EFSUMB Recommendations for Gastrointestinal Ultrasound Part 3: Endorectal, Endoanal and Perineal Ultrasound

[Imaging in chronic inflammatory bowel disease]

In patients with chronic inflammatory bowel disease (IBD), endoscopic techniques (including capsule techniques and balloon enteroscopy for the small intestine), ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) are primarily used as often complementary imaging techniques. Radiation exposure needs to be kept in mind when using CT and conventional X‑ray-techniques. Therefore, most importantly, ultrasound and MRI have changed the routine diagnostics of intestinal diseases. US, CT and MRI not only assess the lumen but, similarly importantly, also the wall and the surrounding structures of the gastrointestinal tract. Furthermore, functional processes can be visualized and provide important information about passage and perfusion, which is mainly true for real-time ultrasound. CT and MRI are usually carried out with the use of contrast agents as contrast-enhanced CT (CECT) and contrast-enhanced MRI (CEMRI). Ultrasound is performed conventionally or with intravascular (CEUS) and/or extravascular intracavitary contrast agent application (icCEUS). This article provides an overview of the current significance of the mentioned imaging procedures in patients with IBD and discusses the typical indications.

Intersphinktäre Resektion zum Schließmuskelerhalt beim ultratiefen Rektumkarzinom – Ein Update

Die Indikation zum Sphinktererhalt bei Patienten mit einem sehr tief sitzenden Rektumkarzinom ist in vielerlei Hinsicht eine Herausforderung und auch an die Beherrschung der intersphinktären Resektion gebunden. In dieser Arbeit sollen die zunehmend definierten Operationstechniken kurz vorgestellt und aktuell eingeordnet werden.

MRI of early rectal cancer; bisacodyl micro-enema increases submucosal width, reader confidence, and tumor conspicuity

PURPOSE

To investigate the influence of a micro-enema on diagnostic performance, submucosal width, reader confidence, and tumor conspicuity using MRI to stage early rectal cancers (ERC).

METHODS

In this single-center study, we consecutively included 50 participants with assumed ERC who all completed MRI with (MRin) and without (MRex) a micro-enema. The diagnostic performance was recorded for two experienced radiologists using histopathology as the gold standard. In addition, the width of the submucosa in the tumor-bearing wall, reader confidence for T-staging, and tumor conspicuity were assessed. Significance levels were calculated using McNemar's test (diagnostic performance) and Wilcoxon's signed-rank test (reader confidence, submucosal width, and conspicuity). Interreader agreement was assessed using kappa statistics.

RESULTS

Sensitivity/specificity were for Reader1 91%/87% for both MRex and MRin and for Reader2 74%/87% and 89%/87%, both readers p > 0.05. The micro-enema induced a significant widening of the submucosa, p < 0.001, with a mean increase of 2.2/2.8 mm measured by Reader1/Reader2. Reader confidence in T-staging and tumor conspicuity increased for both readers, p < 0.005. The proportion of tumors with both correct staging and high reader confidence increased from 58% (29/50) to 80% (40/50) (p = 0.04) for Reader1 and from 42% (21/50) to 72% (36/50) (p = 0.002) for Reader2. Interreader agreement increased from moderate (kappa 0.58) to good (kappa 0.68).

CONCLUSION

The micro-enema significantly increased the submucosal width in the tumor-bearing wall, reader confidence, and tumor conspicuity and improved interreader agreement from moderate to good. Sensitivity and specificity in T-staging did not improve, but there was a significant increase in the proportion of tumors staged with both high confidence and correct T-stage.

3D Position Tracking Using On-Chip Magnetic Sensing in Image-Guided Navigation Bronchoscopy

This paper presents a compact and low-cost on-chip sensor and readout circuit. The sensor achieves high-resolution 5-degrees-of-freedom (DoF) tracking (x, y, z, yaw, and pitch). With the help of an external wire wound sensor, it can also achieve high-resolution 6-degrees-of-freedom (DoF) tracking (x, y, z, yaw, pitch, and roll angles). The sensor uses low-frequency magnetic fields to detect the position and orientation of instruments, providing a viable alternative to using X-rays in image-guided surgery. To measure the local magnetic field, a highly miniaturised on-chip magnetic sensor capable of sensing the magnetic field has been developed incorporating an on-chip magnetic sensor coil, analog-front end, continuous-time ∆Σ analog-to-digital converter (ADC), LVDS transmitter, bandgap reference, and voltage regulator. The microchip is fabricated using 65 nm CMOS technology and occupies an area of 1.06 mm 2, the smallest reported among similar designs to the best of our knowledge. The 5-DoF system accurately navigates with a precision of 1.1 mm within the volume-of-interest (VOI) of 15 ×15 ×15 cm 3. The 6-DoF system achieves a navigation accuracy of 0.8 mm and an angular error of 1.1 degrees in the same VOI. These results were obtained at a 20 Hz update rate in benchtop characterisation. The prototype sensor demonstrates accurate position tracking in real-life pre-clinical in-vivo settings within the porcine lung of a live swine, achieving a reported worst-case registration accuracy of 5.8 mm.

Contrast-Enhanced Endoscopic Ultrasound Detects Early Therapy Response Following Anti-TNF Therapy in Patients with Ulcerative Colitis

BACKGROUND AND AIMS

Though colonoscopy plays a crucial role in assessing active ulcerative colitis [aUC], its scope is limited to the mucosal surface. Endoscopic ultrasound [EUS] coupled with contrast-enhancement [dCEUS] can precisely quantify bowel wall thickness and microvascular circulation, potentially enabling the quantitative evaluation of inflammation. We conducted a prospective, longitudinal study to assess therapy response using dCEUS in aUC patients undergoing treatment with adalimumab [ADA] or infliximab [IFX].

METHODS

Thirty ADA- and 15 IFX-treated aUC patients were examined at baseline and at 2, 6, and 14 weeks of therapy and 48 weeks of follow-up. Bowel wall thickness [BWT] was measured by EUS in the rectum. Vascularity was quantified by dCEUS using rise time [RT] and time to peak [TTP]. Therapy response was defined after 14 weeks using the Mayo Score.

RESULTS

Patients with aUC displayed a mean BWT of 3.9 ± 0.9 mm. In case of response to ADA/IFX a significant reduction in BWT was observed after 2 weeks [p = 0.04], whereas non-responders displayed no significant changes. The TTP was notably accelerated at baseline and significantly normalized by week 2 in responders [p = 0.001], while non-responders exhibited no significant alterations [p = 0.9]. At week 2, the endoscopic Mayo score did not exhibit any changes, thus failing to predict treatment responses.

CONCLUSION

dCEUS enables the early detection of therapy response in patients with aUC, which serves as a predictive marker for long-term clinical success. Therefore, dCEUS serves as a diagnostic tool for assessing the probability of future therapy success.

Shear-wave elastography predicts T-restaging and pathologic complete response of rectal cancer post neoadjuvant chemoradiotherapy

PURPOSE

To investigate the value of shear-wave elastography (SWE) in assessing the response to neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer.

METHODS

In this study, 455 participants with locally advanced rectal cancer who underwent nCRT at our hospital between September 2021 and December 2022 were prospectively enrolled. The participants were randomly divided into training and test cohorts in a 3:2 ratio. Clinical baseline data, endorectal ultrasound examination data, and SWE measurements were collected for all participants. Logistic regression models were used to predict whether rectal cancer after nCRT had a low T staging (ypT 0-2 stage, Model A) and pathological complete response (pCR) (Model B). Paired Chi-square tests were used to compare the diagnostic performances of the radiologists to those of Models A and B.

RESULTS

In total, 256 participants were included. The area under the receiver operating characteristic curve of Models A and B in the test cohort were 0.94 (0.87, 1.00) and 0.88 (0.80, 0.97), respectively. The optimal diagnostic thresholds for Models A and B were 14.9 kPa for peritumoral mesangial Emean and 15.2 kPa for tumor Emean, respectively. The diagnostic performance of the radiologists was significantly lower than that of Models A and B, respectively (p < 0.05).

CONCLUSION

SWE can be used as a feasible method to evaluate the treatment response of nCRT for locally advanced rectal cancer.

Perianal Fistulizing Crohn's Disease-Associated Anorectal and Fistula Cancers: Systematic Review and Expert Consensus

BACKGROUND & AIMS

Perianal fistulizing Crohn's disease (PFCD)-associated anorectal and fistula cancers are rare but often devastating diagnoses. However, given the low incidence and consequent lack of data and clinical trials in the field, there is little to no guidance on screening and management of these cancers. To inform clinical practice, we developed consensus guidelines on PFCD-associated anorectal and fistula cancers by multidisciplinary experts from the international TOpClass consortium.

METHODS

We conducted a systematic review by standard methodology, using the Newcastle-Ottawa Scale quality assessment tool. We subsequently developed consensus statements using a Delphi consensus approach.

RESULTS

Of 561 articles identified, 110 were eligible, and 76 articles were included. The overall quality of evidence was low. The TOpClass consortium reached consensus on 6 structured statements addressing screening, risk assessment, and management of PFCD-associated anorectal and fistula cancers. Patients with long-standing (>10 years) PFCD should be considered at small but increased risk of developing perianal cancer, including squamous cell carcinoma of the anus and anorectal carcinoma. Risk factors for squamous cell carcinoma of the anus, notably human papilloma virus, should be considered. New, refractory, or progressive perianal symptoms should prompt evaluation for fistula cancer. There was no consensus on timing or frequency of screening in patients with asymptomatic perianal fistula. Multiple modalities may be required for diagnosis, including an examination under anesthesia with biopsy. Multidisciplinary team efforts were deemed central to the management of fistula cancers.

CONCLUSIONS

Inflammatory bowel disease clinicians should be aware of the risk of PFCD-associated anorectal and fistula cancers in all patients with PFCD. The TOpClass consortium consensus statements outlined herein offer guidance in managing this challenging scenario.

Diagnostic Endoscopic Ultrasound (EUS) of the Luminal Gastrointestinal Tract

The purpose of this review is to focus on the diagnostic endoscopic ultrasound of the gastrointestinal tract. In the last decades, EUS has gained a central role in the staging of epithelial and sub-epithelial lesions of the gastrointestinal tract. With the evolution of imaging, the position of EUS in the diagnostic work-up and the staging flow-chart has continuously changed with two extreme positions: some gastroenterologists think that EUS is absolutely indispensable, and some think it is utterly useless. The truth is, as always, somewhere in between the two extremes. Analyzing the most up-to-date and strong evidence, we will try to give EUS the correct position in our daily practice.

Transrectal contrast-enhanced ultrasound-guided transperineal core-needle biopsy versus endoscopic forceps biopsy in the diagnosis of complex rectal lesions

Background

The preoperative pathological diagnosis of rectal lesions is crucial for formulating treatment plans. For subepithelial lesions (SELs) and larger lesions with necrosis of the rectum, endoscopic forceps biopsy (EFB) cannot provide an accurate pathological diagnosis in most cases. By comparing the efficacy and safety of transrectal contrast-enhanced ultrasound-guided transperineal core-needle biopsy (TRCEUS-TP-CNB) and EFB, this study explored the value of TRCEUS-TP-CNB in the diagnosis of complex rectal lesions, such as SELs.

Methods

A retrospective, cross-sectional study was conducted with 32 consecutive patients with complex rectal lesions admitted to our hospital from May 2016 to June 2022. Clinical, ultrasound, and pathological data were collected from these patients who underwent EFB followed by TRCEUS-TP-CNB.

Results

The success rate of EFB was 21.88% (7/32) and that of TRCEUS-TP-CNB was 93.75% (30/32). No significant complications were observed for either biopsy method. Factors affecting the success rate of EFB included the lesion width (cm) (1.90±0.62 vs. 4.26±2.40, P<0.001) and lesion thickness (cm) (1.29±0.51 vs. 2.96±1.75, P<0.001). The success rate of TRCEUS-TP-CNB was not affected by these factors. In the paired study of TRCEUS-TP-CNB and EFB, the times of samples per person (1 vs. 2.14±0.90, P=0.015), number of specimens per sample (8.27±1.93 vs. 3.31±1.67, P<0.001), lesion width (cm) (3.79±2.42 vs. 1.90±0.62, P=0.001), and lesion thickness (cm) (2.64±1.75 vs. 1.29±0.51, P=0.001) were the factors affecting the difference of the sampling success rate. In the SELs, the success rate of EFB was 10% (1/10) and that of TRCEUS-TP-CNB was 100% (10/10), and the difference between the two groups was statistically significant (P=0.004).

Conclusions

TRCEUS-TP-CNB is an effective biopsy method for complex rectal lesions. The success rate of EFB is lower in the larger lesions. Compared with EFB, TRCEUS-TP-CNB required fewer times of samples be taken and obtained more specimens. For larger lesions and SELs of the rectum, TRCEUS-TP-CNB is expected to become one of the preferred biopsy methods.

Perianal Fistula; from Etiology to Treatment - A Review

Anal fistula has been a challenging clinical issue for years due to its complex pathogenesis. The risk of frequent recurrence and incontinence complicates long-term treatment. Recent scientific literature has reviewed new techniques used for anal fistula treatment in recent years, assessing the advantages and disadvantages of each based on clinical outcomes. Although surgery is the main method used to treat anal fistula, there is no simple technique that can completely heal complex anal fistula. The surgical treatment should consider the healing outcome and the protection of anal function comprehensively. Several innovative techniques have emerged in recent years, such as combined techniques based on drainage seton and LIFT-plug, which appear to be relatively effective therapies. However, more multi-center prospective trials with long-term follow-up are needed to validate their effectiveness. In some situations, medical treatment may also be considered.

Convolutional neural network deep learning model accurately detects rectal cancer in endoanal ultrasounds

BACKGROUND

Imaging is vital for assessing rectal cancer, with endoanal ultrasound (EAUS) being highly accurate in large tertiary medical centers. However, EAUS accuracy drops outside such settings, possibly due to varied examiner experience and fewer examinations. This underscores the need for an AI-based system to enhance accuracy in non-specialized centers. This study aimed to develop and validate deep learning (DL) models to differentiate rectal cancer in standard EAUS images.

METHODS

A transfer learning approach with fine-tuned DL architectures was employed, utilizing a dataset of 294 images. The performance of DL models was assessed through a tenfold cross-validation.

RESULTS

The DL diagnostics model exhibited a sensitivity and accuracy of 0.78 each. In the identification phase, the automatic diagnostic platform achieved an area under the curve performance of 0.85 for diagnosing rectal cancer.

CONCLUSIONS

This research demonstrates the potential of DL models in enhancing rectal cancer detection during EAUS, especially in settings with lower examiner experience. The achieved sensitivity and accuracy suggest the viability of incorporating AI support for improved diagnostic outcomes in non-specialized medical centers.

Preoperative assessment of fistula-in-ano using SonoVue enhancement during three-dimensional transperineal ultrasound

Background

Accurate preoperative evaluation of fistula-in-ano can guide the choice of surgical procedure and may improve healing rates. This prospective study aimed to evaluate the accuracy of conventional 3D transperineal ultrasound (3D-TPUS) compared with SonoVue (SVE)-enhanced 3D-TPUS for the detection and classification of anal fistula.

Methods

In this prospective study, 3D-TPUS reconstructions were performed before and after SVE enhancement in 60 patients with fistula-in-ano who intended to undergo surgery at the Department of Anorectal Surgery, Qilu Hospital, Cheeloo College of Medicine, Shandong University (P. R. China) between January 2021 and October 2021. Accuracies of anal fistula classification, complexity classification, detection of anal fistula branches, and detection of internal opening between 3D-TPUS and SVE 3D-TPUS were compared based on a reference standard-intraoperative findings.

Results

This study enrolled 60 patients (mean age, 37.1 ± 11.4 years; mean follow-up, 9 ± 3 months). Intraoperative findings showed that the fistula type was intersphincteric in 23 patients (38.3%), trans-sphincteric in 35 (58.3%; 12 high and 23 low), and suprasphincteric in 2 (3.3%). Moreover, 68 internal openings were found. Compared with the accuracy of 3D-TPUS, that of SVE 3D-TPUS was similar in fistula classification [95.0% (57/60) vs 96.7% (58/60), P = 0.392], but significantly higher in internal opening evaluation [80.9% (55/68) vs 97.1% (66/68), P = 0.001], complexity classification [85.0% (51/60) vs 98.3% (59/60), P = 0.018], and detection of fistula branches [70.4% (19/27) vs 92.6% (25/27), P = 0.031].

Conclusions

SVE 3D-TPUS may be a useful examination for patients with perianal fistulae because of its high accuracy and consistency with intraoperative findings, especially in complex fistula-in-ano and difficult cases.

Value of contrast-enhanced ultrasound in deep angiomyxoma using a biplane transrectal probe: A case report

BACKGROUND

Deep angiomyxoma (DAM) is a very rare tumor type. Magnetic resonance imaging (MRI) is considered the best imaging modality for diagnosing DAM. Computed tomography (CT) is used mainly to assess the invasion range of DAM. The value of ultrasonography in the diagnosis of DAM is still controversial. Through a literature review, we summarized the current state of ultrasonic examination for DAM and reported for the first time the contrast-enhanced ultrasound (CEUS) features of DAM seen using a biplane transrectal probe.

CASE SUMMARY

A 37-year-old woman presented with a sacrococcygeal mass that had gradually increased in size over the previous 6 mo. MRI and CT examinations failed to allow a definite diagnosis to be made. Transperineal core needle biopsy (CNB) guided by transrectal ultrasound and CEUS was suggested after a multidisciplinary discussion. Grayscale ultrasound of the lesion showed a layered appearance with alternating hyperechoic and hypoechoic patterns. Transrectal CEUS showed a laminated distribution of the contrast agent that was consistent with the layered appearance of the tumor on grayscale ultrasound. We performed transperineal CNB of the enhanced area inside the tumor under transrectal CEUS guidance and finally made a definitive diagnosis of DAM through histopathology. The patient underwent laparoscopic-assisted transabdominal surgery combined with transperineal surgery for large pelvic tumor resection and pelvic floor peritoneal reconstruction. No recurrence or metastasis was found at the nine-month follow-up.

CONCLUSION

Transrectal CEUS can show the layered perfusion characteristics of the contrast agent, guiding subsequent transperineal CNB of the enhanced area within the DAM.

Recent advances in the use of ultrasound in Crohn's disease

INTRODUCTION

A clear consensus exists on the role of IUS for the assessment and monitoring of Crohn's disease (CD) in the 'treat-to-target' strategy.

AREAS COVERED

IUS is an accurate tool for the management of CD. It is noninvasive and well tolerated. IUS has good-to-optimal inter-operator reliability either for assessing disease activity or for evaluating treatment response, especially combining Bowel Wall Thickness (BWT) and Color Doppler Signals (CDS). IUS is able to evaluate transmural remission (TR), the ultimate goal of the 'treat-to-target' strategy. Several studies confirmed its accuracy in the assessment of the post-operative recurrence (POR). Thanks to recent advances in trans-perineal ultrasound technique (TPUS), it allows to characterize peri-anal disease and its complications. Small intestine contrast ultrasound (SICUS) and contrast-enhancement ultrasound (CEUS) may improve IUS performance, particularly in stricturing or penetrating CD. Ultrasound elastography (USE) is raising interest for its accuracy in differentiating CD phenotypes (fibrotic versus inflamed).

EXPERT OPINION

IUS is a pivotal step in the management of CD, in early assessment as in therapeutic monitoring, with advantages of evaluating transmural response. Development and validation of novel ultrasound biomarkers of activity and fibrosis, especially those linked to advanced ultrasound techniques, are expected in the coming years.

Basic practices for gastrointestinal ultrasound

The standard diagnostic modalities for gastrointestinal (GI) diseases have long been endoscopy and barium enema. Recently, trans-sectional imaging modalities, such as computed tomography and magnetic resonance imaging, have become increasingly utilized in daily practice. In transabdominal ultrasonography (US), the bowel sometimes interferes with the observation of abdominal organs. Additionally, the thin intestinal walls and internal gas can make structures difficult to identify. However, under optimal US equipment settings, with identification of the sonoanatomy and knowledge of the US findings of GI diseases, US can be used effectively to diagnose GI disorders. Thus, the efficacy of GIUS has been gradually recognized, and GIUS guidelines have been published by the World Federation for Ultrasound in Medicine and Biology and the European Federation of Societies for Ultrasound in Medicine and Biology. Following a systematic scanning method according to the sonoanatomy and precisely estimating the layered wall structures by employing color Doppler make diagnosing disease and evaluating the degree of inflammation possible. This review describes current GIUS practices from an equipment perspective, a procedure for systematic scanning, typical findings of the normal GI tract, and 10 diagnostic items in an attempt to help medical practitioners effectively perform GIUS and promote the use of GIUS globally.

Combined 3D Endoanal Ultrasound and Transperineal Ultrasound Improves the Detection of Anal Sphincter Defects

INTRODUCTION

Anal sphincter injury, mainly due to obstetric or iatrogenic etiology, is the most common cause of fecal incontinence (FI). Three-dimensional endoanal ultrasound (3D EAUS) is used for assessment of the integrity and the degree of anal muscle injury. However, 3D EAUS accuracy may be hampered by regional acoustic effects, such as intravaginal air. Therefore, our aim was to examine whether a combination of transperineal ultrasound (TPUS) and 3D EAUS would improve the accuracy of detection of anal sphincter injury.

METHODS

We prospectively performed 3D EAUS followed by TPUS in every patient evaluated for FI in our clinic between January 2020 and January 2021. The diagnosis of anal muscle defects was assessed in each ultrasound technique by two experienced observers that were blinded to each other's assessments. Interobserver agreement for the results of the 3D EAUS and the TPUS exams was examined. A final diagnosis of anal sphincter defect was based on the results of both ultrasound methods. Discordant results were re-analyzed by the two ultrasonographers for a final consensus on the presence or absence of defects.

RESULTS

A total of 108 patients underwent ultrasonographic assessment due to FI (mean age 69 ± 13). Interobserver agreement for the diagnosis of tear on EAUS and TPUS was high (83%) with Cohen's kappa of 0.62. EAUS confirmed anal muscle defects in 56 patients (52%), while TPUS confirmed them in 62 patients (57%). The final consensus agreed on the diagnosis of 63 (58%) muscular defects and 45 (42%) normal exams. The Cohen's kappa coefficient of agreement between the results of the 3D EAUS and the final consensus was 0.63.

CONCLUSIONS

The combination of 3D EAUS and TPUS improved the detection of anal muscular defects. The application of both techniques for the assessment of the anal integrity should be considered in every patient going through ultrasonographic assessment for anal muscular injury.

Underdiagnosis of internal anal sphincter trauma following vaginal delivery

OBJECTIVE

Damage to the anal sphincter during childbirth remains the leading cause of fecal incontinence in women. Defects in the internal (IAS) or external anal sphincter, alongside symptoms and sphincter tone, will generally dictate the suggested mode of delivery in any successive pregnancy. This study aimed to examine using endoanal ultrasonography the prevalence of IAS damage in women referred with Grade-3a or -3b obstetric anal sphincter injury (OASI) in a tertiary-referral perineal clinic.

METHODS

This was a retrospective observational study of all women referred to a tertiary-referral perineal clinic after primary repair of OASI (Grade 3a-c, 4) diagnosed for the first time following vaginal delivery between January 2016 and December 2019, inclusive. Women were assessed using the Wexner bowel continence questionnaire, digital examination of sphincter tone and endoanal ultrasound. Injuries in each sphincter were classified as a scar (≤ 30°) or defect (> 30-90° or > 90°) on endoanal imaging in the axial plane.

RESULTS

In total, 615 women were referred following primary repair of OASI. Sonographic evidence of damage to the IAS was seen in 9.1% (46/506) of women diagnosed with a Grade-3a/3b injury. In women referred with a Grade-3a/3b tear, symptom scores were statistically higher (P = 0.025) in those with an IAS defect > 30° compared to those with an intact or scarred IAS, although the median score was zero in both groups. The proportion of women in each group with severe symptoms (score > 9) was similar (2.6% vs 6.5%; P = 0.148). Among women referred with a Grade-3a/3b tear, sphincter tone was reduced more frequently in those with a defect of the IAS than in those with an intact or scarred IAS (52.2% vs 11.7%; odds ratio, 8.14 (95% CI, 4.26-15.67); P < 0.001). Regardless of the reason for referral, women with reduced sphincter tone on rectal examination were four times as likely to have had an IAS defect > 30° than were those with normal resting tone (risk ratio, 4.58 (95% CI, 3.25-6.45); P < 0.001).

CONCLUSIONS

One in 11 women diagnosed with a Grade-3a or -3b tear have evidence of damage to their IAS on endoanal ultrasound. Damage to this muscle is linked to fecal incontinence in women and can have a significant impact on the planning of any future deliveries. This study highlights the importance of established perineal clinics with access to ultrasound. Nonetheless, if reduced sphincter tone is felt on rectal examination, a clinician should have a high index of suspicion for an occult IAS injury. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Diagnostic performance of endorectal ultrasound combined with shear wave elastography for rectal tumors staging

OBJECTIVE

This study aims to analyze the performance of endorectal ultrasound (ERUS) combined with shear wave elastography (SWE) for rectal tumor staging.

METHODS

Forty patients with rectal tumors who had surgery were enrolled. They underwent ERUS and SWE examinations before surgery. Pathological results were used as the gold standard for tumor staging. The stiffness values of the rectal tumor, peritumoral fat, distal normal intestinal wall, and distal perirectal fat were analyzed. The diagnostic accuracy of ERUS stage, tumor SWE stage, ERUS combined with tumor SWE stage, and ERUS combined with peritumoral fat SWE stage were compared and evaluated by receiver operating characteristic (ROC) curve to select the best staging index.

RESULTS

From T1 to T3 stage, the maximum elasticity (Emax) of the rectal tumor increased gradually (p < 0.05). The cut-off values of adenoma/T1 and T2, T2 and T3 tumors were 36.75 and 85.15kPa, respectively. The diagnostic coincidence rate of tumor SWE stage was higher than that of ERUS stage. Overall diagnostic accuracy of ERUS combined with peritumoral fat SWE Emax restaging was significantly higher than that of ERUS.

CONCLUSIONS

ERUS combined with peritumoral fat SWE Emax for tumor restaging can effectively distinguish between stage T2 and T3 rectal tumors, which provides an effective imaging basis for clinical decisions.

Point-of-care Ultrasound of the Gastrointestinal Tract

The widespread use of portable ultrasound scanners has promoted the concept of point of care ultrasound (POCUS), namely "ultrasound performed bedside and interpreted directly by the clinician." The purpose of this short review is to outline how POCUS can be used in patients with diseases of the gastrointestinal (GI) tract. POCUS is not a replacement for comprehensive ultrasound, but rather allows physicians immediate access to clinical imaging for rapid diagnosis and efficient work-up and treatment of the patients. There are many indications for doing POCUS of the GI tract, including abdominal pain, diarrhea, palpable masses, and to detect fluid or free air in the abdominal cavity. To improve the visibility of deeper parts of the abdomen, the graded compression technique with the scan head is useful. During POCUS, the operator should look for signs of severe pathology including target lesions, the pseudo-kidney sign, the onion sign, dilated bowel loops, gastric retention, free fluid, and free air, depending on the actual clinical problem. We conclude that POCUS of the GI tract is very useful to provide a rapid diagnosis in many clinical scenarios.

Role of transperineal ultrasound in evaluation of patients with perianal inflammatory disorders

Background

The aim of this study was to study the degree of accuracy of transperineal ultrasound (TPUS) in pre-operative evaluation and follow-up of cases with perianal inflammatory disorders in relation to MRI findings. Thirty patients with symptoms and signs of perianal inflammatory disorders underwent TPUS and pelvic MRI examinations. The radiologist who performed the TPUS was blinded to MR findings and was asked to comment on the site of the internal opening and extension of the tract, any related side branches or collections.

Results

The overall accuracy of TPUS in detection of the site of internal opening of perianal tracts was 83.33%, with sensitivity of 91.30%. TPUS showed sensitivity, specificity and accuracy of 100% in detection of horseshoe collections. The overall accuracy of TPUS in detection of perianal abscesses was 93.33% with specificity of 100%. TPUS showed sensitivity of 50.00%, specificity of 92.31% and accuracy of 86.67% in visualization of side branches. TPUS showed sensitivity of 33.33%, specificity of 88.89% and overall accuracy of 83.33% in detection of supralevator extension of perianal tracts. TPUS correctly classified (23/30) perianal tracts with accuracy of 76.7%.

Conclusions

TPUS can be used as a first diagnostic tool in patients with perianal inflammatory disorders and related pathologies, particularly horseshoe collections which can change the operative decision made by the surgeon. TPUS can be used in repeated follow-up during the course of management of perianal inflammatory disorders or when other imaging modalities are unavailable or contra-indicated.

Endorectal Ultrasound Shear-Wave Elastography of Complex Rectal Adenoma and Early Rectal Cancer

Purpose: To investigate the diagnostic performance of endorectal ultrasound (ERUS), shear-wave elastography (SWE), and magnetic resonance imaging (MRI) in patients with a complex rectal adenoma or an early rectal cancer, i.e., T1 or T2 adenocarcinoma in a clinical setting, and to evaluate the association between SWE and stromal fraction (SF) and apparent diffusion coefficient (ADC) and SF. Method: This prospective study included patients undergoing ERUS and SWE for a rectal tumor subsequently confirmed by histopathology to be an adenoma or a T1 or T2 adenocarcinoma. The accuracy of the imaging methods was assessed by comparing the T category as determined by ERUS and MRI with histopathology, which served as the gold standard. SF was assessed on surgical specimens. Results: A total of 86 patients were included. Of these, 62 patients had adenomas and 24 patients had carcinomas, of which 11 were T1 tumors and 13 were T2 tumors. ERUS and MRI yielded sensitivity, specificity, and accuracy of 0.79 and 0.73, 0.95 and 0.90, and 0.86 and 0.78, respectively, for discrimination between benign and malignant lesions. The area under the receiver operating characteristics curve for SWE was 0.88, and with a cut-off value of 40 kPa the sensitivity, specificity, and accuracy were 0.79, 0.89, and 0.86, respectively. There was a positive correlation between SF and SWE with a p-value of <0.001 and a negative correlation between SF and ADC with a p-value of 0.011. Conclusion: Both ERUS and MRI classified T categories with a high accuracy; however, ERUS classified more adenomas correctly than MRI. In this small population, SWE could differentiate an adenoma from early carcinoma. SF was correlated with both SWE and ADC, as increasing SF tended to yield higher SWE and lower ADC values.

Anal Cancer: Emerging Standards in a Rare Rare Disease

The social stigma surrounding an anal cancer diagnosis has traditionally prevented open discussions about this disease. However, as recent treatment options and an increasing rate of diagnoses are made worldwide, awareness is growing. In the United States alone, 9,090 individuals were expected to be diagnosed with anal cancer in 2021. The US annual incidence of squamous cell carcinoma of the anus continues to increase by 2.7% yearly, whereas the mortality rate increases by 3.1%. The main risk factor for anal cancer is a human papillomavirus infection; those with chronic immunosuppression are also at risk. Patients with HIV are 19 times more likely to develop anal cancer compared with the general population. In this review, we have provided an overview of the carcinoma of the anal canal, the role of screening, advancements in radiation therapy, and current trials investigating acute and chronic treatment-related toxicities. This article is a comprehensive approach to presenting the existing data in an effort to encourage continuous international interest in anal cancer.

Intra- and Interobserver Variability of Shear Wave Elastography in Rectal Cancer

Simple Summary

For a diagnostic tool to be important, there must be a high level of agreement between different observers. If not, the reliability of the measurement can not be considered valid. Previous studies have evaluated the reproducibility of tissue stiffness measurements of rectal tumors, but only on previously obtained images. Therefore, we aimed to investigate the issue in a clinical setting and found a high level of agreement between observers.

Abstract

Background: Endorectal ultrasound (ERUS) is an important tool when evaluating complex rectal adenomas and rectal cancer, and the accuracy is improved by adding elastography measurements. A high interobserver agreement is imperative in clinical practice. Therefore, the aim of this study was to evaluate interobserver agreement assessed on real-time images. Additionally, we investigated the intra- and interobserver agreement between experienced and inexperienced observers. Materials and methods: We prospectively included patients referred to an ERUS at the Department of Radiology with a complex rectal polyp or suspected rectal malignancy. Two operators independently scanned each patient in turn. Furthermore, four observers assessed previously obtained images using three different methods for placing the region of interest (ROI). Three months later, the four observers reassessed the images to assess intraobserver variability. Results: A total of 19 patients were included for live assessment. Agreement of tumor classification was substantial for T stage (kappa: 0.86) and fair for N stage (kappa: 0.73), with an absolute agreement for T and N stages of 84% and 89%, respectively. Agreement of SWE was good for Emean (ICC 0.94, 95% CI 0.86–0.98) and fair for Emax (ICC 0.85, 95% CI 0.66–0.94). Intra- and interobserver agreement between inexperienced and experienced observers showed good to excellent agreement with all ROI methods. Conclusion: Interobserver agreement is high in SWE when performed in a clinical setting. We found the best agreement using the mean value of several ROIs. Intra- and interobserver agreement was high regardless of operator experience.

Perianal Imaging in Crohn Disease: Current Status With a Focus on MRI, From the AJR Special Series on Imaging of Inflammation

Fistulizing perianal disease, a frequent, chronic, and often debilitating manifestation of Crohn disease (CD) in adults and children, has been relatively refractory to treatment in the past. The advent of biologic agents such as anti-tumor necrosis factor-α and cellular therapies, used in conjunction with a range of surgical interventions, has greatly improved disease outcomes, although complete remission can still be elusive. This Special Series review considers current perianal imaging options, specifically pelvic MRI and endoanal and transperineal ultrasound, as well as their roles in the diagnosis, management, and assessment of treatment response. Pelvic MRI is the first-line modality for imaging perianal CD, given the complexity of fistulas encountered in CD. MRI technical acquisition parameters for adults and children and an approach to MRI interpretation and reporting are provided. Anatomic classification systems for fistulizing peri-anal disease are presented. We also explore the history, current landscape, and future developments of MRI features of perianal disease as imaging biomarkers, to quantify activity and severity and to consider CD MRI-based inflammatory activity scores. We discuss the reliability and validation of a number of indexes (including the pediatric MRI-based perianal CD [PEMPAC] index, the MR novel index for fistula imaging in CD [MAGNIFI-CD], the Van Assche index, and the modified Van Assche index), their potential to quantify treatment response, and possible prognostic capabilities.

Ultrasonography in inflammatory bowel disease - So far we are?

Intestinal ultrasound (IUS) is a non‐invasive and accurate tool to assess inflammatory bowel disease. The ECCO‐ESGAR guideline recommends the use of IUS for the assessment of disease activity and complications in Crohn's disease (CD). In addition, an increasing body of evidence suggests the use of IUS as alternative to colonoscopy in monitoring CD and in assessing disease activity of ulcerative colitis. Early responsiveness of IUS findings by the first weeks of treatment and the advantage to perform the procedure in real time may dramatically change frequency of the assessment of treatment response in the future and speed up the clinical decision‐making process. Development of validated and reproducible sonographic scores to measure disease activity and therapeutic response and spread of knowledge of IUS remain relevant issues for the future in which current researchers and the International Bowel Ultrasound (IBUS) Group are actively engaged.

Highlights of the development in ultrasound during the last 70 years: A historical review

This review looks at highlights of the development in ultrasound, ranging from interventional ultrasound and Doppler to the newest techniques like contrast-enhanced ultrasound and elastography, and gives reference to some of the valuable articles in Acta Radiologica. Ultrasound equipment is now available in any size and for any purpose, ranging from handheld devices to high-end devices, and the scientific societies include ultrasound professionals of all disciplines publishing guidelines and recommendations. Interventional ultrasound is expanding the field of use of ultrasound-guided interventions into nearly all specialties of medicine, from ultrasound guidance in minimally invasive robotic procedures to simple ultrasound-guided punctures performed by general practitioners. Each medical specialty is urged to define minimum requirements for equipment, education, training, and maintenance of skills, also for medical students. The clinical application of contrast-enhanced ultrasound and elastography is a topic often seen in current research settings.

Can Ultrasound Elastography Discriminate between Rectal Adenoma and Cancer? A Systematic Review

BACKGROUND

Rectal cancer is a common malignancy. Since the introduction of bowel-screening programs, the number of patients with advanced adenomas and early rectal cancer has increased. Despite improved diagnostics, the discrimination between rectal adenomas and early rectal cancer (i.e., pT1-T2) remains challenging. The purpose of this systematic review was to evaluate the diagnostic performance of endorectal ultrasound (ERUS) elastography in discriminating rectal adenomas from cancer.

METHOD

Using PRISMA guidelines, a systematic search was performed on PubMed, Embase, and MEDLINE databases. Studies evaluating the primary staging of rectal adenomas and cancer using ERUS elastography were included.

RESULTS

Six studies were identified; three evaluated the discrimination between adenomas and cancer; two evaluated adenomas and early rectal cancer (i.e., pT1-T2); one evaluated performance on different T categories. All studies reported increased diagnostic accuracy of ERUS elastography compared to ERUS. Sensitivity, specificity and accuracy ranged 0.93-1.00, 0.83-1.00 and 0.91-1.00, respectively, when discriminating adenomas from cancer. In the differentiation between adenomas and early rectal cancer, the sensitivity, specificity and accuracy were 0.82-1.00, 0.86-1.00 and 0.84-1.00, respectively.

CONCLUSION

Elastography increases the accuracy of ERUS and may provide valuable information on malignant transformation of rectal lesions.

Bowel Ultrasound in Inflammatory Bowel Disease: How Far in the Grayscale?

Bowel ultrasound (BUS) is a non-invasive and accurate technique for assessing activity, extension of disease, and complications in inflammatory bowel diseases. The main advantages of BUS are its safety, reproducibility, and low costs. Ancillary technologies of BUS (i.e., color Doppler and wave elastography) could broaden the diagnostic power of BUS, allowing one to distinguish between inflammation and fibrosis. Considering the costs and invasiveness of colonoscopy and magnetic resonance, BUS appears as a fast, safe, and accurate technique. The objective measures of disease allow one to make clinical decisions, such as optimization, switch, or swap of therapy. Previous studies reported a sensitivity and a specificity of more than 90% compared to endoscopy and magnetic resonance. Lastly, transperineal ultrasound (TPUS) is a promising approach for the evaluation of perianal disease in Crohn’s disease (CD) and disease activity in patients with ulcerative proctitis or pouchitis. Bowel ultrasound is being incorporated in the algorithm of managing inflammatory bowel diseases. Transmural healing evaluated through ultrasonography is emerging as a complementary target for disease treatment. In this review, we aimed to summarize and discuss the current evidence on BUS in the management of inflammatory bowel diseases and to address the challenges of a full validation of this technique.

Gastrointestinal Ultrasound in Functional Disorders of the Gastrointestinal Tract - EFSUMB Consensus Statement

Abdominal ultrasonography and intestinal ultrasonography are widely used as first diagnostic tools for investigating patients with abdominal symptoms, mainly for excluding organic diseases. However, gastrointestinal ultrasound (GIUS), as a real-time diagnostic imaging method, can also provide information on motility, flow, perfusion, peristalsis, and organ filling and emptying, with high temporal and spatial resolution. Thanks to its noninvasiveness and high repeatability, GIUS can investigate functional gastrointestinal processes and functional gastrointestinal diseases (FGID) by studying their behavior over time and their response to therapy and providing insight into their pathophysiologic mechanisms. The European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) has established a Task Force Group consisting of GIUS experts, which developed clinical recommendations and guidelines on the role of GIUS in several acute and chronic gastrointestinal diseases. This review is dedicated to the role of GIUS in assisting the diagnosis of FGID and particularly in investigating patients with symptoms of functional disorders, such as dysphagia, reflux disorders, dyspepsia, abdominal pain, bloating, and altered bowel habits. The available scientific evidence of GIUS in detecting, assessing, and investigating FGID are reported here, while highlighting sonographic findings and its usefulness in a clinical setting, defining the actual and potential role of GIUS in the management of patients, and providing information regarding future applications and research.

Assessing Rectal Cancer Treatment Response Using Coregistered Endorectal Photoacoustic and US Imaging Paired with Deep Learning

Background Conventional radiologic modalities perform poorly in the radiated rectum and are often unable to differentiate residual cancer from treatment scarring. Purpose To report the development and initial patient study of an imaging system comprising an endorectal coregistered photoacoustic (PA) microscopy (PAM) and US system paired with a convolution neural network (CNN) to assess the rectal cancer treatment response. Materials and Methods In this prospective study (ClinicalTrials.gov identifier NCT04339374), participants completed radiation and chemotherapy from September 2019 to September 2020 and images were obtained with the PAM/US system prior to surgery. Another group's colorectal specimens were studied ex vivo. The PAM/US system consisted of an endorectal imaging probe, a 1064-nm laser, and one US ring transducer. The PAM CNN and US CNN models were trained and validated to distinguish normal from malignant colorectal tissue using ex vivo and in vivo patient data. The PAM CNN and US CNN were then tested using additional in vivo patient data that had not been seen by the CNNs during training and validation. Results Twenty-two patients' ex vivo specimens and five patients' in vivo images (a total of 2693 US regions of interest [ROIs] and 2208 PA ROIs) were used for CNN training and validation. Data from five additional patients were used for testing. A total of 32 participants (mean age, 60 years; range, 35-89 years) were evaluated. Unique PAM imaging markers of the complete tumor response were found, specifically including recovery of normal submucosal vascular architecture within the treated tumor bed. The PAM CNN model captured this recovery process and correctly differentiated these changes from the residual tumor. The imaging system remained highly capable of differentiating tumor from normal tissue, achieving an area under the receiver operating characteristic curve of 0.98 (95% CI: 0.98, 0.99) for data from five participants. By comparison, the US CNN had an area under the receiver operating characteristic curve of 0.71 (95% CI: 0.70, 0.73). Conclusion An endorectal coregistered photoacoustic microscopy/US system paired with a convolutional neural network model showed high diagnostic performance in assessing the rectal cancer treatment response and demonstrated potential for optimizing posttreatment management. © RSNA, 2021 Supplemental material is available for this article. See also the editorial by Klibanov in this issue.

Transperineal core-needle biopsy of a rectal subepithelial lesion guided by endorectal ultrasound after contrast-enhanced ultrasound: A case report

BACKGROUND

Rectal subepithelial lesions (SELs) are commonly seen in endoscopic examination, generally manifested as bumps with a smooth surface. Precise preoperative diagnoses for rectal SELs are difficult because abnormal tissues are not easily to be obtained by regular endoscopic forceps biopsy. Traditional guidance modalities of preoperative biopsy, including endoscopic ultrasound, computed tomography, and transabdominal ultrasound, are often unsatisfactory. An updated, safe, and effective biopsy guidance method is required. We herein report a new biopsy guidance modality—endorectal ultrasound (ERUS) combined with contrast-enhanced ultrasound (CEUS).

CASE SUMMARY

A 32-year-old woman complained of a mass inside the rectovaginal space for 9 years, which became enlarged within 1 year. A rectal SEL detected by endoscopy was suspected to be a gastrointestinal stromal tumor or exophytic uterine fibroid. Pathological diagnosis was difficult because of unsuccessful transabdominal core needle biopsy with insufficient tissues, as well as vaginal hemorrhage. A second biopsy was suggested after multiple disciplinary treatment discussion, which referred to a transperineal core needle biopsy (CNB) guided by ERUS combined with CEUS. Adequate samples were procured and rectal gastrointestinal stromal tumor was proved to be the pathological diagnosis. Imatinib was recommended for first-line therapy by multiple disciplinary treatment discussion. After the tumor shrunk, resection of the rectal gastrointestinal stromal tumor was performed through the posterior vaginal wall. Adjuvant therapy was applied and no recurrence or metastasis has been found by the last follow-up on December 13, 2019.

CONCLUSION

Transperineal CNB guided by ERUS and CEUS is a safe and effective preoperative biopsy of rectal SELs yet with some limitations.

Clinical Awareness and Acceptance of Sonographically Diagnosed Epiploic Appendagitis (EA): A Retrospective Analysis of EA in a Single Tertiary Academic Referral Center

Purpose To describe the clinical awareness and acceptance of ultrasound-diagnosed acute epiploic appendagitis (EA) and their importance to avoid unnecessary therapeutic and imaging measures.

Patients and Methods The data were obtained of n=54 patients with acute, localized, peritonitic pain and EA diagnosed by B-mode ultrasound and contrast-enhanced ultrasound examination from November 2003 to September 2020. All examinations were performed by a German Society for Ultrasound in Medicine (DEGUM) Level III qualified examiner. Based on documentation by the treating physicians, the clinical awareness and acceptance of EA diagnosis was determined in all patients and compared between subgroups diagnosed before 2013 and from 2013 onwards. In 2013, a local educational training program regarding the diagnosis of and therapy for EA was initiated for physicians.

Results In all patients, EA was sonographically diagnosed by a DEGUM level III qualified examiner. At enrollment, EA was mentioned as a suspected clinical diagnosis in n=1/54 (1.9%) patient. Furthermore, in n=39/54 (72.2%) cases, the EA was documented and accepted by the treating physicians at the time of patient discharge as the final clinical diagnosis. The clinical acceptance was significantly higher from 2013 onwards compared with before 2013 (p<0.05). Moreover, in n=26/54 (48.1%) patients, unnecessary therapeutic measures were initiated, with no significant difference between pre-2013 and post-2013 numbers (p>0.05).

Conclusion In our retrospective study, we showed that awareness and acceptance of the disease EA are low. Low diagnostic acceptance of EA by the clinician leads to unnecessary therapeutic and imaging measures and is a general problem related to rare diseases in the healthcare system.

Evaluation of the Extent of Mesorectal Invasion and Mesorectal Fascia Involvement in Patients with T3 Rectal Cancer With 2-D and 3-D Transrectal Ultrasound: A Pilot Comparison Study With Magnetic Resonance Imaging Findings

The aim of this study was to determine the value of 2-D and 3-D transrectal ultrasound (TRUS) in assessing the extent of mesorectal invasion (EMI) and mesorectal fascia involvement (MRF+) in patients with T3 rectal tumours. We retrospectively evaluated 80 patients with T3 stage rectal cancer who were pre-operatively evaluated by 2-D and 3-D TRUS before neoadjuvant chemoradiotherapy by using magnetic resonance imaging (MRI) as a reference standard. The T3 stage was subdivided into T3 ab (EMI ≤5 mm) and T3 cd (EMI >5 mm). The consistency assessment of the T3 sub-staging and MRF+ was compared between 2-D and 3-D TRUS using Cohen's kappa statistic. The concordance of the T3 sub-staging based on EMI was excellent between the 3-D TRUS and MRI (κ = 0.84) and good between the 2-D TRUS and MRI (κ = 0.67). For the assessment of MRF+ (κ = 0.82), 3-D TRUS and MRI showed excellent concordance. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 3-D TRUS for MRF+ assessment was 95.3%, 86.5%, 89.1% and 94.1%, respectively. The agreement between 3-D TRUS and MRI for the assessment of T3 sub-staging and MRF status was better in low rectal cancer (both κ = 0.85) than in middle (κ = 0.79 and 0.77) rectal cancer. Compared with MRI, 3-D TRUS has more advantages in the sub-staging of T3 rectal cancer and the assessment of MRF+ than those of 2-D TRUS, especially in low rectal cancer. For patients with T3 rectal cancer, 3-D TRUS may well complement MRI for selecting the appropriate treatment.

COMPARATIVE EVALUATION OF MULTIPARAMETRIC ENDORECTAL ULTRASOUND AND ENHANCED IMAGING COLONOSCOPY IN THE DIAGNOSIS OF EARLY COLORECTAL CANCER

AIM: to compare multiparametric endorectal ultrasound (ERUS) and enhanced imaging colonoscopy in the diagnosis of early colorectal cancer.

PATIENTS AND METHODS: the study included 78 patients with epithelial rectal tumor. All the patients underwent multiparametric ERUS and colonoscopy with examination by narrow beam imaging (NBI) at optical magnification. All the patients were operated.

RESULTS: a morphological examination removed specimens revealed adenomas in 48 cases, in 19 specimens – adenocarcinomas in situ and T1, and in 11 specimens – adenocarcinomas with invasion of the muscle layer or deeper. When calculating the accuracy indicators of diagnostic methods for groups of patients with adenoma, Tis-T1 adenocarcinoma, and T2-T3 adenocarcinoma, the difference in the sensitivity and specificity of the methods in none of the presented groups did not reach the level of statistical significance (p>0.05).ROC analysis showed that ultrasound has a prognostic value comparable to colonoscopy. The area difference was 0.013 (p=0.85).

CONCLUSION: endoscopy and ultrasound have similar value in the diagnosis of malignant transformation of rectal adenomas.

Sonographic assessment of infectious diseases of the gastrointestinal tract: from scanning to diagnosis

BACKGROUND

Sonography of the gastrointestinal (GI) tract is a practical, safe, inexpensive, and reproducible diagnostic tool for the evaluation, diagnosis, and follow-up of infectious bowel disease. The modality is rapidly gaining prominence among clinicians on a global scale. In the United States, however, ultrasound of the bowel remains underutilized primarily due to insufficient experience among radiologists and sonographers in performing sonographic bowel assessment. This lack of experience and knowledge results in misinterpretations, missed diagnoses, and underutilization of this modality in patients with acute abdomen, with the majority of GI pathology on sonography discovered incidentally.

OBJECTIVES

This article aims to demonstrate the characteristic sonographic findings associated with GI infectious processes as well as provide dedicated ultrasound protocols for evaluation of the GI tract.

CONCLUSION

This article serves a twofold purpose, raising awareness of the utility of this imaging modality within the radiology community and also providing practical teaching points for sonographic evaluation of infectious disorders of the GI tract.

Transperineal ultrasound for assessment of fistulas and abscesses: a pictorial essay

Perianal fistulas and abscesses may be cryptogenetic or associated with inflammatory bowel disease (IBD), specifically Crohn's disease. Proper identification and classification of these lesions are paramount for correct therapeutic management. Current diagnostic modalities include MRI (magnetic resonance imaging), EUS (endoscopic ultrasound), EUA (exam under anaesthesia) and recently, transperineal ultrasound (TPUS). The latter has been proposed as a noninvasive, easily available and cost-effective technique to diagnose, assess and follow up perianal disease particularly in IBD patients. This pictorial review focuses on the role of TPUS in clinical practice, highlighting the features of fistulas and abscesses.