Preoperative MRI Measurements Research Articles

Is early continence recovery related to the length of spared urethra? A prospective multicenter study comparing preoperative MRI and histologic specimen measurements after robotic radical prostatectomy

BackgroundUrinary incontinence (UI) is a common complication after radical prostatectomy, significantly affecting patients' quality of life. This study aimed to correlate the length of preserved urethra in robotic radical prostatectomy (RALP) patients with short-term urinary continence rates within 90 days post-surgery. MethodsA prospective multicentric study enrolled 190 prostate adenocarcinoma patients undergoing RALP. Using preoperative magnetic resonance imaging (mpMRI), urethral length was measured from the external urethral sphincter to the bladder neck. After surgery, histological measurements of the removed urethra were compared to the preoperative mpMRI data. Patients were categorized into two groups at the three-month follow-up based on urinary continence assessed through Urodynamic Study (UDS): Group A (94 patients without UI) and Group B (96 patients with UI). ResultsResults revealed a significant difference in mean UI recovery time (Group A: 12.35 days, SD: 3.09 vs. Group B: 93.86 days, SD: 34.8, p < 0.0001). A ROC curve identified a 16.5% cut-off value (p < 0.000, sensitivity 87.5%, specificity 91.8%). Both groups showed a significant negative correlation between preserved urethral percentage and UI recovery time (Group A: r −0.655, p < 0.0001; Group B: r −0.340, p: 0.017). Group A had an average of 21.52% preserved urethra, while Group B had 13.86% (p < 0.0001). At one-year follow-up, 93.2% overall patients reported urinary continence without pads. ConclusionsThis study emphasizes the positive correlation between preserved urethra percentage in RALP and early urinary continence recovery, highlighting its surgical significance.

Correlation between Preoperative MRI Parameters and Oswestry Disability Index in Patients with Lumbar Spinal Stenosis: A Retrospective Study.

Background and Objectives: Lumbar spinal stenosis (LSS) is a degenerative condition posing significant challenges in clinical management. Despite the use of radiological parameters and patient-reported outcome measures like the Oswestry Disability Index (ODI) for evaluation, there is limited understanding of their interrelationship. This study aimed to investigate the correlation between preoperative MRI parameters and ODI scores in patients with LSS undergoing surgical treatment. Materials and Methods: A retrospective analysis was conducted on 86 patients diagnosed with LSS over a 5-year period. Preoperative MRI measurements, including the cross-sectional area of the psoas muscle, lumbar canal stenosis, neural foramina area, and facet joint osteoarthritis, were assessed. ODI scores were collected preoperatively and at a 1-year follow-up. Statistical analyses were performed using IBM SPSS Statistics software (version 26). Results: Weak to moderate correlations were observed between certain MRI parameters and ODI scores. The initial ODI score had a weak positive correlation with the severity of lumbar canal stenosis according to Schizas criteria (rho = 0.327, p = 0.010) and a moderate negative correlation with the relative cross-sectional area of the psoas muscle (rho = -0.498, p = 0.000). At 1-year follow-up, the ODI had a weak negative correlation with the relative cross-sectional area of the psoas muscle (rho = -0.284, p = 0.026). Conclusions: While the severity of LSS showed a weak correlation with initial ODI, it was not a predictor of 1-year postoperative ODI. Furthermore, although the cross-sectional area of the thecal sac, the sagittal area of the neural foramen, and the grade of facet joint osteoarthritis influence the imagistic severity, none of them correlate with ODI. These findings underscore the need for a comprehensive model that integrates multiple imaging and clinical parameters for a holistic understanding of LSS and its functional outcomes.

Does Rotation and Anterior Translation Persist as Residual Instability in the Knee after Anterior Cruciate Ligament Reconstruction? (Evaluation of Coronal Lateral Collateral Ligament Sign, Tibial Rotation, and Translation Measurements in Postoperative MRI).

Purpose: The aim of this study was to evaluate the presence of residual instability in the knee after ACL reconstruction through the analysis of MRI findings. Methods: This study included patients who underwent isolated ACL reconstruction between December 2019 and December 2021, and had preoperative and postoperative MRI, clinical scores, and postoperative isokinetic measurements. The anterior tibial translation (ATT) distance, coronal lateral collateral ligament (LCL) sign, and femorotibial rotation (FTR) angle were compared preoperatively and postoperatively. The correlation between the changes in preoperative-postoperative measurements and postoperative measurements with clinical scores and isokinetic measurements was examined. The clinical outcomes were compared based on the presence of a postoperative coronal LCL sign. Inclusion criteria were set as follows: the time between the ACL rupture and surgery being 6 months, availability of preoperative and postoperative clinical scores, and objective determination of muscle strength using isokinetic dynamometer device measurements. Patients with a history of previous knee surgery, additional ligament injuries other than the ACL, evidence of osteoarthritis on direct radiographs, cartilage injuries lower limb deformities, and contralateral knee injuries were excluded from this study. Results: This study included 32 patients. After ACL reconstruction, there were no significant changes in the ATT distance (preoperatively: 6.5 ± 3.9 mm, postoperatively: 5.7 ± 3.2 mm) and FTR angle (preoperatively: 5.4° ± 2.9, postoperatively: 5.2° ± 3.5) compared to the preoperative measurements (p > 0.05). The clinical measurements were compared based on the presence of a postoperative coronal LCL sign (observed in 17 patients, not observed in 15 patients), and no significant differences were found for all parameters (p > 0.05). There were no observed correlations between postoperative FTR angle, postoperative ATT distance, FTR angle change, and ATT distance change values with postoperative clinical scores (p > 0.05). Significant correlations were observed between the high strength ratios generated at an angular velocity of 60° and a parameters FTR angle and ATT distance (p-values: 0.028, 0.019, and r-values: -0.389, -0.413, respectively). Conclusions: Despite undergoing ACL reconstruction, no significant changes were observed in the indirect MRI findings (ATT distance, coronal LCL sign, and FTR angle). These results suggest that postoperative residual tibiofemoral rotation and tibial anterior translation may persist; however, they do not seem to have a direct impact on clinical scores. Furthermore, the increase in tibial translation and rotation could potentially negatively affect the flexion torque compared to the extension torque in movements requiring high torque at low angular velocities.

Endometrioid adenocarcinoma: combined multiparametric MRI and tumour marker HE4 to evaluate tumour grade and lymphovascular space invasion

To assess the value of semi-quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and quantitative diffusion-weighted imaging parameters combined with human epididymis protein 4 (HE4) in predicting the pathological grade and lymphovascular space invasion (LVSI) of endometrioid adenocarcinoma (EAC). Between October 2018 and December 2021, 60 women (mean age, 55 [range, 32-77] years) with EAC underwent preoperative pelvic MRI and HE4 level measurements. The positive enhancement integral (PEI), time to peak, maximum slope of increase (MSI), and maximum slope of decrease were measured by manually drawing a region of interest on the neoplastic tissue. The receiver operating characteristic curve was used to calculate the diagnostic efficiency of the single parameter and combined factors. Lower apparent diffusion coefficients (ADCs) were observed in high-grade tumours (G3) than in low-grade tumours (G1/G2). PEI, MSI, and HE4 levels were higher in the high-grade tumours than in the low-grade tumours (p<0.05). The area under the curve (AUC) for G3 diagnosis using multiparametric MRI combined with HE4 was 0.929. ADC values were significantly lower in the EAC with LVSI than in those without LVSI. Tumours with LVSI showed higher PEI and HE4 levels than those without LVSI (p<0.05). The AUC for LVSI-positive diagnosis using multiparametric MRI combined with HE4 was 0.814. Semi-quantitative DCE-MRI, ADC values, and serum HE4 levels can be used to predict tumour grade and LVSI, and the prediction efficiency of multiparametric MRI combined with serum HE4 is better than that of any single factor.

Radiographic and MRI evidence of indirect neural decompression after the anterior column realignment procedure for adult spinal deformity.

The anterior column realignment (ACR) procedure, which consists of sectioning the anterior longitudinal ligament/annulus and placing a hyperlordotic interbody cage, has emerged as a minimally invasive surgery (MIS) for achieving aggressive segmental lordosis enhancement to address adult spinal deformity (ASD). Although accumulated evidence has revealed indirect neural decompression after lateral lumbar interbody fusion (LLIF), whether ACR serves equally well for neural decompression remains to be proven. The current study intended to clarify this ambiguous issue. A series of 36 ASD patients with spinopelvic mismatch, defined as pelvic incidence (PI) minus lumbar lordosis (LL) > 10°, underwent a combination of ACR, LLIF, and percutaneous pedicle screw (PPS) fixation. This "MIS triad" procedure was applied over short segments with mean fusion length of 3.3 levels, and most patients underwent single-level ACR. The authors analyzed full-length standing radiographs, CT and MRI scans, and Oswestry Disability Index (ODI) scores in patients with minimum 1 year of follow-up (mean [range] 20.3 [12-39] months). Compared with the preoperative values, the radiographic and MRI measurements of the latest postoperative studies changed as follows. Segmental disc angle more than quadrupled at the ACR level and LL nearly doubled. MRI examinations at the ACR level revealed a significant (p < 0.0001) increase in the area of the dural sac that was accompanied by significant (p < 0.0001) decreases in area and thickness of the ligamentum flavum and in thickness of the disc bulge. The corresponding CT scans demonstrated significant (all p < 0.0001) increases in disc height to 280% of the preoperative value at the anterior edge, 224% at the middle edge, and 209% at the posterior edge, as well as in pedicle-to-pedicle distance to 122%. Mean ODI significantly (p < 0.0001) decreased from 46.3 to 26.0. The CT-based data showing vertebral column lengthening across the entire ACR segment with an increasingly greater degree anteriorly suggest that the corrective action of ACR relies on a lever mechanism, with the intact facet joints acting as the fulcrum. Whole-segment spine lengthening at the ACR level reduced the disc bulge anteriorly and the ligamentum flavum posteriorly, with eventual enlargement of the dural sac. ACR plays an important role in not only LL restoration but also stenotic spinal canal enlargement for ASD surgery.

Can pre-operative MRI estimate hamstring autograft diameter in anterior-cruciate ligament reconstruction? (110)

Can pre-operative MRI estimate hamstring autograft diameter in anterior-cruciate ligament reconstruction? (110)

Prediction of quadriceps tendon-patellar bone autograft diameter in adolescents with 2-dimensional magnetic resonance imaging and anthropometric measures.

This study evaluates the correlation between the bone end and soft tissue end of the quadriceps tendon-patellar bone autograft (QPA) size and pre-operative MRI measurements of the quadriceps tendon along sections to be included in the graft harvest in adolescents. We also assessed association between graft diameter and anthropometric measures (height, weight, and BMI), age, and sex. Patients (10-18years) who underwent QPA ACL reconstruction and had a pre-operative MRI were considered for inclusion. Age, height, and weight, tibial and femoral side graft diameter, and patellar bone block dimensions were collected. Using a pre-operative 2D sagittal plane MRI, we measured the quadriceps at 10-mm increments above the patella, up to 40mm. We assessed correlation between the bone-end graft diameter and the AP measure at 10mm above the patella, and correlation between the soft-tissue end graft diameter and the most proximal AP measure. A total of 103 patients were included. A significant correlation between the soft-tissue side graft diameter and most proximal AP measurement was observed (rs = 0.51; p < 0.001). However, measurements significantly underestimated the soft-tissue end graft diameter (9.6 ± 0.8 vs. 7.4 ± 1.1; p < 0.001). There was no correlation between the bone-end graft diameter and AP measurement 10mm above the patella. Anthropometric measures were not associated with graft size. Skeletal maturity was associated with smaller graft size (p = 0.08). Soft-tissue end graft diameter is associated with the AP measure of the quadriceps at 20-40mm above the superior pole of the patella.

High failure rates following ligation of the intersphincteric fistula tract for transsphincteric anal fistulas: are preoperative MRI measurements of the fistula tract predictive of outcome?

Treatment of transsphincteric fistulas (TSFs) with fistulotomy after an indwelling seton is tempered by risks of incontinence and litigation. Thus, ligation of the TSF tract has been popularized as an alternative option. We previously reported on 107 patients who underwent ligation of the intersphincteric fistula tract (LIFT), with a 46% failure rate. Posterior fistula was the only predictor of recurrence. The aim of the present work was to investigate whether the length, width or depth of the fistula measured on preoperative MRI was correlated with recurrence. Following institutional review board approval, a retrospective analysis of our prospective Complex Anal Fistula Database from 1 January 2011 to 31 August 2019 was performed. Patients with TSF who underwent preoperative MRI and LIFT were included. Fistula location was classified as anterior, posterior or lateral. MRI measurements of fistula length, width and depth (in the intersphincteric groove) were performed. The type and rate of postoperative recurrence were analysed. 173 patients underwent MRI for an anal fistula; of these 40 underwent LIFT and 22/40 (55%) had preoperative MRI. There was no difference in the length, width or depth of anterior (n=9), posterior (n=7) or lateral (n=6) fistula tracts. The overall recurrence rate was 9/22 (41%). Posterior TSFs had the highest recurrence rate (5/7, 71%). The mean length, width, and depth of the fistula tract, measured at the preoperative site of LIFT in the intersphincteric groove, did not correlate with recurrence regardless of fistula location.

Assessment of the anterior osteotomy role in the restoration of normal pelvic floor anatomy for bladder exstrophy patients using pre and postoperative pelvic floor MRI

Our aim was to evaluate the effectiveness of anterior osteotomy in the restoration of normal pelvic floor anatomy in classic bladder exstrophy repair using pelvic floor MRI as an imaging tool for evaluation. This study is a pilot prospective randomized controlled study that included 20 infants with classic bladder exstrophy older than three months with no history of previous surgical operations. All patients underwent complete primary repair and were randomized into two groups, with or without osteotomy. Both groups were assessed preoperatively & postoperatively after three months with pelvic floor MRI and compared to age & gender-matched control group infants with normal pelvic anatomy infants who underwent pelvic MRI for other medical conditions. There was not any significant statistical difference between osteotomy and non-osteotomy groups in pre-operative demographic data and all pelvic floor MRI measurements, emphasizing that both groups were equal in all characters at the start point of the study before the operation. The mean change difference between pre-operative and post-operative pelvic floor MRI measurements were compared in both groups, and there was not any significant statistical difference in all pelvic floor MRI measurements. Both groups showed the same statistical significance when compared with the control group in all pelvic floor MRI measurements except the posterior bladder neck distance, which was in favor of the osteotomy group, closer to the normal pelvic floor anatomy. Anterior osteotomy did not have a significant difference in the restoration of the normal pelvic floor anatomy when combined with complete primary repair of classic bladder exstrophy in newly diagnosed neonates older than three months, except for a single measurement, posterior bladder neck distance. Future studies needed to determine the effect of osteotomy on continence.

Pre-operative MRI measurements versus anthropometric data: Which is more accurate in predicting 4-stranded hamstring graft size in anterior cruciate ligament reconstruction?

Background/objectiveGraft diameter has been shown to play an important role in anterior cruciate ligament (ACL) autograft failure rates. The roles of pre-operative MRI measurement of graft size and anthropometric data have been studied in the prediction of hamstring graft size. Pre-operative knowledge of hamstring graft diameter allows surgeons to perform better surgical planning and provides an opportunity to discuss with patients on alternative graft options such as allografts should the need arises. The purpose of this study was to compare the accuracy of pre-operative anthropometric data and MRI measurements in the prediction of 4-stranded hamstring autograft size in anterior cruciate ligament reconstruction. MethodThis was a cohort study involving 141 subjects (115 males and 26 females) who underwent a single bundle ACL reconstruction utilising a 4-stranded hamstring graft by a single surgeon from 2008 to 2012. Pre-operatively, the height, weight, body mass index (BMI), age, gender and smoking status was recorded. The MRI scans used for diagnosis were utilized to measure the gracilis (GT) and semi-tendinosus (ST) cross sectional area (CSA). ResultWe found the strongest correlation between Combined (ST + GT) CSA and intra-operative graft size (r = 0.596, p < 0.001). This was followed by ST CSA (r = 0.570,p < 0.001), Body surface area (r = 0.507,p < 0.001), and GT CSA (r = 0.460,p < 0.001). No significant correlation was found between 2 anthropometric data (Age and BMI). There was also no significant difference between different strengths of MRIs (1.5T vs 3.0T) in determining the intra-operative graft size (p = 0.438). ConclusionWe conclude that pre-operative MRI is superior to anthropometric variables in predicting the size of 4-stranded hamstring autografts used in ACL reconstruction.

Valgus Correctability and Meniscal Extrusion Were Associated With Alignment After Unicompartmental Knee Arthroplasty.

Appropriate postoperative lower limb alignment is one important element of a successful unicompartmental knee arthroplasty (UKA). To predict postoperative alignment, it is important to investigate the association between preoperative imaging evaluations and lower limb alignment after medial UKA. (1) Do preoperative valgus stress radiographic and MRI measurements (% mechanical axis, hip-knee-ankle angle, medial meniscal extrusion distance, and osteophyte area at the medial femur and tibia) correlate with postoperative lower limb alignment after UKA; and (2) Can useful cutoffs be calculated in advance of surgery for those findings that were associated with coronal-plane overcorrection? We retrospectively analyzed 125 patients with medial knee pain who underwent UKA from January 2012 to October 2018. Valgus stress radiography and MRI were performed routinely to assess the knee. Valgus stress radiography was obtained with the patient supine with the knee in full extension and a firm manual valgus force applied to the knee. Full-length weightbearing radiography was performed 3 months after surgery. There were 12% (15) of patients who did not undergo MRI, and 4% (five) of patients who did not receive the postoperative full-length weightbearing radiograph and they were excluded, leaving 84% (105) of patients available for analysis. There were 27 men and 78 women with a mean (range) age of 77 years ± 6 years (60 to 87). The preoperative diagnosis was medial osteoarthritis in 99 patients and osteonecrosis of the medial femoral condyle in six. To investigate the associations, we routinely measured % mechanical axis using radiography, and also measured the medial meniscal extrusion distance and osteophyte area at the medial femur and tibia using MRI after surgery. Medial meniscus extrusion distance was defined as the distance from the outermost edge of the medial meniscus to a line connecting the femoral and tibial cortices. From these parameters, postoperative alignment was estimated using regression and receiver operating characteristic curve analyses. Variables with p < 0.05 were included. The % mechanical axis on the valgus stress radiograph and medial meniscal extrusion distance were correlated with postoperative lower limb alignment after UKA (adjusted correlation coefficient 0.72; p < 0.001, adjusted correlation coefficient 0.2; p = 0.003, respectively). The estimated % mechanical axis on the postoperative weightbearing radiograph was equal to -0.27 + 0.86% (% mechanical axis on valgus stress radiograph) + 1.14 mm (medial meniscal extrusion distance). Using a cutoff point of 36%, the % mechanical axis on valgus stress radiograph was associated with overcorrection after UKA (area under the curve: 0.89; odds ratio 14 [95% CI 0.75 to 0.95]; p < 0.001, sensitivity 77.8%, specificity 80.9%). The overcorrection of a varus knee on a valgus stress radiograph before UKA and the increased extrusion of the medial meniscus on preoperative MRI was associated with a greater likelihood of overcorrected alignment after UKA. Future studies should conduct long-term follow-up of malalignment patients to assess the possible complications. Level III, diagnostic study.

Magnetic resonance imaging predictors of shoulder instability in adolescents.

Managing recurrent shoulder instability in an athlete of any age is challenging. The pediatric literature regarding recurrence of instability is difficult to interpret because of the variable treatment protocols and varying ages. The adult literature suggests that bone loss on the humerus, glenoid or both, as detected by CT, has high rates of recurrence following surgical intervention. The purpose of this study was to evaluate risk factors for recurrence following arthroscopic capsulorrhaphy in adolescent athletes using preoperative MR arthrograms. We reviewed a retrospective shoulder instability database for adolescents (age ≤18years), who underwent an isolated arthroscopic capsulorrhaphy from 2006 to 2011. We recorded preoperative MRI measurements regarding the dimensions of the glenohumeral joint, as well as glenoid, humeral and labral pathologies. We performed statistical analysis to determine MRI findings that might have predicted recurrence of shoulder instability following capsulorrhaphy. We reviewed a total of 50 patients (13-18years) and found 22 patients (44%) to have recurrent instability following capsulorrhaphy. Presence of glenoid bone loss or a bipolar bone lesion (defined as bone loss on both the glenoid and humerus) significantly predicted recurrence of shoulder instability (both P=0.03). There was not a threshold size of glenoid bone loss or bipolar lesion that predicted recurrence. All remaining glenohumeral dimensions or presence or size of an isolated Hill-Sachs did not significantly predict recurrence of instability. Athletes ≤18years old have a high rate of failure following arthroscopic capsulorrhaphy in the presence of glenoid bone loss or a bipolar lesion on MRI. Surgeons should consider addressing these lesions in adolescent athletes with shoulder instability. Additionally, MRI is a valid imaging tool to diagnose and measure osseous lesions of the shoulder.

Correlation of intra-operative hamstring autograft size with pre-operative anthropometric and MRI measurements

The purpose of this study was to compare various pre-operative methods of estimating intra-operative hamstring autograft size. A retrospective review was completed on 74 patients who had an anterior cruciate ligament reconstruction performed using a quadruple-looped hamstring autograft from July 2007–April 2015 at a single institution. A positive correlation was observed between intra-operative graft size and pre-operative imaging using two methods of MRI measurements. Correlation existed between hamstring size and patient height and weight, but not age or BMI. Thus, pre-operative MRI and anthropometric measurements can be used to estimate intra-operative hamstring graft size.

516 (PB-149) - Analsysis of tumor size between imaging of preoperative ultrasound, MRI and pathologic measurements in early breast carcinoma

516 (PB-149) - Analsysis of tumor size between imaging of preoperative ultrasound, MRI and pathologic measurements in early breast carcinoma

Correlating pre-operative MRI measurements of metatarsal Osteomyelitis with surgical clean margins reveals the need for a one centimeter resection margin

BackgroundDue to the high incidence of forefoot ulcerations with associated osteomyelitis, there has been an increased demand for partial ray amputations. In order to ensure complete removal of infected metatarsal bone, a clean margin amount is chosen based on the surgeon’s intraoperative visual subjective evaluation. The margin is resected and sent to pathology. Currently the literature shows positive proximal margin rates of 35–40%. The purpose of this study was to reduce the rate of positive proximal margins by effectively resecting all infected bone using pre-operative MRI measurements with an added resection margin.MethodsTwenty-four osteomyelitis positive metatarsals were included in this exploratory study. The distance of proximal osteomyelitic extension within the metatarsal was measured on MRI in centimeters. Intra-operatively, the partial ray amputation cut was determined by adding an extra 0.5 cm resection margin to the MRI measurement. At the study’s mid-point, bone histopathology revealed an increase in positive proximal margin rates-so the resection margin was increased to 1 cm. Descriptive outcomes included the mean distance of osteomyelitis propagation, proximal margin rates, as well as diagnostic statistics.ResultsAfter removing the specimens with false positive MRI results, the study sample included 21 metatarsals positive for osteomyelitis. A 0.5 cm resection margin proximal to the osteomyelitis resulted in a 50% positive proximal margin rate. After increasing the resection margin to 1 cm, there was found to be an improved positive proximal margin rate of 9%. Based on MRI findings, the mean distance + standard deviation of osteomyelitis propagation along the metatarsal proximally was 1.81 cm + 0.74 cm. The metatarsal specimen was processed by pathology into multiple pieces and compared to MRI, resulting in MRI sensitivity of 67%, specificity of 74%, positive predictive value of 79%, and negative predictive value of 60%.ConclusionsBy performing a 1 cm resection margin proximal to the metatarsal osteomyelitis the proximal margin rate was reduced to clinically meaningful levels. These preliminary findings support using a 1 cm resection margin when performing any form of metatarsal amputation, to reduce the risk of residual osteomyelitis post-operatively.Trial registrationSt. Luke’s Hospital, IRB National Protocol ID SLHN2015–112. Date:1–13-16.

Preoperative measure of individualized anatomic ACL reconstruction in west Chinese patients: Correlation between preoperative MRI and intra-operative measurements

Preoperative measure of individualized anatomic ACL reconstruction in west Chinese patients: Correlation between preoperative MRI and intra-operative measurements

Impact of skull base development on endonasal endoscopic surgical corridors

Scarce morphometric data exist on the developing skull base as a corridor for endonasal endoscopic approaches (EEAs). Furthermore, the impact of skull base lesions on its development has not been assessed. The authors describe a novel set of anatomical parameters characterizing the developmental process as well as the utility of these parameters in preoperative planning and a feasibility assessment of EEAs for neurosurgical treatment of skull base lesions in children. Based on specific MRI sequences in 107 pediatric patients (2-16 years of age) without skull base lesions (referred to here as the normal population), 3 sets of anatomical parameters were analyzed according to age group and sex: drilling distance, restriction sites, and working distance parameters. A separate set of patients undergoing EEAs was analyzed in similar fashion to address the impact of skull base lesions on the developmental process. The volume of the sphenoid sinus significantly increases with age, reaching 6866.4 mm(3) in the 14-16 years age group, and directly correlates with the pneumatization type (r = 0.533, p = 0.0001). The pneumatization process progresses slowly in a temporal-posterior direction, as demonstrated by the growth trend of the sellar width (r = 0.428, p = 0.0001). Nasal restriction sites do not change significantly with age, with little impact on EEAs. The intercarotid distance is significantly different only in the extreme age groups (3.9 mm, p = 0.038), and has an important impact on the transsphenoidal angle and the intracranial dissection limits (r = 0.443, p < 0.0001). The 14.9° transsphenoidal angle at 2-4 years has a 37.6% significant increase in the 11-13 years age group (p = 0.001) and is highly dependent on pneumatization type. Age-dependent differences between working parameters are mostly noted for the extreme age groups, such as the 8.6-mm increase in nare-vomer distance (p = 0.025). The nare-sellar distance is the only parameter with significant differences based on sex. Skull base lesions induce a high degree of variance in skull base measurements, delaying development and decreasing parameter values. Skull base parameters are interdependent. Nare-sellar distance can be used to assess global skull base development because it highly correlates with the intercarotid distance in both the normal population and in patients harboring skull base lesions. Skull base development is a slow, gradual, age-dependent, sex-independent process significantly altering endonasal endoscopic corridors. Preoperative MRI measurements of the pediatric skull base are thus a useful adjunct in choosing the appropriate corridor and in assessing working angles and limits during dissection or reparative surgery. Skull base lesions can significantly impact normal skull base development and age-dependent growth patterns.

Alignment for total knee replacement: a comparison of kinematic axis versus mechanical axis techniques. A cadaver study

Standard instrumentation tries to reproduce mechanical axes based on mechanical alignment (MA) guides. A kinematic alignment (KA) technique derives its plan from pre-operative MRI-measurements. This matched-pair cadaveric study compared the resulting postoperative alignments. A prospective series of 12 torsos were acquired for a total of 24 limb specimens including intact pelvises, femoral heads, knees, and ankles.The cadavers received MRI scans to manufacture the kinematic alignment cutting guides. Two investigating surgeons performed total knee arthroplasties on randomly chosen sides using MA instruments. On the contralateral sides, KA cutting guides were used. A navigation system was used to measure final alignment. The overall alignment showed no significant differences between the systems. In the MA group the differences between the planned and the final implantation regarding overall limb alignment ranged between 0.2° and 6.2°. In the KA group the differences between the planned and final implantation regarding overall limb alignment ranged between 0.3° and 9.1°. The differences of the deviation from plan for overall limb alignment showed no significant differences between the methods. The different alignment strategies resulted in variations of the combinations of the three-dimensional component position on the femur and the tibia. However, the legs were aligned within comparable range for both chosen techniques.

Hepatic steatosis assessment with CT or MRI in patients with colorectal liver metastases after neoadjuvant chemotherapy

Preoperative radiological assessment of hepatic steatosis is recommended in patients undergoing a liver resection, but few studies investigated the diagnostic accuracy after neoadjuvant chemotherapy. The aim of this study was to compare diagnostic accuracy of preoperative CT or MRI measurements of steatosis in patients with colorectal liver metastases after induction chemotherapy. MRI measurements (relative signal intensity decrease; RSID), N = 36, and CT scan measurements (Hounsfield units; HU), N = 32, were compared with histological steatosis assessment. Diagnostic accuracy was determined for detecting any (>5%) or marked macrovesicular steatosis (>33%). MRI showed the highest correlation with histology (r = 0.82, P < 0.001), compared to CT measurements (r = -0.65, P < 0.001). Based on linear regression analysis, radiological cut-off values for 5% and 33% macrovesicular steatosis, corresponded to 0.7% and 19.2% RSID in the MRI-group, and 60.4 and 54.2 HU in the CT-group, respectively. Sensitivity and specificity for the detection of any and marked macrovesicular steatosis using MRI was 87% and 69%, and 78% and 100%, respectively, and for CT, 83% and 64%, and 70% and 87%, respectively. In patients treated with neoadjuvant chemotherapy MRI measurements of steatosis showed the highest correlation coefficient and the best diagnostic accuracy, as compared to CT measurements.

Significance of the Tentorial Alignment in Approaching the Trigeminal Nerve through the Suboccipital Retrosigmoid Technique

Introduction: In this study, we aimed at assessing the significance of the tentorial alignment in approaching the trigeminal nerve through a suboccipital retrosigmoid craniotomy. Methods: Four parameters were evaluated using preoperative MRI and intraoperative measurements in 34 consecutive patients who underwent microvascular decompression of the trigeminal nerve via a suboccipital retrosigmoid approach: (1) the angle between the tentorium and the line drawn from the hard palate (tentorial angle, TA); (2) the angle between the tentorium and the line connecting the opisthion to the inion (occipital angle, OA); (3) the angle between the lines drawn along the petrous bones ventral to the internal auditory canals (petrous angle, PA); (4) the intraoperative distance between the trigeminal nerve and the acousticofacial bundle (distance, d). Statistical analysis was performed using Pearson's correlation test and t-test as appropriate. Results: Mean values were 50.1 ± 12.2 for TA, 82.3 ± 9.9 for OA, 104.6 ± 12.2 for PA, and 3.2 ± 1.5 mm for d. There was a negative correlation between TA and d (r = − 0.233, p = 0.09): the mean d was 3.7 ± 1.7 mm for TA 51 (p = 0.06). A positive correlation was detected between TA and OA (r = 0.336, p = 0.02). Conclusions: The distance between the trigeminal nerve and the acousticofacial bundle decreases in the presence of a steep tentorial angle. This limits the working field at the petrotentorial sulcus. Awareness of such anatomical features at the time of preoperative planning is of paramount importance to avoid complications during the procedure.