 25 mAs with 40% ASIR in the prone position. Three radiologists blinded to the scanning techniques assessed 2D and 3D image quality and noise at three different colon locations. A score difference of > or = 1 was considered clinically important. Actual noise measures were compared between the standard-dose and low-dose acquisitions. RESULTS: The phantom study showed image noise reduction that correlated with a higher percentage of ASIR. In patients, no significant image quality differences were identified between standard- and low-dose images using 40% ASIR. Overall image quality was reduced for both image sets as body mass index increased. Measured image noise was less with the low-dose technique using ASIR. CONCLUSION: The results of this pilot study show that the radiation dose during CTC can be reduced 50% below currently accepted low-dose techniques without significantly affecting image quality when ASIR is used. Further evaluation in a larger patient group is warranted.