Comparison of manual tracing versus a semiautomatic radial measurement method in temporal lobe MRI volumetry for pharmacoresistant epilepsy

Volumetric gain of the human pancreas after left partial pancreatic resection: A CT-scan based retrospective study

BACKGROUND/OBJECTIVES

Regeneration of the pancreas has been well characterized in animal models. However, there are conflicting data on the regenerative capacity of the human pancreas. The aim of the present study was to assess the regenerative capacity of the human pancreas.

METHODS

In a retrospective study, data from patients undergoing left partial pancreatic resection at a single center were eligible for inclusion (n = 185). Volumetry was performed based on 5 mm CT-scans acquired through a 256-slice CT-scanner using a semi-automated software.

RESULTS

Data from 24 patients (15 males/9 females) were included. Mean ± SD age was 68 ± 11 years (range, 40-85 years). Median time between surgery and the 1st postoperative CT was 9 days (range, 0-27 days; IQR, 7-13), 55 days (range, 21-141 days; IQR, 34-105) until the 2nd CT, and 191 days (range, 62-1902; IQR, 156-347) until the 3rd CT. The pancreatic volumes differed significantly between the first and the second postoperative CT scans (median volume 25.6 mL and 30.6 mL, respectively; p = 0.008) and had significantly increased further by the 3rd CT scan (median volume 37.9 mL; p = 0.001 for comparison with 1st CT scan and p = 0.003 for comparison with 2nd CT scan).

CONCLUSIONS

The human pancreas shows a measurable and considerable potential of volumetric gain after partial resection. Multidetector-CT based semi-automated volume analysis is a feasible method for follow-up of the volume of the remaining pancreatic parenchyma after partial pancreatectomy. Effects on exocrine and endocrine pancreatic function have to be evaluated in a prospective manner.

Seizure outcome 1 year after temporal lobe epilepsy: an analysis of MR volumetric and clinical parameters

BACKGROUND

The aim of this work was to determine predictors that may contribute to surgical success or failure. Relevant pre- and postoperative baseline data were analyzed, and temporal structures underwent a volumetric analysis.

METHODS

A total of 207 patients (107 female) underwent complete evaluation for epilepsy surgery. Prospectively collected data used for this analysis included the clinical and demographic data. Classic prognostic factors (e.g., gender, age at operation, age at epilepsy manifestation, duration of epilepsy, education, side of pathology, intracranial EEG recordings, secondarily generalized tonic-clonic seizures, etiological factors, histology) and a volumetric analysis of 12 temporal lobe subregions were used in a regression analysis to identify possible prognostic factors in surgery for TLE. Primary outcome measure was seizure freedom at 1 year and during the full first year expressed as class I in the ILAE outcome scale.

RESULTS

In the univariate analysis, we identified one negative predictor for a less favorable seizure outcome: intracranial EEG recordings (p = 0.010), hippocampal sclerosis as histological finding trended toward statistical significance (p = 0.054). No statistical outcome significance was found for preoperative temporal lobe compartment volume loss or postoperative lateral atrophy after mesial resection.

CONCLUSIONS

Necessity for intracranial EEG recording is an independent factor of not optimal seizure control in the 1-year follow-up. Preoperative temporal lobe volume differences including smaller mesial subcompartments did not correlate with poorer seizure outcome.

Comparison of semiautomated and manual measurements for simulated hypo- and hyper-attenuating hepatic tumors on MDCT: effect of slice thickness and reconstruction increment on their accuracy

RATIONALE AND OBJECTIVES

The aims of this study were to compare accuracy between semiautomated and manual measurements of the longest diameter and volume of simulated hepatic tumors in phantoms and to evaluate the effects of slice thickness (ST) and reconstruction increment (RI) on accuracy.

MATERIALS AND METHODS

Liver phantoms with 45 hypoattenuating and 45 hyperattenuating lesions of different sizes (diameter, 13.3-50.7 mm; volume, 0.4-54.0 mm(3)) and shapes (spherical or elliptical) were scanned using a 64-row multidetector computed tomographic scanner. Images were reconstructed with ST and RI settings of 0.75 and 0.7 mm, 1.0 and 0.7 mm, 1.5 and 1.0 mm, 3.0 and 2.0 mm, 3.0 and 3.0 mm, and 5.0 and 5.0 mm. The longest diameter and volume of each lesion were measured both manually and semiautomatically. To assess accuracy, measurements were compared to reference values by calculating absolute percentage error. Comparisons of absolute percentage error between methods and between ST and RI settings were performed using paired t tests. The degree of correlation between each measurement and a reference value was also assessed.

RESULTS

The semiautomated method showed significantly higher accuracy than the manual method in volume for most ST and RI settings (0.75 and 0.7 mm, 1.0 and 0.7 mm, and 1.5 and 1.0 mm in hypoattenuating lesions and all settings in hyperattenuating lesions; P < .05) and showed similar accuracy in diameter for all ST and RI settings regardless of lesion attenuation (P > .05). Semiautomated measurements also demonstrated higher correlation with reference values than the manual method for both diameter and volume. The absolute percentage error tended to be increased as ST and RI increased for both methods, and acceptable maximum ST and RI in semiautomated method were 1.5 and 1.0 mm.

CONCLUSIONS

Semiautomated computed tomographic measurement showed higher accuracy and correlation than the manual method in measuring the diameter and volume of hepatic lesions. The accuracy of both methods was highly dependent on z-axis resolution.

Randomized controlled trial of 2.5-cm versus 3.5-cm mesial temporal resection--Part 2: volumetric resection extent and subgroup analyses

BACKGROUND

This paper is addressing outcome differences in interesting subgroups from a previous randomized controlled trial of the extent of mesial temporal lobe resection (TLR) for drug-resistant epilepsy, by looking at effects of randomization, intended resection group, center, and true resection extent on seizure outcome.

METHODS

One hundred and seventy-nine cases with volumetrically assessed resection extent were used. Analyses of the extent of resection and subgroups and within subgroups for the two treatment arms will be performed, looking for confounding factors and using statistical methods (chi-square test, logistic regression analysis, and two-factorial ANOVA).

RESULTS

True resection extent varied considerably. Outcome comparison for right versus left resections, subgroups with mesial temporal sclerosis (MTS), or largest and smallest resections revealed no remarkable difference, compared to overall class I outcome. The intent-to-treat analyses within these subgroups revealed differences for class I outcome, albeit lacking in significance, except for better TLR outcome. Small true resection volume differences or randomization into the two resection groups could not explain the outcome differences between the selective amygdalohippocampectomy (SAH) and TLR subgroups. Logistic regression analysis showed an interaction between intended resection length and surgery type, confirming the impression of different impacts of the intended resection length under the two surgery types. The outcome difference between SAH and TLR was more likely explained by a center effect. In a two-factorial ANOVA for resected hippocampal volume, Engel outcome class I, and resection type, the outcome was not found to be correlated with true resection volume. A multifactorial logistic regression showed a mild interaction between the resection type with center on the Engel outcome class, extent of resection, and surgery type interacted, as did the extent of resection and center.

CONCLUSION

Patients with quite similar extent of resection can be seizure free or non-seizure free. In this cohort, seizure freedom rates fell again when the extent of mesial resection was maximized. Differences in class I outcome for SAH and TLR were not due to erroneous randomization, true resection extent, or presence of MTS, but were influenced by a center effect. Subgroup analyses did not help to provide arguments to favor one surgery type over the other.

Randomized controlled trial of 2.5-cm versus 3.5-cm mesial temporal resection in temporal lobe epilepsy--Part 1: intent-to-treat analysis

BACKGROUND

Only one prospective randomized study on the extent of mesial resection in surgery for temporal lobe epilepsy (TLE) exists. This randomized controlled trial (RCT) examines whether 3.5-cm mesial resection is leading to a better seizure outcome than a 2.5-cm resection.

METHODS

Three epilepsy surgery centers using similar MRI protocols, neuropsychological tests, and resection types for TLE surgery included 207 patients in a RCT with pre- and postoperative volumetrics. One hundred and four patients were randomized into a 2.5-cm resection group and 103 patients into a 3.5-cm resection group, i.e., an intended minimum resection length of 25 versus 35 mm for the hippocampus and parahippocampus. Primary outcome measure was seizure freedom Engel class I throughout the first year. The study was powered to detect a 20% difference in class I outcome. Seizure outcome was available for 207 patients, complete volumetric results for 179 patients. Outcome analysis was restricted to control of successful randomization and an intent-to-treat analysis of seizure outcome.

RESULTS

The mean true resection volumes were significantly different for the 2.5-cm and 3.5-cm resection groups; thus, the randomization was successful. Median resection volume in the 2.5-cm group was 72.86% of initial volume and 83.44% in the 3.5-cm group. At 1 year, seizure outcome Engel class I was 74% in the 2.5-cm and 72.8% in the 3.5-cm resection group.

CONCLUSIONS

The primary intent-to-treat analysis did not show a different seizure freedom rate for the more posteriorly reaching 3.5-cm resection group. It appears possible that not maximal volume resection but adequate volume resection leads to good seizure freedom.

Shrinkage of the hippocampal remnant after surgery for temporal lobe epilepsy: impact on seizure and neuropsychological outcomes

The aim of this study was to investigate the influence of the postoperative hippocampal remnant on postoperative seizure and neuropsychological outcome in temporal lobe epilepsy (TLE). Postoperative volumetric MRI measurements of 53 patients surgically treated for TLE revealed a postoperative volume loss of the hippocampal remnant compared with the respective preoperative segment in all patients. Extent of preoperative hippocampal pathology, remnant shrinkage, resection volume, and postoperative volume of the hippocampal remnant did not correlate with seizure outcome 1 year after surgery. With respect to neuropsychological outcome, performance on tasks assessing verbal memory and language-related functions was impaired in patients with left-sided pathology after surgery. Performance of patients with right-sided pathology (n=26) demonstrated no significant correlation with hippocampal measures or with neuropsychological data. Degree of hippocampal remnant shrinkage seems to be associated with decreased verbal memory performance in patients with left-sided TLE.

Volume determination of amygdala and hippocampus at 1.5 and 3.0T MRI in temporal lobe epilepsy

Since magnetic resonance imaging (MRI) technique is constantly evolving with higher field strength scanners, the question arises whether images from different field strength scanners can be used interchangeably for scientific and clinical purposes. We address this issue in a study group of patients with temporal lobe epilepsy (TLE). Two different quantification methods for analysing structural (MRI) were used. Conventional volumetry was performed by manually tracing amygdala and hippocampus volumes on both 1.5 and 3T scans of 10 TLE patients. Additionally a voxel-based morphometry (VBM)-based extraction of those structures was conducted. As an answer to the main question, it was determined that the volumetrically derived volumes of amygdala and hippocampus from 1.5 and 3.0T images did not differ. Our findings concerning the volumetry are consistent with findings in healthy controls, thus offering the possibility to use volumetry of the different scanners interchangeably. The results of the VBM-analyses show satisfying inter-scanner volume quantification but not consistent enough to be deemed interchangeable. Further investigations analysing the outcomes of conventional VBM of different field strength scanners are necessary.