A novel diagnostic aid for intra-abdominal adhesion detection in cine-MRI: pilot study and initial diagnostic impressions

Biomechanics of the abdominal wall before and after ventral hernia repair using dynamic MRI

PURPOSE

This study aims to investigate the use of dynamic MRI to assess abdominal wall biomechanics before and after hernia surgery, considering that such evaluations can enhance our understanding of physiopathology and contribute to reducing recurrence rates.

METHODS

Patients were assessed using dynamic MRI in axial and sagittal planes while performing exercises (breathing, coughing, Valsalva) before and after their abdominal hernia surgery with mesh placement. Rectus and lateral muscles, linea alba, viscera area, defect dimensions and hernia sac were contoured with semiautomatic process to quantify the abdominal wall biomechanical temporal modifications.

RESULTS

This study enrolled 11 patients. During coughing, the axial area of the hernia sac increased by 128.4 ± 199.2%. The sac increased similarly in axial and sagittal planes during Valsalva. Post-surgical evaluations showed a 26% reduction in inter-recti distance and a lengthening of all muscles (p ≤ 0.05). The post-operative rectus abdominis thickness change was negatively correlated with defect width during breathing (p ≤ 0.05). The largest change in linea alba displacement was observed in the surgical site (p = 0.07). Post-operatively, lateral muscles had a larger inward displacement during Valsalva (p ≤ 0.05). Rectus abdominis had a larger outward displacement during breathing (p = 0.09), reduced with the mesh size (p ≤ 0.05). A large inter-individual variability was observed.

CONCLUSION

Using a semi-automatic methodology, an in-depth analysis of the biomechanics of the abdominal wall was conducted, highlighting the importance of a patient-specific assessment. A broader study and consideration of recurrence would subsequently complete this methodological work.

Morphological features and molecular mechanisms in peritoneal adhesions from patients with chronic abdominal postoperative pain

BACKGROUND

Chronic abdominal pain affects 10-20% of all patients following abdominal surgery, with adhesions as a predominant cause. However, the biological mechanisms underlying adhesion-related pain are not fully elucidated. This study aimed to establish the morphological and molecular phenotype of adhesions in patients with and without chronic postoperative abdominal pain.

METHODS

In this case-control study, biopsies of adhesions were obtained from patients with chronic postoperative abdominal pain (related to adhesions on cineMRI) and controls without pain, from two tertiary care and one secondary care hospital. Quantitative histological analysis of haematoxylin and eosin-stained sections was performed, while immunohistochemical (IHC) markers for nerve tissue (S100, calretinin and synaptophysin) were quantified through image analysis. RNA expression of genes (TRPV1, BDNF, TAC1, TACR1, NGF) was measured using real time quantitative polymerase chain reaction (RT-qPCR). Controls were matched to cases by sex, age, and prior surgery, accepting small variations due to patient availability. An independent two-sided t-test was used to detect differences in IHC and RT-qPCR analysis between groups.

FINDINGS

Adhesions from 31 patients with pain were compared to those from 31 patients without pain, consisting of 48% connective tissue and 41% adipose tissue. Immunohistochemical analysis revealed increased nerve tissue in patients with pain (S100: median 597 ppm (range 92.2-3223.2 ppm) vs 151 ppm (range 15.2-1683.8 ppm) p < 0.001; calretinin: median 463 ppm (range 72.7-2996.5 ppm) vs 275 ppm (range 35.3-3194.8 ppm) p = 0.040). NGF showed a higher mRNA expression in adhesions from patients with pain compared to controls (p = 0.012).

INTERPRETATION

This study suggests a distinct morphological and molecular phenotype of adhesions in patients experiencing adhesion-related pain, providing insights into underlying mechanisms.

FUNDING

Veni grant from The Dutch Governmental Organisation for Health Research and Development (ZonMw grant number 91619035).

Preoperative diagnosis of adhesion severity between the abdominal wall and intestinal tract with novel abdominal ultrasound methodology to enhance surgical safety

BACKGROUND

Adhesions between the abdominal wall and intestinal tract from previous surgeries can complicate reoperations; however, predicting the extent of adhesions preoperatively is difficult. This study aimed to develop a straightforward approach for predicting adhesion severity using a novel abdominal ultrasound technique that quantifies the displacement of motion vectors of two organs to enhance surgical safety. The efficacy of this methodology was assessed experimentally and clinically.

METHODS

Using Aplio500T, a system we developed, we measured the displacement of the upper peritoneum and intestinal tract as a vector difference and computed the motion difference ratio. Twenty-five rats were randomized into surgery and nonsurgery groups. The motion difference ratio was assessed 7 days after laparotomy to classify adhesions. In a clinical trial, 51 patients undergoing hepatobiliary pancreatic surgery were evaluated for the motion difference ratio within 3 days preoperatively. Intraoperatively, adhesion severity was rated and compared with the motion difference ratio. A receiver operating characteristic curve was used to appraise the diagnostic value of the motion difference ratio.

RESULTS

In the animal experiment, the adhesion group exhibited a significantly higher motion difference ratio than the no-adhesion group (0.006 ± 0.141 vs 0.435 ± 0.220, P < .001). In the clinical trial, the no-adhesion or no-laparotomy group had a motion difference ratio of 0.128 ± 0.074; mild-adhesion group, 0.143 ± 0.170; moderate-adhesion group, 0.326 ± 0.153; and high-adhesion group, 0.427 ± 0.152. The motion difference ratio receiver operating characteristic curve to diagnose the adhesion level (≥moderate) was 0.938, indicating its high diagnostic value (cut-off 0.204).

CONCLUSION

This methodology may preoperatively predict moderate-to-high adhesions.

Evaluation of the Preoperative Slide Test in the Prediction of Intra-Abdominal Adhesions: A Single-Center, Double-Blinded, Prospective Observational Study

BACKGROUND

To evaluate the efficacy of the preoperative ultrasonographic sliding sign in predicting intra-abdominal adhesions.

METHODS

This was a single-center, double-blinded, prospective observational study undertaken from March and September 2021 on 110 patients with a history of previous abdominal surgery. All patients who were scheduled for laparoscopy underwent slide test in 5 zones of abdomen: right lower quadrant, left lower quadrant, previous operation site, vesicouterine pouch, and rectovaginal pouch. Adhesions were assessed by the same gynecologic surgeon using ultrasonography before the surgery and by gynecological surgeons during surgery, and by a third gynecologic surgeon to compare the preoperative slide test findings and laparoscopic findings after the surgery.

RESULTS

Seventy-three (66.4%) patients underwent laparoscopic surgery, and 37 (33.6%) patients underwent laparotomy. The mean age of patients was 46.9 ± 1.0 years. Sensitivity, specificity, and positive and negative predictive values of preoperative ultrasonography in predicting adhesions were 89.5%, 91.7%, 97.5%, and 71.0%, respectively. The accuracy of the slide test was calculated as 90.0%. It was found that as the total number of cesarean sections increased the estimates of vesicouterine adhesions and actual adhesions increased (P = .008). Also, the prediction of intra-abdominal adhesions and actual adhesions significantly increased as the total number of surgical operations increased (P = .002).

CONCLUSIONS

Intra-abdominal adhesions can be detected with the slide test, which is a non-invasive and well-tolerated procedure. Slide test can guide the physician before the elective operation in patients with previous abdominal surgery and may assist in counseling patients.

Quantifiable Measures of Abdominal Wall Motion for Quality Assessment of Cine-MRI Slices in Detection of Abdominal Adhesions

Abdominal adhesions present a diagnostic challenge, and classic imaging modalities can miss their presence. Cine-MRI, which records visceral sliding during patient-controlled breathing, has proven useful in detecting and mapping adhesions. However, patient movements can affect the accuracy of these images, despite there being no standardized algorithm for defining sufficiently high-quality images. This study aims to develop a biomarker for patient movements and determine which patient-related factors influence movement during cine-MRI. Included patients underwent cine-MRI to detect adhesions for chronic abdominal complaints, data were collected from electronic patient files and radiologic reports. Ninety slices of cine-MRI were assessed for quality, using a five-point scale to quantify amplitude, frequency, and slope, from which an image-processing algorithm was developed. The biomarkers closely correlated with qualitative assessments, with an amplitude of 6.5 mm used to distinguish between sufficient and insufficient-quality slices. In multivariable analysis, the amplitude of movement was influenced by age, sex, length, and the presence of a stoma. Unfortunately, no factor was changeable. Strategies for mitigating their impact may be challenging. This study highlights the utility of the developed biomarker in evaluating image quality and providing useful feedback for clinicians. Future studies could improve diagnostic quality by implementing automated quality criteria during cine-MRI.

Inter- and Intra-Observer Variability and the Effect of Experience in Cine-MRI for Adhesion Detection

Cine-MRI for adhesion detection is a promising novel modality that can help the large group of patients developing pain after abdominal surgery. Few studies into its diagnostic accuracy are available, and none address observer variability. This retrospective study explores the inter- and intra-observer variability, diagnostic accuracy, and the effect of experience. A total of 15 observers with a variety of experience reviewed 61 sagittal cine-MRI slices, placing box annotations with a confidence score at locations suspect for adhesions. Five observers reviewed the slices again one year later. Inter- and intra-observer variability are quantified using Fleiss’ (inter) and Cohen’s (intra) κ and percentage agreement. Diagnostic accuracy is quantified with receiver operating characteristic (ROC) analysis based on a consensus standard. Inter-observer Fleiss’ κ values range from 0.04 to 0.34, showing poor to fair agreement. High general and cine-MRI experience led to significantly (p < 0.001) better agreement among observers. The intra-observer results show Cohen’s κ values between 0.37 and 0.53 for all observers, except one with a low κ of −0.11. Group AUC scores lie between 0.66 and 0.72, with individual observers reaching 0.78. This study confirms that cine-MRI can diagnose adhesions, with respect to a radiologist consensus panel and shows that experience improves reading cine-MRI. Observers without specific experience adapt to this modality quickly after a short online tutorial. Observer agreement is fair at best and area under the receiver operating characteristic curve (AUC) scores leave room for improvement. Consistently interpreting this novel modality needs further research, for instance, by developing reporting guidelines or artificial intelligence-based methods.

Difficulty in predicting intra-abdominal adhesion before cesarean section: A case report

Severe adhesions between the bladder and uterus necessitated an atypical incision in the cesarean section of a woman with endometriosis. This could not be predicted with pre-surgery MRI. No methods in the literature are able to predict adhesions with true certainty; it is therefore still difficult to diagnose intra-abdominal adhesions.

Semiautomatic quantification of abdominal wall muscles deformations based on dynamic MRI image registration

Quantitative analysis of abdominal organs motion and deformation is crucial to better understand biomechanical alterations undermining respiratory, digestive or perineal pathophysiology. In particular, biomechanical characterization of the antero-lateral abdominal wall is central in the diagnosis of abdominal muscle deficiency. Here, we present a dedicated semiautomatic dynamic MRI postprocessing method enabling the quantification of spatial and temporal deformations of the antero-lateral abdominal wall muscles. Ten healthy participants were imaged during a controlled breathing session at the L3-L4 disc level using real-time dynamic MRI at 3 T. A coarse feature-tracking step allowed the selection of the inhalation cycle of maximum abdominal excursion. Over this image series, the described method combines (1) a supervised 2D+t segmentation procedure of the abdominal wall muscles, (2) the quantification of muscle deformations based on masks registration, and (3) the mapping of deformations within muscle subzones leveraging a dedicated automatic parcellation. The supervised 2D+t segmentation (1) provided an accurate segmentation of the abdominal wall muscles throughout maximum inhalation with a 0.95 ± 0.03 Dice similarity coefficient (DSC) value and a 2.3 ± 0.7 mm Hausdorff distance value while requiring only manual segmentation of 20% of the data. The robustness of the deformation quantification (2) was indicated by high indices of correspondence between the registered source mask and the target mask (0.98 ± 0.01 DSC value and 2.1 ± 1.5 mm Hausdorff distance value). Parcellation (3) enabled the distinction of muscle substructures that are anatomically relevant but could not be distinguished based on image contrast. The present genuine postprocessing method provides a quantitative analytical frame that could be used in further studies for a better understanding of abdominal wall deformations in physiological and pathological situations.

Clinical Perspective Concerning Abdominal Entry Techniques

OBJECTIVE

Entry into the abdomen during operative laparoscopy is a source of some controversy regarding the safest and most useful method. The objective of this review is to describe, compare, and contrast the most popular entry techniques.

DATA SOURCES

Data were collected from the historical starting point until present day from English language journal articles and book chapters.

METHODS OF STUDY SELECTION

Descriptive accounts dating back to the start of laparoscopy in the 1970s and spanning to present day well-designed randomized controlled trials and Cochrane reviews were compiled to evaluate the evidence for the effectiveness and safety of abdominal entry techniques.

TABULATION, INTEGRATION, AND RESULTS

The most common sites of entry are the umbilicus and the left upper quadrant. Between the Veress needle, direct trocar insertion, and open entry there is no high-quality evidence to suggest that any of these offers a universal safety advantage. The Veress needle is still the most used among gynecologists and facilitates primary trocar placement. Direct trocar entry under laparoscopic visualization may be underused, is faster, and may result in fewer failed entries. Open (Hasson) entry can be more technically challenging, but may be best for patients with suspected intra-abdominal adhesions.

CONCLUSION

Surgeon comfort is critical in choosing the entry site, method, and equipment. Surgeon familiarity with entry-failure troubleshooting, possible complications, and management is essential because major entry complications are rare in modern laparoscopy but critical because the essential steps of recognition and management can be lifesaving.

Does applied ultrasound prior to laparoscopy predict the existence of intra-abdominal adhesions?

Background/aim

The purpose of this study was to evaluate the efficacy of trans-abdominal ultrasonography (USG), a noninvasive diagnostic tool, in predicting the presence of intraabdominal adhesions, especially near the trocar entry area, to provide safe surgical access to the abdomen.

Materials and methods

Fifty-nine women with a previous history of open abdominal surgery (group A) and a group of 91 women with no previous history of surgery (group B) underwent dynamic ultrasound evaluation of the abdominal fields before laparoscopic operations. The anterior abdominal wall was divided into six quadrants: right upper, right lower, left upper, left lower, suprapubic, and umbilical. Adhesions were evaluated by surgeons during the operation and by radiologists using USG prior to the operation. Visceral organ movements greater than 1 cm was defined as normal visceral slide (positive test), with less than 1 cm of movement defined as abnormal visceral slide (negative test). Sliding test measures movements of omental echogenicity or a stable echogenic focus that corresponds to intestine peritoneal echogenicity that underlies abdominal wall during exaggerated inspiration and expiration. Adhesions observed during surgery were evaluated on a four-point scale, with 0 indicating no adhesions present, 1 indicating the presence of a thin, filmy avascular adhesion, 2 indicating the presence of a dense and vascular adhesion, and 3 indicating adhesions that connect surrounding organs with the overlying peritoneal surfaces. The McNemar test was used to compare the results of USG and laparoscopy for each measure.

Results

We found that preoperative USG was successful in identifying adhesions [sensitivity, 96.39% (95% CI 89.8–99.2); specificity, 97.43%]

Conclusion

Preoperative ultrasound examination of the abdominal wall may enhance the safety of abdominal entry during laparoscopic operations.

Evaluation of the diagnostic potential of trans abdominal ultrasonography in detecting intra-abdominal adhesions: A double-blinded cohort study

Background

Intra-abdominal adhesion is one of the most important complications of abdominopelvic surgery. It increases morbidity and mortality for patients. Although laparoscopy is the gold standard of adhesion diagnosis, it can cause visceral damage during the operation. Therefore, surgeons prefer to use non-invasive methods for planning the operation. We designed this study to evaluate transabdominal ultrasonography ( TAU) accuracy for diagnosing Intra-abdominal Adhesions

Material & methods

This double-blinded cohort study was conducted on 47 patients with previous laparotomy who undergo another surgery. Spontaneous visceral slide (SVS) and induced visceral slide (IVS) were measured during TAU.

Results

The mean age and BMI of 47 patients were 43.21±10.3 and 27.545±5.76. The majority of the patients were female (76%). Mean SVS and IVS in patients with intra-abdominal adhesion were 8.73±1.60 and 44.84±11.60. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of TAU in intra-abdominal diagnosis were 83.33%, 51.72%, 51.72%, 83.33%, 63.83%.

Conclusions

Although TAU is an appropriate method for detecting the intra-abdominal adhesion, it isn't good enough for diagnosing free adhesion area. We recommended further researches with greater sample size and other non-invasive techniques.

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Evaluation of accuracy, sensitivity, specificity, PPV, NPV for adhesion diagnosis.

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There are not a lot of studies on ultrasonography accuracy before.

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It’s an only double-blinded cohort study.

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Our study refers to high sensitivity and NPV for diagnosing the adhesion.