Three-dimensional display of the pelvic structure of anorectal malformations based on CT and MR images

Can transcutaneous perianal ultrasonography be the first-line diagnostic instrument for evaluating pediatric perianal fistulas?

BACKGROUND

Pediatric perianal fistula is a common disorder. It is more difficult to detect the fistula tract and internal opening (IO) in children than in adults. This study aimed to evaluate the clinical diagnostic value of transcutaneous perianal ultrasound for children with perianal fistula.

METHODS

A retrospective review was conducted by analysing the preoperative transcutaneous perianal ultrasound and intraoperative exploration results of 203 consecutive patients who were <3 years old and diagnosed with perianal fistula. Analyses were conducted to evaluate the accuracy and consistency of utilizing the transcutaneous perianal ultrasound in the diagnosis of the complexity and location of the IO of perianal fistulas.

RESULTS

Compared with intraoperative exploration, the preoperative transcutaneous perianal ultrasonography has almost perfect agreement (Kappa = 0.881, P < 0.001) in the diagnosis of fistula tract complexity and IO with a sensitivity of 92% and a specificity of 97%. In addition, both intraoperative exploration and transcutaneous perianal ultrasound diagnosis showed high consistency in the identification of the IO of perianal fistulas (Quadrant I Kappa = 0.831, Quadrant II Kappa = 0.773, Quadrant III Kappa = 0.735, Quadrant IV Kappa = 0.802, all P < 0.01). The IOs were mainly distributed in Quadrants IV and II in both simple and complex fistulas.

CONCLUSIONS

Transcutaneous perianal ultrasound, as a non-invasive and simple imaging technique, showed high accuracy in the diagnosis and identification of the fistula classification and IO location. It could be considered a first-line diagnostic instrument for evaluating perianal fistulas among children.

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.

Contrast-Enhanced Colosonography for the Evaluation of Children With an Imperforate Anus

This case series describes a novel method for showing the preoperative anatomy of children with anorectal malformations using ultrasound contrast, which we have termed "contrast-enhanced colosonography (ceCS)." Six patients with anorectal malformations without a perineal fistula were studied both by fluoroscopic distal colostography and ceCS, and their results were confirmed surgically. Contrast-enhanced CS precisely showed the complex anatomic relationships in all cases. Compared to traditional fluoroscopic studies, ceCS has the benefit of no associated ionizing radiation and thus is safer for children.

Study of pelvic floor and sphincter muscles in congenital pouch colon with the help of three-dimensional CT scan

INTRODUCTION

Congenital pouch colon (CPC) is a pouch-like dilatation of shortened colon associated with anorectal malformation (ARM). The disease is prevalent in northern India. Postoperatively, the continence results are not as good as in other ARMs and there is higher incidence of incontinence and perineal soiling in these patients. The present study aimed to evaluate the pelvic floor and sphincter muscle characteristics in patients of CPC with the help of 64-slice computerized tomography with three-dimensional (3D) volumetric reconstructions of images, thus, to know the overall quality of these muscles in the patients.

MATERIALS AND METHODS

The study was conducted in patients admitted over a period of July 2007 to November 2008 in our department. Totally, eight patients of CPC were subjected to 64-slice CT with three-dimensional reconstructions of images and different parameters such as quality of pelvic floor muscles, configuration of vertical and parasagittal fibres, shape and thickness of sphincter muscle complex, attenuation values of sphincters were studied.

RESULTS

The 3D reconstructed images of pelvis in patients of CPC showed a well-developed pelvic floor and sphincter muscle complex. The length of the parasagittal fibres, transverse width of the vertical fibres and CT attenuation values of these structures with overall muscle quality were found to be good in these patients.

CONCLUSION

In cases of CPC, the pelvic floor muscles including striated muscle complex (vertical and parasagittal fibres) are well developed. Higher rates of incontinence and soiling in CPC are not because of poorly developed pelvic floor and sphincter muscles. Three-dimensional CT can also provide important anatomical information that can help the operating surgeon while performing surgery.

Clinical value of pelvic 3-dimensional magnetic resonance image reconstruction in anorectal malformations

OBJECTIVE

The study aimed to build a 3-dimensional (3D) reconstruction of pelvic magnetic resonance images and evaluate the clinical value in anorectal malformations (ARMs).

METHODS

Magnetic resonance imaging (MRI) examinations were performed on a 1.5-T magnet. Sagittal, coronal, and transverse turbo spin-echo T1-weighted and fast spin-echo T2-weighted images of the pelvic region were obtained in 22 children. A 3D reconstruction was made on a computer and assisted by the 3D-Doctor software (Trial Version, Able Software Corp). The level and type of ARM and the developmental state of the striated muscle complex (SMC) were analyzed with 3D reconstruction image.

RESULTS

The 3D images of the pelvic were confirmed in 22 cases. Three-dimensional reconstructed images perfectly displayed the anatomical relationships of the SMC and the rectal atresia in these spaces. The 3D configuration of the SMC was different in each of the high- and low-type cases. The high-type malformation of SMCs differed particularly from the descriptions.

CONCLUSIONS

Pelvic magnetic resonance 3D reconstructed images were able to show the dimensional anatomical relations of pelvis, bladder, urethra, rectum, and SMC. Both a 3D image and positional information with MRI offers the surgeon a simulated operative profile of the SMC superior to MRI slices alone, which will help in providing morphological data for image diagnosis and operation of the ARM.

Experimental model for study of anorectal sphincter musculature by manometry and computerized tomography in piglets

There seems to be controversy on the anorectal sphincter presentation and anatomical division, as well as on its functional representation. Evaluation of the anorectal sphincter musculature has been achieved through several methods, including anorectal manometry and computerized tomography, but to date there is no experimental model allowing a detailed manometric study of this muscle complex. In this work, we have developed such a model, which should enable the manometric and radiographic study of the anatomical features and functional mechanisms of sphincteric injuries, as well as the assessment of drug effects on the anorectal musculature upon incontinence and constipation. Twenty-two piglets (aged 25-30 days, weighing 5-7 kg) were studied by anorectal manometry (rectoanal inhibitory reflex and vector volume) and computerized tomography (anorectal angle and anal canal length). The data obtained for the rectoanal inhibitory reflex, represented here as the average and standard deviation, were the following: relaxation duration = 14.75 +/- 3.62 s, sphincter basal pressure = 41.58 +/- 8.20 mmHg, relaxation index = 87.26 +/- 11.52%, speed of relaxation = 5.90 +/- 2.10 mm/s, and speed of relaxation recovery = 4.03 +/- 1.78 mm/s. As for the vector volume, results were as follows: vector volume = 2692.32 +/- 1298.12 mm Hg2 cm, sphincter length = 11.82 +/- 2.74 mm, high pressure zone length = 5.09 +/- 1.34 mm, maximum pressure = 61.50 +/- 20.58 mmHg, and asymmetry index = 43.50 +/- 10.03%. Radiographic evaluation led to the following results: anal canal length = 9.61 +/- 2.14 mm and anorectal angle = 137.91 +/- 7.75 degrees . The experimental model designed here allows both anorectal manometry and computerized tomography to be carried out in the same way it is performed in human beings, as long as animal sedation is strictly controlled.

Three-dimensional MRI of the male urethrae with implanted artificial sphincters: initial results

The aim of this study was to develop a method for simultaneous 3D visualization of a new type of artificial urethral sphincter (AUS) and adjacent urinary structures. Serial MR tomograms were acquired from seven men after AUS implantation. 3D reconstruction was performed by thresholding original (positive) and inverted (negative) image intensity and by subsequently fusing positive and negative images. Results show that the bladder, cuff and balloons of the AUS of originally high intensity were imaged in 3D by thresholding the positive datasets. The urethrae and corpora cavernosa penis of originally low intensity were displayed in 3D by thresholding the negative datasets. Fusion of the positive and negative datasets allowed simultaneous visualization of the AUS complex and adjacent urinary structures. All the structures of interest were also clearly seen by interactive multiplanar reformatting. Coronal tomographic datasets provided better 3D and reformatted 2D images than sagittal and transverse datasets. This technique offers a simple means for evaluating the complex urethral anatomy and the AUS, and has potential for improved 3D visualization of many other complex morphological and pathological conditions.