Comparative effectiveness of imaging modalities for preoperative assessment of anorectal malformation in the pediatric population

The comparison of magnetic resonance and fluoroscopic imaging options in the preoperative assessment of boys with anorectal malformations and a colostomy

BACKGROUND

In recent decades, magnetic resonance imaging (MRI) has gained prominence as a standard diagnostic method for preoperative assessment in patients with anorectal malformations and a colostomy, with the potential to replace the classic fluoroscopic distal pressure colostogram (FDPC). Three MRI techniques are available: MRI-distal pressure colostogram with gadolinium (MRI-DPCG) or saline (MRI-DPCS) instillation into the colostomy and native MRI without colostomy instillation.

OBJECTIVE

To evaluate and compare the diagnostic accuracy of MRI (native MRI, MRI-DPCG and MRI-DPCS) in the preoperative workup of boys with an anorectal malformation and a colostomy and to compare it to FDPC.

MATERIALS AND METHODS

Sixty-two boys with preoperative MRI using one of the three approaches and 43 with FDPC met the inclusion criteria for this retrospective study. The presence and localization of rectal fistulas according to the Krickenbeck classification were evaluated and compared with intraoperative findings.

RESULTS

The accuracy of fistula detection for MRI in general (regardless of the technique), MRI-DPCS, MRI-DPCG, native MRI and FDPC was 95% (59/62, P<0.001), 100% (12/12, P=0.03), 100% (30/30, P<0.001), 85% (17/20, P=0.41) and 72% (31/43, P=0.82), respectively. The accuracy of describing fistula type in patients with a correctly detected fistula using these methods was 96% (45/47, P<0.001), 100% (9/9, P<0.001), 100% (23/23, P<0.001), 87% (13/15, P<0.001) and 67% (13/21, P=0.002), respectively.

CONCLUSION

MRI is a reliable method for detecting and classifying fistulas in boys with an anorectal malformation and a colostomy and can be considered the modality of first choice for preoperative workup.

Preoperative fistula diagnostics in male anorectal malformations after colostomy: a single-center experience

BACKGROUND

Accurate preoperative fistula diagnostics in male anorectal malformations (ARM) after colostomy are of great significance. We reviewed our institutional experiences and explored methods for improving the preoperative diagnostic accuracy of fistulas in males with ARMs after colostomy.

METHODS

A retrospective analysis was performed on males with ARMs after colostomy admitted to our hospital from January 2015 to June 2022. All patients underwent magnetic resonance imaging (MRI) and high-pressure colostogram (HPC) before anorectal reconstruction. Patients with no fistula as diagnosed by both modalities underwent a voiding cystourethrogram (VCUG). General information, imaging results and surgical results were recorded.

RESULTS

Sixty-nine males with ARMs after colostomy were included. Age at the time of examination was 52 ~ 213 days, and the median age was 89 days. The Krickenbeck classification according to surgical results included rectovesical fistula (n = 19), rectoprostatic fistula (n = 24), rectobulbar fistula (n = 19) and no fistula (n = 7). There was no significant difference in the diagnostic accuracy between MRI and HPC for different types of ARMs. For determining the location of the fistula, compared to surgery, HPC (76.8%, 53/69) performed significantly better than MRI (60.9%, 42/69) (p = 0.043). Sixteen patients diagnosed as having no fistula by MRI or HPC underwent a VCUG, and in 14 patients, the results were comfirmed. However, there were 2 cases of rectoprostatic fistula that were not correctly diagnosed.

CONCLUSION

High-pressure colostogram has greater accuracy than MRI in the diagnosis of fistula type in males with ARMs after colostomy. For patients diagnosed with no fistula by both methods, VCUG reduces the risk of false-negative exclusion, and rectoprostatic fistula should be considered during the operation.

Levator ani asymmetry and deviation in high-type anorectal malformation evaluated by magnetic resonance imaging

INTRODUCTION

The levator ani (LA) complex in high-type imperforate anus (H-IA), low-type imperforate anus (L-IA), and Hirschsprung's disease (HD) patients as controls were documented using magnetic resonance imaging (MRI) and compared for symmetry.

MATERIALS AND METHODS

Mean left:right LA thickness ratio (LA ratio), and deviation of the LA from the pubococcygeal line (PCL; LA angle) were calculated from thin-slice MRI images (axial 2 mm, coronal 2 mm, and sagittal 3 mm) of the puborectalis and pubococcygeus taken parallel to the PCL under sedation in H-IA (n=14), L-IA (n=16), and HD (n=9).

RESULTS

MRI scans were performed between January 2018 and June 2021. LA were significantly thinner in H-IA (1.78±0.46 mm) compared with L-IA (2.97±0.55 mm) and controls (2.87±0.32 mm), p<0.0001. LA ratio was significantly lower in H-IA (0.71±0.15) compared with L-IA (0.93±0.04), and controls (0.91±0.06), p<0.0001. Mean LA-angle was significantly different in H-IA, 10.8° (range 6°-19°), versus L-IA and controls, both zero degrees (range 0°-5°), p<0.0001, respectively.

CONCLUSIONS

LA was confirmed to be significantly asymmetric in H-IA. Because outcome of surgical repair involving a midline incision, such as posterior sagittal anorectoplasty could be impaired, pediatric surgeons are advised to plan surgical intervention for H-IA carefully and appropriately.

Imaging of anorectal malformations: where are we now? Abdominal imaging task force of the European Society of Paediatric Radiology

Anorectal and cloacal malformations are a broad mix of congenital abnormalities related to the distal rectum and anus. Confusion exists between all the forms in this large and heterogeneous group. The spectrum includes everything from anal stenosis, ventral anus, anal atresia (with and without fistula) and the full spectrum of cloacal malformations. Imaging in these conditions is done through the whole armamentarium of radiologic modalities, with very different imaging strategies seen across the centres where these conditions are managed. In 2017, the European Society of Paediatric Radiology (ESPR) abdominal imaging task force issued recommendations on the imaging algorithm and standards for imaging anorectal malformations. This was followed by further letters and clarifications together with an active multispecialty session on the different imaging modalities for anorectal malformations at the 2018 ESPR meeting in Berlin. Through this paper, the abdominal task force updates its guidelines and recommended imaging algorithm for anorectal malformations.

Assessment of sacral ratio in patients with anorectal malformations: Can magnetic resonance imaging replace conventional radiograph?

INTRODUCTION

In patients with anorectal malformations (ARM), the sacral ratio (SR) serves as an established predictive marker for functional prognosis and is derived from conventional radiographs. More recently, magnetic resonance imaging (MRI) has emerged as a diagnostic alternative for preoperative/baseline assessment of patients with ARM. With this study we aimed to evaluate if the SR could be reliable be measured from MRI images and if it correlated to SR measurements obtained from radiographs.

METHODS

Two raters analyzed MRI data and conventional radiographs from thirty-one subjects (n = 17 with ARM; n = 14 controls). We calculated intra-class correlation coefficients (ICCs) to test inter-rater reliability and applied paired t-tests to examine if SR parameters from MRI were comparable with those from pelvic radiograph. We further computed Pearson's correlation coefficients to test the linear relationship between SR calculated from MRI and conventional radiographs.

RESULTS

The ARM and control groups did not statistically differ in their age and weight on the day of the MRI scan. Reliability analysis revealed an excellent inter-rater agreement for SR from radiograph parameters with an intraclass correlation coefficient (ICC) of 0.94, respectively of 0.86 for MRI (frontal plane), and of 0.84 for MRI (sagittal plane). The correlation coefficient between SR calculated from the sagittal MRI and SR calculated from radiograph images was significant and high (r = 0.80, P < 0.001). The SRs from MRI images did not significantly differ from SRs from radiographs, but were also not statistically equivalent.

CONCLUSION

Our results demonstrate that the SR can be derived from MRI images with good inter-rater reliability. The SR value is marginal higher when calculated on MRI, presumably due to inclusion of cartilaginous yet unossified structures.

Laparoscopic Approach in Anorectal Malformations: How We Do It

Laparoscopy has a major role in the treatment of anorectal malformations (ARM) since Georgeson et al. introduced the laparoscopic assisted anorectoplasty in 2000. The majority of ARM can be repaired through a posterior sagittal incision without the need to enter the abdomen. Some ARM types require an abdominal approach to detach the rectum from the urinary tract in males or the vagina in females. Those malformations benefit from laparoscopy. In this article, we aimed to highlight the technical aspects relevant to the current laparoscopic repair of ARM.

Lasting impact on children with an anorectal malformations with proper surgical preparation, respect for anatomic principles, and precise surgical management

Optimal outcomes in the management of children with Anorectal Malformation (ARM) require careful surgical preparation and detailed understanding of the anatomic principles and operative setup. A clear understanding of operative anatomy and surgical principals guides decision making. Adherence to the principles of ARM repair, as well as the application of operative and imaging adjuncts, will yield the safest and most successful approach to ARM. In this review, we detail the surgical preparation, anatomic principles, and surgical management issues unique to ARM.