What’s New in Gastrointestinal Imaging? – July 2023

12 months ago

Radiology Residents’ Independent Diagnosis of Appendicitis Using 2-mSv Computed Tomography: A Secondary Analysis of a Large Pragmatic Randomized Trial – Korean Journal of Radiology

Recent evidence has shown that reduction of abdominal/pelvic CT dose can be reduced to 2 mSv for diagnosing appendicitis without negative ramifications, but widespread use of low dose CT for appendicitis has been slow. This study postulates that one reason low dose CT has not caught on is due to autonomous overnight reads from residents in many academic centers, who may not be experienced with low dose CT. Previous studies however have shown that discrepancy rates between resident and attending reads are less than 3%. This study aims to compare resident’s diagnostic performance and clinical outcomes for appendicitis using 2-mSv (low dose) CT versus conventional-dose CT (CDCT). 107 radiology resident readers participated in the trial via daily practice after online training for low dose CT. The residents’ reports were finalized by attendings and the diagnostic performance of the residents, discrepancies between preliminary and finalized attending reports, and clinical outcomes between the two groups was compared. The authors found that performance and clinical outcomes were not significantly different between the low dose and CDCT groups following radiology residents’ CT readings, indicating that low dose CT can be utilized by radiologists at all levels for suspected appendicits.

Cho J, Kim HY, Lee S, Park JH, Lee KH.   Radiology Residents’ Independent Diagnosis of Appendicitis Using 2-mSv Computed Tomography: A Secondary Analysis of a Large Pragmatic Randomized Trial.   Korean J Radiol. 2023 Jun;24(6):529-540.   https://doi.org/10.3348/kjr.2023.0015

 

 

MRI assessment of rectal cancer response to neoadjuvant therapy: a multireader study – Journal of European Radiology

Due to high morbidity, the question has been raised as to whether some patients with rectal cancer are overtreated with total mesorectal excision (TME). Watching and waiting is an emerging strategy for rectal cancer following neoadjuvant treatment, but selecting appropriate patients remains a challenge. This study aims to measure the accuracy of MRI in assessing rectal cancer response, as prior studies had a small number of radiologists participate and did not report inter-reader variability.  12 radiologists from 8 institutions assessed baseline and restaging MRI scans of 39 patients with rectal cancer. They were asked to assess MRI features and to categorize the overall response to treatment as complete or incomplete. Overall accuracy was 64%, with a sensitivity of 65% for detecting complete response and specificity of 63% for detecting residual tumor. Interpretation of the overall response was more accurate than the interpretation of any individual feature. For most patients’ variability and accuracy were inversely correlated. The authors conclude that based on this data, MRI-based evaluation of response at restaging is insufficiently accurate and has substantial interpretation variability. Some patient’s response to treatment may be easily recognizable on MRI, however this is not the case for most patients.

Yuval, J.B., Patil, S., Gangai, N. et al. MRI assessment of rectal cancer response to neoadjuvant therapy: a multireader study. Eur Radiol 33, 5761–5768 (2023). https://doi.org/10.1007/s00330-023-09480-9

 

 

Ultrasound for necrotizing enterocolitis: how can we optimize imaging and what are the most critical findings? – Pediatric Radiology

Necrotizing enterocolitis (NEC) is a common neonatal condition, especially in premature infants. Diagnosis of NEC has traditionally relied on radiographic findings and clinical presentation; however, ultrasound (US) has gained traction in aiding in management of NEC. Abdominal radiography, considered the gold standard imaging for NEC, may demonstrate fixed, dilated loops of bowel, pneumatosis, free intraperitoneal air, and portal venous gas, but sensitivity is now, commonly resulting in equivocal abdominal radiographs. US has been found to be more sensitive with less inter-reader variability than X-ray. Generally, a high frequency transducer is used along with color doppler for improved identification of mobile bowel gas and peristalsis. Early-stage US findings of NEC include bowel distension, hypervascularity and echogenic mucosa. Later, bowel wall thickening, loss of gut signature and loss of bowel wall distinctness may occur. However, thinning of the bowel wall (<1mm) may indicate a higher risk of perforation for which focal fluid collections, complex ascites or free intraperitoneal gas may be signs. Portal venous gas is sometimes seen as mobile echogenic foci in the main portal vein and branches, or as shadowing echogenic foci in the peripheral liver parenchyma.

The limitations of US are shadowing from bowel gas obscuring deep structures, vibratory motion from ventilators, and decreased bowel perfusion in infants with low cardiac output or vasoconstrictive medications. US findings associated with worse clinical outcomes are pneumoperitoneum, complex focal fluid collections and complex free fluid, while of increased bowel perfusion and anechoic free fluid are low risk findings. The authors conclude that Abdominal US can be a useful adjunct in the assessment of NEC in conjunction with clinical findings and abdominal radiograph findings.

May, L.A., Epelman, M. & Daneman, A. Ultrasound for necrotizing enterocolitis: how can we optimize imaging and what are the most critical findings? Pediatr Radiol 53, 1237–1247 (2023). https://doi.org/10.1007/s00247-022-05545-x

 

 

CT colonography: can we achieve an adequate bowel preparation without diet restriction? – Journal of European Radiology

 

Computed tomography colonography (CTC) is an effective test for colorectal cancer (CRC) in average-risk individuals, with a higher reported participation rate than endoscopic colonoscopy. One of patients most frequent reasons for non-adherence to screening programs is related to bowel prep, so a benefit of CTC is the use of reduced bowel prep. Currently, diet restriction along with bowel prep is standard prior to CTC. This study aims to evaluate if an adequate bowel prep can be achieved without diet restriction, along with reduced amount of cathartic agent and fecal tagging. 1446 outpatients undergoing elective CT colonography were used for the study. These patients had the same bowel prep with reduced cathartic agent the day prior to the exam and a fecal tagging agent the day of the exam, without dietary restrictions.  Adequacy of bowel prep was evaluated using qualitative and quantitative scores. Patients’ compliance was also evaluated with a questionnaire after the end of the exam. The authors found that adequate bowel prep was demonstrated in 93.29% of patients. They also found great patient compliance with the screening test, with 96.5% saying they would be willing to repeat the process in the future.  The authors conclude that lack of diet restriction does not affect CTC quality and favorable patient compliance could potentially increase the participation rate in CRC screening programs.

Rengo, M., Tiberia, F., Vicini, S. et al. CT colonography: can we achieve an adequate bowel preparation without diet restriction? Eur Radiol 33, 5184–5192 (2023). https://doi.org/10.1007/s00330-023-09471-w

 

 

 

Effect of the COVID-19 pandemic on emergency department utilization of computed tomography scans of appendicitis and diverticulitis – Emergency Radiology

Multiple studies have shown a reduced amount of emergency department (ED) visits during the COVID 19 pandemic and lockdown.  The authors assert that it is reasonable to think that during the pandemic people avoided the ED to the point where their condition (such as acute appendicitis [AA] or diverticulitis) progressed to become more serious than during a pre-pandemic context. This study investigates the effect of the COVID-19 lockdown on adult ED visits, abdominal computed tomography (CT) scans, and the presentations of appendicitis and diverticulitis in St. John’s Newfoundland and Labrador (NL). This retrospective analysis compared the numbers of patients presenting to the ED and abdominal CT reports including “appendicitis” and “diverticulitis” during the pre-lockdown, lockdown and post-lockdown timeframes. Daily visits during the lockdown showed a significant decrease in patient volumes compared to pre-lockdown. During lockdown, abdominal CT scans did not drop in proportion to patient volume. The pandemic lockdown had no effect on appendicitis presentations, while diverticulitis presentations likely decreased.  There was no increase in complicated cases of appendicitis or diverticulitis during lockdown. The authors acknowledge that due to multiple factors, the population and infection rates of NL differed significantly from other countries, such as the US, which may limit the generalizability of the study.

Collins, B.W., Robart, A., Lockyer, E.J. et al. Effect of the COVID-19 pandemic on emergency department utilization of computed tomography scans of appendicitis and diverticulitis. Emerg Radiol 30, 297–306 (2023). https://doi.org/10.1007/s10140-023-02125-w

 

 

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