Utility Of Multi-detector Row Computed Tomography .
Original ArticlePlastic and Aesthetic ResearchUtility of multi-detector row computedtomography angiography versusDoppler in localization of perforators ofanterolateral thigh flapsChandan N. Jadhav1, Surinder Singh Makkar1, Gautam Biswas1, Niranjan Khandelwal2Department of Plastic Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India.Department of Radio Diagnosis, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India.12Address for correspondence: Dr. Chandan N. Jadhav, 4/126, Terrace Road, Perth, Western Australia 6000, Australia.E-mail: chandansurgery@gmail.comDr. Chandan N. Jadhav, MBBS, MS, MCh, Plastic Reconstructive and Aesthetic Surgeon, Fellowship Hand andMicrosurgery (Australia), DAFPRS Aesthetic Surgery Fellowship (Switzerland), Member of Editorial Boardfor Micromedicine-ABMS and reviewer for EJPS, Burns & trauma. Have several publications in indexed peerreviewed journals. Current research interests are in ADSC in fat grafts.ABSTRACTAim: Anterolateral thigh (ALT) flap is widely used in reconstruction of various defects.Preoperative imaging facilitates perforator mapping, overcoming intraoperative uncertainty. Thepurpose of this study was to investigate the utility of multi-detector row computed tomographyangiography (MDCTA) and a handheld Doppler in locating ALT perforators. Methods: Twentypatients were randomized into two groups. Group 1 patients received MDCTA and Dopplerstudies whereas Group 2 received only a Doppler study. The number, location, course, and sourceof all cutaneous and sizable perforators were compared with intraoperative findings. Surgeons’stress levels during flap harvest and flap harvest time were compared. Results: MDCTA findingscorrelated well with intraoperative findings for perforator type and segmental distribution with100% concordance. Doppler alone had a 52% rate of concordance. The sensitivity and specificityfor MDCTA in demonstrating the presence of perforators were 85.71% and 97.22%, respectively;whereas for Doppler alone the sensitivity and specificity were 80% and 87.91%, respectively. Indemonstrating perforator source, MDCTA showed a sensitivity of 100% and specificity of 91.66%,with 100% accuracy. Sensitivity and specificity for sizable perforators were 90% each, with 88.88%accuracy. Doppler studies were unable to provide this information. Comparison of surgeon stresslevels showed no differences between the two groups, although the time for flap harvest wassignificantly shorter in Group 1. Conclusion: MDCTA compared to Doppler is more sensitive,specific, and accurate with respect to location, course, and source of perforators.Key words:Anterolateral thigh; multi-detector row computed tomography angiography; perforatorAccess this article onlineQuick Response 264.2015.6452This is an open access article distributed under the terms of the Creative CommonsAttribution‑NonCommercial‑ShareAlike 3.0 License, which allows others to remix,tweak and build upon the work non‑commercially, as long as the author is creditedand the new creations are licensed under the identical terms.For reprints contact: service@oaepublish.comHow to cite this article: Jadhav CN, Makkar SS, Biswas G,Khandelwal N. Utility of multi-detector row computed tomographyangiography versus Doppler in localization of perforators ofanterolateral thigh flaps. Plast Aesthet Res 2016;3:52-8.Received: 31-05-2015; Accepted: 19-11-2015 2016 Plastic and Aesthetic Research Published by OAE Publishing Inc.
INTRODUCTIONThe anterolateral thigh (ALT) flap has become anincreasingly popular reconstructive option due to itsversatility of design, ability to be thinned and minimaldonor site morbidity. The major limitation of this flap isthe uncertainty in predicting perforator anatomy due tovariability in perforator size and course.[1] Formal analysisof these variations has not been adequately explored.Many authors have described the common location of ALTperforators as a tool in guiding flap harvest, but few havehighlighted the inconsistencies.[1] To improve operativeplanning, preoperative imaging is being increasinglyutilized. In the past, Doppler ultrasound has been usedfor perforator mapping, with most studies demonstratinghigh sensitivity but poor accuracy and high interobservervariability. Despite improvements in ultrasound technology,this technique has been frequently abandoned, and thereare trends toward performing no preoperative localizationat all.[2] Multi-detector row computed tomographyangiography (MDCTA) has become a powerful noninvasivealternative to conventional digital subtraction angiographyin preoperative imaging.[3-5] The utility of MDCTA forpreoperative planning in comparison with Doppler andeffectiveness of the ABC system in preoperative perforatorlocalization has not been studied in an adequate number ofpatients in the Indian population. The present randomizedcontrolled study was been designed to investigate theutility of preoperative imaging in the localization ofperforators and design of the skin paddle. Flap harvesttime, surgeon’s stress levels, and operative outcome werealso assessed.METHODSPatientsIn patients undergoing free ALT flaps, the goals were (1)to compare the number, location, course, and source ofcutaneous perforators with the use of preoperative MDCTAand a handheld Doppler device, with intraoperativeobservation as the gold standard; and (2) to compare thesubjective stress levels of the surgeon during perforatordissection and flap harvest time in patients who hadpreoperative MDCTA versus those who did not.The pilot study done between January and December 2011included all patients who required a free ALT flap. Patientswith a documented history of significant atheroscleroticdisease with blockage at the level of the infrarenal aorta,lower limb infections, scars, prior surgery to the thighs,and preexisting renal disease, diabetes, or cardiovasculardisease were excluded.Handheld Doppler localizationAll patients underwent preoperative perforatorlocalization using a handheld audible Doppler probe(Huntleigh Healthcare, 8 MHz, Cardiff, UK) performed byan independent assessor who was blinded to the MDCTAfindings. The patient was placed in the supine positionwith the leg straight in a neutral position. A line was drawnPlast Aesthet Res Vol 3 Issue 2 Feb 29, 2016connecting the anterior superior iliac spine (ASIS) to thesuperolateral corner of the patella (hereafter referred toas the AP line). The distance between these two pointswere measured, and the AP line was divided into 10 equalparts (hereafter referred to as segments) for the purposeof standardization between individuals and comparison.The Doppler signals were assessed at three main sites witha radius of 3 cm. A signal at the midpoint of the AP linecorresponded to segment 5, while the others 5 cm proximaland distal to midpoint corresponded to segments 4 and 6,respectively. The most audible signals were marked eachtime by the same observer in all patients. The distance ofthe Doppler signals from the AP line were plotted on theX-axis (horizontal) and from a perpendicular drawn at themidpoint of the AP line, on the Y-axis.Randomization into two groupsFollowing Doppler assessment, patients were randomizedinto two groups using computer-generated randomnumbers. Blocks of four were used to aid adequacy inrandomization. In the first group (Group 1), preoperativemapping of location, number, source vessel, and course ofall perforators of the ALT using an MDCTA was performed.In the second group (Group 2), no preoperative MDCTAwas performed.MDCTAMDCTA was performed using a 64-detector row computedtomography scanner with the following parameters: 120kVp, 80-120 mA, gantry rotation time 0.4 s, detectorconfiguration 16 mm 1 mm, 23 mm table travel perrotation, 512 512 matrix, and 180-240 field of view. Allscans were performed with intravenous (IV) administrationof 100 mL of nonionic iodinated contrast medium witha concentration of 300 mg/mL and injected at a rate of4 mL/s through an 18-gauge IV catheter inserted intoan antecubital vein. A bolus tracking technique wasemployed to obtain images from the point of bifurcationof the abdominal aorta to the level of the knee joint. Thevolumetric data acquired was then retrospectively used toreconstruct images with a slice thickness of 2 mm and areconstruction interval of 0.75 mm in a soft tissue kernel.Ten radio-opaque markers (1 cm diameter plastic buttons)were placed at equal intervals along the AP line to depicteach segment that assisted in accurate localization ofperforators on preoperative MDCTA, which were plottedon the X-axis and Y-axis or symbols were used todepict the distances as plotted on the graph keeping themidpoint of intersection of AP line as (0, 0). These werethen compared to the intraoperative findings.Operative techniqueAll patients underwent harvest of a free ALT flap usingthe anterior approach as described by Song et al.[6] andKoshima et al.[7] Seven out of 10 patients in Group 1 and9 out of 10 patients in Group 2 underwent subfascialdissection while suprafascial dissection was performed inthe remainder of cases. During flap harvest, the location ofeach cutaneous perforator was marked with a needle at aspecified distance from the perforator through the fascia53
into the skin. A mark was then made on the skin paddle atthis site. This point was then plotted on the X- and Y-axisafter resuturing the skin paddle (subtracting the specifieddistance) to eliminate the obliquity of perforator entrancesecondary to flap retraction/sagging. Care was taken toidentify all perforators to the skin paddle which werepreserved until the very end before committing to basethe flap on the sizable perforators.ten fasciocutaneous flaps (4 in Group 1 and 6 in Group 2),five musculocutaneous (MC) flap (2 in Group 1 and 3 inGroup 2), and one vastus lateralis muscle flap (in Group 1)were performed. Skin paddle size varied between 63 cm2and 264 cm2 in Group 1 and between 90 cm2 and 220 cm2in Group 2 with a mean of 173.78 cm2 and 170.10 cm2,respectively (P 0.89).Surgeons’ stress levelMDCTA picked up all seven septocutaneous (SC)perforators, 4/7 MC perforators of which 1/4 were semiseptocutaneous (SSC). There were no differences betweenMDCTA and intraoperative findings for the distribution oftype of perforators (P 0.68).Surgeon’s perceived (subjective) stress level during flapharvest was scored on a four-point visual analog scale (VAS)and recorded as follows: Grade 1 no stress (preoperative perforator locationmatched intraoperative findings with only minordiscrepancies ( 2 cm) in perforator location);Grade 2 mild stress (discrepancy measured morethan 2 cm in perforator location between preoperativeand intraoperative findings);Grade 3 moderate stress (gross difference in theperforator location, source, and course); andGrade 4 severe stress (no perforator was present,or inadvertent perforator injury occurred duringdissection).Perforator number and typePerforator sourceTime taken for flap harvest and surgical outcome werealso noted.Perforators were compared based on their source vessel:descending branch of the lateral circumflex femoral artery(DBLCFA), anteromedial thigh (AMT) perforator arisingfrom the DBLCFA, the transverse branch of the lateralcircumflex femoral artery (TBLCFA), or the oblique branchof the lateral circumflex femoral artery (OBLCFA). MDCTAaccurately detected 8 out of 9 perforators arising from theDBLCFA and 3 of the 4 perforators arising from the TBLCFA.Two AMT perforators were identified intraoperatively(both in Group 2). There were no differences betweenpreoperative MDCTA and intraoperative findings for thesource vessel and origin of the perforators (P 0.832).Statistical analysisSizable perforators Statistical Package for the Social Science, version 19, IBM(2010) was used. The Kolmogorov-Smirnov test was appliedto determine the distribution of data, and if data wasskewed, Mann-Whitney test was applied. For comparisonof categorical data, the Fischer exact and Chi-squared testswere applied. Kappa inter-rater agreement was applied todetermine agreement between the preoperative findingsof MDCTA versus Doppler using intraoperative findings asthe gold standard.RESULTSA total of 20 patients over a period of 1 year who underwentfree ALT flap coverage at our hospital were allocatedrandomly into two groups.Patient demographicsIn Group 1, the mean age of patients was 37.5 years 11.49 years, and in Group 2, it was 43 years 14.29 years(P 0.35). There was a total of six patients with post headand neck cancer resection defects (3 in each group) whileone patient in the Group 1 had invasive aspergillosis of themaxillary sinus. Eight patients had lower limb traumaticdefects (5 in Group 1 and 3 in Group 2), and five patientshad upper limb traumatic defects (1 in Group 1 and 4 inGroup 2). Traumatic limb defects accounted for 65% ofcases while nontraumatic defects accounted for 35%.Anterolateral thigh flap characteristicsFour cutaneous ALT flaps (3 in Group 1 and 1 in Group 2),54In our study, any perforator over 0.8 mm was consideredto be sizable.[8] MDCTA detected all sizable SC perforators,4/5 sizable MC perforators of which 1/2 was SSC. Dopplersignals localized sizable perforators accurately in only 2of 9 patients in Group 1 and 4 of 11 patients in Group2. Sizable perforators were further compared based ontheir source vessel, i.e. DBLCFA, DBLCFA-AMT, TBLCFA,or OBLCFA. MDCTA localized all sizable perforatorsarising from the DBLCFA and TBLCFA. Overall sensitivityand specificity of MDCTA in demonstrating the sizableperforator in segments 4 and 5 was 90% and had anaccuracy of 88.88% with a kappa value of 0.78 (goodagreement) for each segment.Concordance of MDCTA versus Dopplerfor perforator localizationA difference of more than 2 cm between preoperativelocalization and intraoperative findings was consideredto be discordant. In Group 1, MDCTA had a concordancelevel of 100% (12/12) while Doppler had concordanceof 46% (6/13). Overall concordance of Doppler wasonly 52% (13/25). This further establishes the accuracyof MDCTA in localization of perforators. The BlandAltman plot [Figure 1] was used to depict the inter-rateragreement between the two variables (MDCTA withintraoperative findings in the first plot and Dopplerwith intraoperative findings in the second plot) byplotting the average of the distance of perforatorsnoted by both the variables against its difference fromthe mean. This demonstrates that the values werePlast Aesthet Res Vol 3 Issue 2 Feb 29, 2016
closer to the mean in the MDCTA-intraoperative plot,indicating a good agreement in the locations of theperforators as compared to the Doppler-intraoperativeplot which was dispersed away from the mean.Surgeons’ stress levelsA VAS was used to record the level of stress experiencedby the surgeon during flap harvest. The differenceFigure 1: Bland-Altman plot for determining agreement betweenmulti-detector row computed tomography angiography, Doppler, andintraoperative perforator location. IO: intraoperative; SD: standarddeviationTable 1: Perioperative detailsPatient DiagnosisGroupbetween the mean VAS of Group 1 (2.1) and Group 2 (2.5)was not statistically significant (P 0.63). The differencebetween mean flap harvest time of Group 1 (87.5 min)and Group 2 (117.5 min) was not statistically significant(P 0.28). However, operator bias cannot be ruled out.Surgeon A (chief surgeon) performed an equal number ofsurgeries (five) in each group, of which two cases in eachgroup required an intramuscular perforator dissectionfor perforators arising from the DLBCFA. The differencebetween mean flap harvest time for Surgeon A in Group 1Figure 2: (a-c) Case 9: MDCTA coronal, sagittal, and axial section showingTBLCFAP-s 18 cm from ASIS. MDCTA: multi-detector row computedtomography angiography; ASIS: anterior superior iliac spine; TBLCFAP-s:septocutaneous perforator from transverse branch of lateral circumflexfemoral artery through ime(min)Type CTAType IODopplerMDCTA1111No perforatorMCSCSC, SCNo perforatorMC, SC, SCSC, SCSCNoYes, yesYes, yesNo, noYesYesYesYes, yesVL Grade 3B fracture lower one-third legCarcinoma buccal mucosaCarcinoma buccal mucosaType 3A maxillectomy defect(invasive aspergillosis)Carcinoma buccal mucosaTraumatic sole 2751157Forearm electrical burns1MC, SCMC, SSCNoYesDBLCFAP-vl210089Heel unstable scarTraumatic heel 0123410Traumatic heel defect1SSCNoYesDBLCFAP-vl1651112Carcinoma buccal mucosaTraumatic elbow defect22NANAMCSSC, SCNoNo, yesNANADBLCFAP-vlTBLCFAP-vl1485951314Grade 3B fracture lower 1/3 legType 4 maxillectomy defect(carcinoma maxillary sinus)Grade 3B fracture lower 1/3 legHand deglovingOpen wrist joint and hand defectGrade 3 B fracture mid 1/3 legCarcinoma buccal mucosaForearm contour correction22NANAMC, MCMCNoYesNANA3485125222222NANANANANANAMC, SCMC, SC (AMT)SCSCSCSCNoYesYes, noYesYesYesNANANANANANADBLCFAP-sDBLCFAP-vl sDBLCFAP-s1442111051802159585105151617181920AMTP: anteromedial thigh perforator; MDCTA: multi-detector row computed tomography angiography; DBLCFAP-s: descending branch lateralcircumflex femoral artery perforator through septum; DBLCFAP-vl: descending branch lateral circumflex femoral artery perforator through vastuslateralis; IO: intraoperative; MC: musculocutaneous; NA: not applicable; OBLCFAP-vl: oblique branch lateral circumflex femoral artery perforatorthrough vastus lateralis; SC: septocutaneous; SSC: semi-septocutaneous; TBLCFAP-vl: transverse branch lateral circumflex femoral artery perforatorthrough vastus lateralis; TBLCFAP-s: transverse branch lateral circumflex femoral artery perforator through septum; VAS: visual analog scale; VL: vastuslateralis; AMT: anteromedial thighPlast Aesthet Res Vol 3 Issue 2 Feb 29, 201655
Figure 3: Case 9: (a) Sensate ALT flap, LCFN included; (b) intraoperativesizable septocutaneous perforator (TBLCFAP-s) was 18 cm from ASIS asdetermined preoperatively by MDCTA; (c) 8 weeks postoperative showingwell settled sensate ALT flap; (d) posttraumatic heel defect with exposedcalcaneus. ALT: anterolateral thigh; LCFN: lateral cutaneous femoral nerve;ASIS: anterior superior iliac spine; MDCTA: multi-detector row computedtomography angiography; TBLCFAP-s: septocutaneous perforator fromtransverse branch of lateral circumflex femoral artery through spectrum(71 min) and Group 2 (95 min) was statistically significant(P 0.046). Perioperative details are shown in Table 1.Figures 2 and 3 are representative of case 9, and Figure 4 isrepresentative of case 4.DISCUSSIONThe vascular basis of the ALT flap has been extensively studiedsince its introduction by Song et al.[6] 30 years ago. Althoughanatomy of the lateral circumflex femoral source vessel isquite consistent, the perforators to the skin territory can havemultiple variations.[9] Various imaging modalities have beenused to predict the course and location of the perforators,of which MDCTA has been found to be the most consistent.[9]Perforator(s) number and typeIn the current study, MDCTA did not affect the choice of limb(whether right or left side) for flap harvest as compared toa study by Rozen et al.[1] The current study demonstratedan average of 1.45 perforators per limb, with 51.75%(15/29) SC and 48.25% (14/29) MC perforators. There wereno perforators in 5% (one) of the patients. These findingsdiffered from those published by Kimata et al.,[10] in which81.9% of the perforators were MC, 18.9% were SC, andthere was no perforator in 5% of the patients. In the currentstudy, SSC comprised 37.1% (5/14) of the total number ofMC perforators, which differs from
and neck cancer resection defects (3 in each group) while one patient in the Group 1 had invasive aspergillosis of the maxillary sinus. Eight patients had lower limb traumatic defects (5 in Group 1 and 3 in Group 2), and five patients had upper limb traumatic defects (1 in Group 1 and 4 in Group 2). Traumatic limb defects accounted for 65% of
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