What’s new in Gastrointestinal Imaging – August 2020

9 months ago
IgG4‑related disease in the abdomen and pelvis: atypical findings, pitfalls, and mimics

Zheng Y, Elsayes KM, Waranch C, et al. IgG4-related disease in the abdomen and pelvis: atypical findings, pitfalls, and mimics. Abdom Radiol (NY). 2020;45(8):2485-2499. doi:10.1007/s00261-020-02526-2

https://link.springer.com/article/10.1007/s00261-020-02526-2

Keywords: Diagnostic approach, IgG4, autoimmune pancreatitis

Zheng et al. present an imaging review of IgG4-related disease. Radiologists play a central role in diagnosing IgG4-related disease, and this article discusses the expected imaging features of IgG4-related autoimmune pancreatitis, sclerosing cholangitis, renal disease, and retroperitoneal fibrosis. Additionally, the article details less common involvement such as hepatic, appendiceal, and prostatic. The article then describes management of IgG4-related disease with a combination of glucocorticoids and immunosuppressants, such as azathioprine or methotrexate, achieving up to a 98% remission rate, however, also with a 23% relapse rate.

 

Imaging of acute abdomen in cancer patients

Morani AC, Hanafy AK, Marcal LP, et al. Imaging of acute abdomen in cancer patients. Abdom Radiol (NY). 2020;45(8):2287-2304. doi:10.1007/s00261-019-02332-5

https://link.springer.com/content/pdf/10.1007%2Fs00261-019-02332-5.pdf

Keywords: Diagnostic approach, acute abdomen, oncology

In this review article, Morani et al. discuss abdominal emergencies in cancer patients. The article mentions that pain in this patient population may be due to the underlying malignancy, secondary to cancer therapy, or possibly from standard pathologies which cause an acute abdomen in the, otherwise, healthy patient population. The most common acute abdominal complaints in cancer patients are related to the gastrointestinal system, with some of the major pathologies including intestinal obstruction, perforation, ischemia, and inflammatory processes. Acute hepatic, pancreatic, biliary, genitourinary, and vascular etiologies are also covered. The article reviews common imaging patterns of common pathologies resulting in acute abdomen in this patient population, most frequently done with a contrast enhanced CT of the abdomen and pelvis. It also mentions that an acute abdomen may be the first manifestation of underlying malignancy, and as cancer patients live longer due to advances in treatment, the number of abdominal oncologic emergencies will continue to increase.

 

Contrast-Enhanced CT for the Diagnosis of Acute Mesenteric Ischemia

Garzelli L, Nuzzo A, Copin P, et al. Contrast-Enhanced CT for the Diagnosis of Acute Mesenteric Ischemia. AJR Am J Roentgenol. 2020;215(1):29-38. doi:10.2214/AJR.19.22625

https://www.ajronline.org/doi/abs/10.2214/AJR.19.22625

Keywords: Diagnostic approach, acute abdomen, mesenteric ischemia

This multi-institutional article provides an overview of the diagnostic and prognostic role of CT in the management of acute mesenteric ischemia (AMI). The article describes the pathophysiology, etiologies with associated CT appearances, and the clinical presentation of AMI.  The need for urgent intervention is discussed, as AMI has a mortality of nearly 100% if left untreated with untreated mortality rates dramatically increasing from 12% within the first 12 hours of symptoms to 98% after 48 hours. Contrast-enhanced CT is the most accurate technique for diagnosis of AMI, with specificity above 90%. CT is also beneficial in making alternative diagnoses in patients whom AMI was initially suspected. The article discusses the optimal CT protocol, which includes non-contrast, arterial, and portal venous phases. Imaging findings of AMI are then detailed, including bowel wall thinning or thickening, bowel wall hyperattenuation on unenhanced images, decreased bowel enhancement on post-contrast phases, and bowel dilation. Late AMI with irreversible transmural necrosis is differentiated from early AMI with reversible lesions by the presence of any of the following: organ failure, elevated serum lactate, and CT-evident bowel necrosis. The article concludes by discussing treatment options, including endovascular or surgical, and how CT plays a role in stratifying the need for revascularization or bowel resection.

 

Accuracy of magnetic resonance imaging in predicting dentate line invasion in low rectal cancer

Tatsumoto S, Itoh T, Takahama J, et al. Accuracy of magnetic resonance imaging in predicting dentate line invasion in low rectal cancer. Jpn J Radiol. 2020;38(6):539-546. doi:10.1007/s11604-020-00933-5

https://link.springer.com/article/10.1007/s11604-020-00933-5

Keywords: MRI, diagnostic approach, rectal cancer

This retrospective study assesses the accuracy of MRI in predicting dentate line invasion in patients with low rectal cancer. The article describes the dentate line as being an important landmark for surgical planning, with the landmark’s involvement oftentimes serving as a deciding factor in whether the patient undergoes a sphincter-preserving surgery versus an abdominoperineal resection. Two radiologists independently studied 54 patients with primary low rectal cancer and correctly identified dentate line invasion in 94% and 91% of patients, respectively. The article mentions the radiologically measured distance between the tumor and the MRI-defined dentate line was 4.9 mm shorter than the histologically determined distance, a discrepancy possibly due to difficulty interpreting the transition zone or inflammation around the tumor.

 

Small Bowel Neoplasms: A Pictorial Review

Jasti R, Carucci LR. Small Bowel Neoplasms: A Pictorial Review. Radiographics. 2020;40(4):1020-1038. doi:10.1148/rg.2020200011

https://pubs.rsna.org/doi/10.1148/rg.2020200011

Keywords: Diagnostic approach, review, small bowel

This review article gives an overview of benign and malignant small bowel neoplasms. The article begins with the epidemiology of small bowel neoplasms, which are rare and account for 0.5% of all cancers in the United States. However, the incidence of small bowel neoplasms is increasing, possibly due to increased identification of these tumors due to an increasing number of cross-sectional imaging studies performed for other indications.  The article discusses the evolution of small bowel imaging from the small bowel follow-through fluoroscopic imaging to cross sectional imaging, including CT and MR enterography. Aside from polyposis syndromes, benign small bowel tumors are usually solitary and include adenomas, hamartomas, lipomas, leiomyomas, and benign gastrointestinal stromal tumors (GISTs). Malignant small bowel neoplasms include malignant GISTs, adenocarcinoma, carcinoid, lymphoma, sarcoma, and metastasis.

 

Review of the N Category in the Updated TNM Staging of Cancers of the Digestive System. 

Pedersen CK, Babu AS. Understanding the Lymphatics: Review of the N Category in the Updated TNM Staging of Cancers of the Digestive System. AJR Am J Roentgenol. 2020;215(1):58-68. doi:10.2214/AJR.19.22636

https://www-ajronline-org/doi/abs/10.2214/AJR.19.22636

Keywords: Review, staging, oncology

This article gives a detailed look at the changes in the newly updated 8th edition of the AJCC TNM classification for cancers of the abdomen, including the digestive from the esophagus to the anal canal, hepatobiliary system, kidneys, and adrenal glands. Detection of lymph node involvement can be challenging, and this article details common lymphatic drainage pathways and nodal characteristics to ensure accurate staging, prognosis, and management. When lymph node metastases are present, it is important to note if the affected nodes are regional or nonregional; this article delineates the different nodal characteristics for cancers along the digestive and hepatobiliary tracts.

 

A radiomics-based model for prediction of lymph node metastasis in gastric cancer

Gao X, Ma T, Cui J, et al. A radiomics-based model for prediction of lymph node metastasis in gastric cancer. Eur J Radiol. 2020;129:109069. doi:10.1016/j.ejrad.2020.109069

https://www.sciencedirect.com/science/article/pii/S0720048X20302588

Keywords: Radiomics, gastric cancer, CT

This retrospective study introduces radiomics as the method of extracting quantitative data from medical images in an attempt to characterize, for example, cellular features or gene expression from imaging. This paper uses radiomics in gastric cancer to predict the presence of lymph node metastasis using contrast-enhanced CT imaging. The study looked at 768 patients who underwent radical gastrectomy and used variables such as age, sex, tumor location (fundus, body, antrum), pathologic T and N stage, CEA levels, and CA 19-9 levels. Using this data, the authors created a model to predict nodal metastasis. The authors demonstrated that upon histologic review, the radiomics data was able to better predict nodal metastasis when compared to just CT images alone.

 

Esophageal variceal hemorrhage: the role of MDCT characteristics in predicting the presence of varices and bleeding risk

Salahshour F, Mehrabinejad MM, Rashidi Shahpasandi MH, et al. Esophageal variceal hemorrhage: the role of MDCT characteristics in predicting the presence of varices and bleeding risk. Abdom Radiol (NY). 2020;45(8):2305-2314. doi:10.1007/s00261-020-02585-5

https://link.springer.com/content/pdf/10.1007/s00261-020-02585-5.pdf

Keywords: Cirrhosis, CT, Varices

This retrospective study looked at the efficacy of CT in identifying and predicting the presence esophageal varices when compared with endoscopy. The article discussed the epidemiology of varices and their increasing prevalence due to the increasing incidence of cirrhosis. In a population of 124 patients with cirrhosis of varying etiologies who underwent CT and upper endoscopy, CT had a 63% sensitivity and 82% specificity in detecting high-risk varices seen on endoscopy. Data analysis illustrated statistically significant associations between endoscopy-confirmed varices and coronary, short gastric, and paraesophageal collaterals. Notable variables not associated with the presence of varices included para-umbilical and splenorenal collaterals, splenomegaly, and IVC diameter. A relatively small sample size limited this study.

 

MDCT in the Setting of Suspected Colonic Diverticulitis: Prevalence and Diagnostic Yield for Diverticulitis and Alternative Diagnoses

Weinrich JM, Bannas P, Avanesov M, et al. MDCT in the Setting of Suspected Colonic Diverticulitis: Prevalence and Diagnostic Yield for Diverticulitis and Alternative Diagnoses. AJR Am J Roentgenol. 2020;215(1):39-49. doi:10.2214/AJR.19.21852

https://www.ajronline.org/doi/abs/10.2214/AJR.19.21852

Keywords: Retrospective study, diverticulitis, original research

This retrospective study aimed to detail statistics of colonic diverticulitis. The authors looked at 1069 CT scans in patients suspected of having diverticulitis and found 52.5% (561/1069) of the cohort with diverticulitis, with 39.9% (427/1069) having alternative diagnoses and 7.6% (81/1069) without a final diagnosis. The most common alternative diagnoses were appendicitis, infectious colitis, infectious gastroenteritis, urolithiasis, and pyelonephritis. The authors stratified positive cases of diverticulitis by age, sex, and admission status. Additionally, the authors evaluated the accuracy of CT in diagnosing colonic diverticulitis. Of the 561 patients with diverticulitis by colonoscopy or surgery, 556 were seen on CT to have diverticulitis by colonoscopy or surgery, for a sensitivity of 99.1%. CT correctly excluded acute colonic diverticulitis in 507 of 508 patients for a specificity of 99.8%. The article concluded by noting only approximately half of patients with suspected diverticulitis proved to have the disease, emphasizing the importance of considering alternative diagnoses.

 

Imaging of Abdominal Wall Masses, Mass-like Lesions, and Diffuse Processes

Ballard DH, Mazaheri P, Oppenheimer DC, et al. Imaging of Abdominal Wall Masses, Mass-like Lesions, and Diffuse Processes. Radiographics. 2020;40(3):684-706.

https://pubs.rsna.org/doi/pdf/10.1148/rg.2020190170

Keywords: Diagnostic approach, soft tissue masses, abdominal wall

This article presents an algorithmic approach to abdominal wall masses. The article suggests the first step in evaluating an abdominal wall mass is to ensure it is not a mass-like process such as a hernia. After determining the lesion as a discrete mass, the next step in the algorithm is to determine if there is a solitary lesion or multiple. Next, characterize the composition as fat, fluid, or solid, After these three steps of the algorithm have been completed, clinical history can help narrow the differential. Fat-containing masses are primarily benign lipomas with less common considerations including liposarcoma, hemangiomas, and arteriovenous malformations. Fluid-containing masses can be broadly characterized into three groups, hematomas, post-operative fluid collections, and cystic masses in patients without a history of surgery. These may be differentiated from one another by location, imaging characteristics and clinical history. Cystic lesions without a history of surgery include epidermal cysts and myxomas. Solid masses have a broad differential, and the interpreter should adjust the differential with relevant medical history. Metastasis should be considered in patients with a known underlying malignancy.

References
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