MSCT in evalutation of hernial sac volume using Valsalva's maneuver in patients with ventral hernias

Transcription

1 MSCT in evalutation of hernial sac volume using Valsalva's maneuver in patients with ventral hernias Poster No.: C-0794 Congress: ECR 2013 Type: Scientific Exhibit Authors: D. Petrenko, O. P. Sharmazanova, N. Bortnuy; Kharkiv/UA Keywords: Hernia, Diagnostic procedure, Decision analysis, Complications, CT, Abdomen DOI: /ecr2013/C-0794 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 19

2 Purpose Ventral hernias remain a very complex problem both for clinicians and radiologists. The actuality of treatment of ventral hernias is caused not only by the spread of this disease but also by the result of surgical treatment. Despite of the progress of world medicine in this field associated with the usage of mesh implants and tension-free surgical methods, the recurrence rates are nowadays about 25%. Abdominal imaging is more often determinant in selection of the method of treatment, during preoperative and postoperative periods, in detection of complications. Computed tomography (CT) and especially multislice computed tomography (MSCT) with its multiplanar capabilities are useful for detection ventral hernias of different types (1,2,3). The diagnosis of ventral hernia is based primarily on physical examination, which includes Valsalva's maneuver. Valsalva's maneuver is used to make the hernia more visible clinically, because the increase of intraabdominal pressure causes the hernia sac to enlarge and protrude through the anatomic defect. There were a few works which purpose was the usage of Valsalva's maneuver in MSCT (3,4). But we found no research that distinctly evaluated the changes of hernial sac volume, the appearance of possible risks and further usage of this data in surgery. The aim of our work was to evaluate the volume of hernial sac using MSCT with and without Valsalva's maneuver for characterization of ventral hernia concerning risks and surgical tactics. Images for this section: Page 2 of 19

3 Fig. 1: A woman with giant ventral hernia, 48 yo Page 3 of 19

4 Fig. 2: A man with giant ventral hernia, 45 yo Page 4 of 19

5 Methods and Materials There were sixteen patients (mean age 43 ±12, 10 women, 6 men) with suspected anterior wall hernias in our clinic. They underwent 16-MSCT on Toshiba Aquilion. The scanning was performed from the dome of the diaphragm to the inferior margin of the pubic symphysis. If a patient had obesity or a hernia had large size the level of scanning was prolonged to cover all the area of pathology. During examination patients received both oral and intravenous contrast material (Omnipaque) if there were no contraindications. Scans were acquired during native, arterial and the portal venous phase of enhancement, with a delay determined by bolus tracking and automated triggering technology. Protocols were modified depending on the situation. Basically it was 1 mm collimation, tube rotation was 0,75 sec (with a long scan length it was changed to 0,5 sec), helical pitch varied from 15,0 to 23,0. Immediately after basic scanning, with a small delay at the end of inspiration the patients were instructed to "strain", and the next data acquisition was performed during Valsalva's maneuver. There was no additional administration of contrast material. Technical parameters remained the same. On a workstation (Myrian) all the obtained scans with and without Valsava's maneuver were processed to get the next data set: areas of hernial sac at places of minimal and maximal herniation, height of hernial sac; presence, location and content of hernia and also transverse diameter of hernial orifice. Since hernial sac is rare present as a correct figure, the relative volume of hernial sac was calculated using acquired data in formula of truncated pyramid volume V= #h (Amax+#(AmaxAmin)+Amin). While evaluating maximal and minimal areas of hernial sac we took under consideration an error criterion of truncated figure, which experimentally was equal to 1 cm. It means the measurements were taken with an indent equal to 1 cm from upper and lower poles of hernial sac. Respectively we calculated the volume of hernial sac in rest and maximal hernial sac volume after Valsalva's maneuver application. The percent increase of hernial sac volume after Valsalva's maneuver, risk of incarceration and possible surface area of mesh implant were subsequently evaluated. Images for this section: Page 5 of 19

6 Fig. 3: A pattern of truncated pyramid volume calculation Fig. 4: Schematic pattern on 3D volume rendering model Page 6 of 19

7 Results In 16 patients ventral hernias were identified. 2 patiens (12,5 %) had small ventral hernias, 8 patients (50 %) had medium ventral hernias, 6 patients (37,5 %) had large and giant ventral hernias. After application of the maneuver there was an increase of hernial sac volume for more than 20 % in 2 patients (12,5 %), an increase of hernial sac volume from 10 to 20 % was in 7 patients (43,75%), an increase of hernial sac volume from 0 to 10 % was in 7 patients (43,75%). Parallel to mentioned above the transverse diameter of hernial orifice also changed. Obviously hernias become more evident after Valsalva's maneuver application. In 10 patients (62,5%) it was a quite clear increase of hernial sac volume. Note that behavior of hernia changes depending on its size during functional maneuvers. In distinction of large and giant ventral hernias where volume and content change extremely rare, in small and medium ventral hernias volume of hernial sac changes more often and from time to time the segment of bowel or abdominal fat become a content of the hernial sac. It's known that during life cycle abdominal cavity undergoes the acts of relaxation and tension. Such changeability creates an increased risk of incarceration that is partly simulated during application of Valsalva's maneuver. The correlation between changeability of hernial sac volume and risk of incarceration is quite clear. The less is the hernial sac volume, the higher are the changeability of its content and risk of incarceration. We recommend the next criteria depending on the changes of hernial sac volume: Percent increase of hernial sac volume Risk of hernia incarceration 0-10 % low % medium 20% and more high While evaluating the relative volume of hernial sac you should take under consideration that this volume "fell out" of the total abdominal cavity volume. With a long period of hernia disease abdominal cavity adapts to the absence of this volume and according to this intra-abdominal pressure changes. During the operation the abrupt return of the "lost" volume into the abdominal cavity takes place. An abrupt increase of intraabdominal pressure occurs, that can lead to Abdominal Compartment Syndrome (ACS) in this category of patients. To avoid this kind of complication, surgeons in different countries use different methods of preoperative preparation. One of them is preoperative progressive pneumoperitoneum (5,6,7). For this procedure it's appropriate to consider maximal hernial sac volume acquired only after Valsalva's maneuver application to reach maximal preoperative adaptation of abdominal cavity. For postoperative defect closure many surgeons prefer tension-free methods and mesh implants. The main aim of surgeon is to choose the right mesh implant and its right size. Page 7 of 19

8 The evaluation of maximal relative volume of hernial sac after Valsalva's maneuver helps to calculate the surface area of mesh implant and to find out the advisable volume of skin and subcutaneous fat excision. Mesh implant is usually square or rectangular in shape. Respectively the surface area to volume ratio is equal to 1/6. The formula of evaluation of recommended mesh implant surface area is As=Vmax/6. Images for this section: Fig. 5: Normal abdominal cavity without application of Valsalva's maneuver Page 8 of 19

9 Fig. 6: Normal abdominal cavity after Valsalva's maneuver application Fig. 7: Patient with small ventral hernia without Valsalva's maneuver. Note maximal area of hernial sac marked with yellow colour and transverse diameter of hernial orifice marked with blue colour. The content of hernial sac is abdominal fat. Page 9 of 19

10 Fig. 8: Patient with small ventral hernia after application of Valsalva's maneuver. There is a visible increase of maximal area of a hernial sac and transverse diameter of hernial orifice(an increase of hernial sac volume was more than 20 %). Abdominal fat became densier. Fig. 9: Evaluation of hernial sac height in patient with small hernia Page 10 of 19

11 Fig. 10: Patient with two ventral hernias. Note medium-sized hernia in paraumbilical region. The content of medium hernia is abdominal fat with a loop of small bowel in its orifice. Fig. 11: Patient with two ventral hernias after Valsalva's maneuver. Note that a loop of small bowel travelled into hernial sac with a parallel narrowing of hernial orifice(straight Page 11 of 19

12 risk of incarceration). Volume increase of hernial sac of medium hernia was more than 20%. Fig. 12: Evaluation of hernial sac height in medium hernia. Page 12 of 19

13 Fig. 13: Patient with two ventral hernias. Note right-sided large hernia that appeared at a place of postoperative drain. The content of large hernia are loops of large bowel and a segment of abdominal fat. Fig. 14: Patient with two ventral hernias after Valsalva's maneuver. An increase of volume of hernial sac was less than 10% with a parallel increase of transverse diameter of hernial orifice. Page 13 of 19

14 Fig. 15: Evaluation of hernial sac height in large hernia. Fig. 16: Patient with a giant ventral hernia. The content of hernial sac are loops of small and large bowel, abdominal fat. Page 14 of 19

15 Fig. 17: Patient with a giant ventral hernia after Valsalva's maneuver. An increase of hernial sac volume was about 10-20% with a parallel increase of trasverse diameter of hernial orifice. Fig. 18: Evaluation of hernial sac height in giant hernia. Page 15 of 19

16 Fig. 19: A chart of surface area and volume correlation Page 16 of 19

17 Conclusion The evaluation of hernial sac volume with MSCT using Valsalva's maneuver allows to obtain objective information for the surgeons: - risk of hernia incarceration - evaluation of volume loss for preoperative preparation - evaluation of possible mesh implant surface area Images for this section: Fig. 20: An application of mesh implant during operation using "onlay" technique in patient with giant ventral hernia. Page 17 of 19

18 Fig. 21: Postoperative condition of patient with giant ventral hernia. Page 18 of 19

19 References 1. Lee GHM, Cohen AJ. CT imaging of abdominal hernias. AJR 1993;161: Aguirre DA, Casola G, Sirlin CB. Abdominal wall hernias: MDCT findings. AJR Am J Roentgenol 2004;183: Aguirre DA, Santosa A.C., Casola G, Sirlin CB. Abdominal Wall Hernias: Imaging Features, Complications, and Diagnostic Pitfalls at Multi-Detector Row CT. RadioGraphics 2005; 25: Jaffe TA, O'Connell MJ, Harris JP, Paulson EK, DeLong DM. MDCT of Abdominal Wall Hernias: Is There a Role for Valsalva's Maneuver? AJR 2005;184: Dumont F, Fuks D, Verhaeghe P, Brehant O, Sabbagh C et al. Progressive pneumoperitoneum increases the length of abdominal muscles. Hernia 2009; 13: Szekeres P, Kremer I, Bukovacz R, Varga J. Preoperative progressive pneumoperitoneum in the treatment of giant abdominal hernias. Magy Seb 2007;60: Tanaka EY, Yoo JH, Rodrigues Jr. AJ, Utiyama EM, Birolini D, Rasslan S. A computerized tomography scan method for calculating the hernia sac and abdominal cavity volume in complex large incisional hernia with loss of domain. Hernia 2010; 14:63-69 Personal Information Dr. Dmytro Petrenko "Doctor Alex" clinic, radiology department Kharkiv, Ukraine dpet@ukr.net Page 19 of 19