Delineation Protocol Research Articles

Long-term Outcomes Following Individualized Elective Primary Tumor CTV Delineation Based on Stepwise Spread Patterns of Nasopharyngeal Carcinoma Treated with Intensity-modulated Radiotherapy.

Our institution has developed an individualized elective primary tumor clinical target volume (CTVp) delineation protocol for nasopharyngeal carcinoma (NPC) based on stepwise tumor spread patterns in intensity-modulated radiotherapy (IMRT) for over ten years. Herein, we report the long-term efficacy and toxicities in NPC patients treated under this protocol. A total of 7,262 histologically proven, nonmetastatic NPC patients treated with IMRT following this individualized delineation protocol were retrospectively evaluated. The 5-year rates for local relapse-free survival (LRFS), regional relapse-free survival (RRFS), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS) were estimated. Dose-volume histogram (DVH) parameters for patients with local relapse were compared to those of propensity score-matched (PSM) without local relapse. Dosimetric comparisons of our delineation protocol with the 2018 International Guideline (2018-IG) were conducted on representative early- and advanced-stage NPC cases. The 5-year LRFS, RRFS, DMFS, PFS and OS were 93.6%, 94.4%, 86.8%, 77.8%, and 86.0%, respectively. 92.3% of local relapses and 86.0% of regional relapses occurred within the 95% isodose lines and were considered GTV in-field failures. No significant differences in DVH parameters were observed between the local relapse group and the propensity score-matched non-relapse group. Compared with the 2018-IG, our contouring protocol resulted in a 58.4% and 48.3% reduction in PTV70, and an 80.8% and 62.8% reduction in PTV60 for early and advanced-stage disease, respectively. Late grade 3 toxicities included ototoxicity (1.8%), xerostomia (0.2%), dysphagia (0.2%), temporal lobe injury (0.2%), and trismus (0.1%). Individualized elective CTVp delineation based on the stepwise spread patterns of nasopharyngeal carcinoma achieved excellent long-term outcomes and reduced the irradiated volumes at equivalent dose levels compared to the 2018-IG.

Delineation Protocol of Agricultural Management Zones (Olive Trees and Alfalfa) at Field Scale (Crete, Greece)

This study proposes a three-stage, flexible and adaptable protocol for the establishment of field-scale agricultural management zones (AMZs) using remote sensing, ground truthing (apparent electrical conductivity and soil sampling), the IRRIGOPTIMAL® system and machine learning. The methodology to develop this protocol was applied to olive and alfalfa plots in Heraklion (Crete, Greece) to monitor soil and plant responses for the period 2022–2024. However, the actual time for the implementation of this protocol varies between 3 and 6 months. The first step of this protocol involves the use of soil and vegetation reflectance mapping (moisture, photosynthetic activity) by satellites and unmanned aerial systems, together with geophysical electromagnetic induction mapping (apparent electrical conductivity) to verify soil variability, which is strongly linked to the delineation of management zones. In the second step, a machine learning-based prediction of the spatial distribution of soil electrical conductivity is made, considering the data obtained in the first step. Furthermore, in the second step, the IRRIGOPTIMAL® system provides real-time monitoring of a variety of weather (such as air temperature, dew point, solar radiation, relative humidity, precipitation) and soil (temperature, moisture) parameters to support the optimal cultivation strategy for the plants. Once the data have been analysed, the soil variability of the plot and the presence or absence of cultivation zones are determined and the decision on the cultivation strategy is made based on targeted soil sampling and further soil analyses. This protocol could contribute significantly to the rational use of inputs (water, seeds, fertilizers and pesticides) and support variable rate technology in the agricultural sector of Crete.

The individualized delineation of clinical target volume for primary nasopharyngeal carcinoma based on invasion risk of substructures: A prospective, real-world study with a large population

Background and purposeThe delineation of clinical target volume (CTV) for primary nasopharyngeal carcinoma (NPC) is currently controversial and the international guideline still recommend a uniform border for CTV regardless of the tumor extent. We conducted this prospective, real-world study to evaluate the clinical outcomes of our individualized CTV delineation method based on distance plus substructures. Materials and MethodsWe preliminarily investigated the local extension patterns of NPC on 354 newly diagnosed patients and defined the structures surrounding the nasopharynx as Level-1 to Level-4 substructures stratified by the risk of invasion. We then enrolled patients with newly diagnosed NPC without distant metastasis to investigate our individualized CTV delineation protocol. All patients received intensity modulated radiotherapy. CTV1 and CTV2 were prescribed doses of 60 Gy and 54 Gy in 30 ∼ 33 fractions. The primary endpoint was local recurrence-free survival (LRFS); secondary endpoints included regional control and survival, estimated using the Kaplan-Meier method. The local failure patterns were also analyzed. ResultsFrom January 2008 to December 2012 and from January 2013 to September 2019, 356 and 648 patients were enrolled, named as training set and validation set, respectively. With a median follow-up of 104.6 (interquartile, 73.1–126.9) and 51.4 (39.5–78.5) months, 31 (8.7 %) and 38 (5.9 %) patients in training and validation sets experienced local recurrence, and the 5-year LRFS was 93.0 % and 93.2 %, respectively; 63 (17.7 %) and 39 (6 %) patients died in training and validation sets, and the 5-year overall survival (OS) was 88.5 % and 93.4 %, respectively. For the whole study cohort (N = 1004) with a median follow-up of 66.6 (41.5–98.0) months, the 5-year LRFS and OS was 93.2 % and 91.5 %. The grade 3 late toxicities included xerostomia, subcutaneous fibrosis, hearing impairment, trismus, visuality impairment and skin atrophy, with a total incidence of 1.5 %. Sixty-seven of 69 (97.1 %) local recurrence was in high-dose area. ConclusionOur individualized CTV delineation method can achieve favorable local tumor control and long-term survival outcomes with acceptable late toxicities.

Implementing the QUALI-DEC project in Argentina, Burkina Faso, Thailand and Viet Nam: a process delineation and theory-driven process evaluation protocol

ABSTRACT The project ‘Quality Decision-making by women and providers’ (QUALI-DEC) combines four non-clinical interventions to promote informed decision-making surrounding mode of birth, improve women’s birth experiences, and reduce caesarean sections among low-risk women. QUALI-DEC is currently being implemented in 32 healthcare facilities across Argentina, Burkina Faso, Thailand, and Viet Nam. In this paper, we detail implementation processes and the planned process evaluation, which aims to assess how and for whom QUALI-DEC worked, the mechanisms of change and their interactions with context and setting; adaptations to intervention and implementation strategies, feasibility of scaling-up, and cost-effectiveness of the intervention. We developed a project theory of change illustrating how QUALI-DEC might lead to impact. The theory of change, together with on the ground observations of implementation processes, guided the process evaluation strategy including what research questions and perspectives to prioritise. Main data sources will include: 1) regular monitoring visits in healthcare facilities, 2) quantitative process and output indicators, 3) a before and after cross-sectional survey among post-partum women, 4) qualitative interviews with all opinion leaders, and 5) qualitative interviews with postpartum women and health workers in two healthcare facilities per country, as part of a case study approach. We foresee that the QUALI-DEC process evaluation will generate valuable information that will improve interpretation of the effectiveness evaluation. At the policy level, we anticipate that important lessons and methodological insights will be drawn, with application to other settings and stakeholders looking to implement complex interventions aiming to improve maternal and newborn health and wellbeing. Trial registration: ISRCTN67214403.

Long-Term Outcome Following Intensity-Modulated Radiotherapy Delivered Using Individualized Clinical Target Volume Delineation Based on Stepwise Spread Pattern of Nasopharyngeal Carcinoma

<h3>Purpose/Objective(s)</h3> The optimal method for clinical target volume delineation in nasopharyngeal carcinoma has not yet been determined. We have developed an individualized CTV delineation protocol based on the stepwise spread patterns of NPC. This study aimed to determine the long-term outcomes and toxicities in NPC patients receiving intensity-modulated radiotherapy with individualized CTV delineation. <h3>Materials/Methods</h3> We retrospectively reviewed the data of patients with newly diagnosed nondisseminated NPC who underwent IMRT using our individualized CTV delineation protocol. A total of 7,262 patients with NPC (79.3% patients in stage III-IVA) treated between April 2009 and December 2015 were included in this study. Dose–volume statistics, clinical outcomes, patterns of failures and toxicities were assessed. To analyze dose distribution of patients with or without local recurrence, propensity score matching (PSM) was performed to compare the dose between the two groups matched by age, sex, histological type, T category, N category, chemotherapy and gross tumor volume of primary tumor and enlarged retropharyngeal lymph nodes (GTVnx) in a 1:1 ratio. <h3>Results</h3> Median follow-up was 67.3 (range, 2.0-118.7) months. The 5-year local relapse–free survival, regional relapse–free survival, distant metastasis–free survival, progression–free survival, and overall survival rates were 93.6%, 94.4%, 86.8%, 77.8%, and 86.0%, respectively. In-field failure is the major locoregional failure pattern, accounting for 92.3% patients of local and 86% of regional recurrence. Age and T classification were independent prognostic for LRFS, DMFS, PFS, and OS in multivariate analysis. Late grade 3 toxicities were mild and included ear injury (1.8%), xerostomia (0.2%), dysphagia (0.2%), brain injury (0.2%), and trismus (0.1%). No grade 4 toxicity occurred during IMRT or follow-up. PSM analysis revealed no significant difference between minimum (P = 0.815), maximum (P = 0.595), and mean (P = 0.700) dose to the planning tumor volume of primary tumor and enlarged retropharyngeal lymph nodes (PTVnx) between patients with local recurrence and the matched patients without local recurrence. <h3>Conclusion</h3> Our stepwise CTV delineation protocol appears to be a promising strategy for improving outcomes in NPC.

Can the Choice of Radiotherapy Delivery Technique Influence Which Target Delineation Protocol to Use? A Plan-Quality-Based Analysis in Left Breast Cancer

Introduction This study investigates the optimal target delineation protocol stratified by treatment planning technique in patients undergoing whole breast radiotherapy after breast conservation surgery. Materials and Methods Target delineation using Tangent (RTOG 0413 Whole Breast Irradiation Protocol), European SocieTy for Radiotherapy and Oncology (ESTRO), and Radiation Therapy &amp; Oncology Group (RTOG) guidelines was performed on 10 randomly selected treatment planning computed tomography datasets of patients with left-sided breast cancer. An objective plan quality metric (PQM) scoring schema was defined and communicated to the medical physicist prior to commencement of treatment planning. Treatment planning was performed using field-in-field (FiF) intensity modulated radiotherapy technique (IMRT), inverse IMRT, and volumetric modulated arc therapy (VMAT), for each type of target. Two-way repeated measures, analysis of variance was utilized to compare the total PQM scores and dosimetric variables, stratified by treatment planning method. Results Total PQM score of plans for FiF, IMRT, and VMAT revealed that Tangent and ESTRO delineations were equivalent regardless of planning technique (Tangent vs. ESTRO for FiF, p = 0.099; Tangent vs. ESTRO for IMRT, p = 0.029; Tangent vs. ESTRO for VMAT, p = 0.438). Both delineation protocols were significantly superior to RTOG for all treatment planning techniques. Conclusion For all treatment planning techniques, ESTRO and Tangent delineation were equivalent and both achieved significantly higher scores than RTOG delineation.

PO-1037: A new nodal delineation protocol for upper third oesophageal cancers in the SCOPE 2 trial

PO-1037: A new nodal delineation protocol for upper third oesophageal cancers in the SCOPE 2 trial

Preliminary Validation of an IMRT Target Volume Delineation Protocol for Patients with Locally Advanced Gastric Cancer Receiving Preoperative Chemoradiation in Comparison with Preoperative Chemotherapy

Preliminary Validation of an IMRT Target Volume Delineation Protocol for Patients with Locally Advanced Gastric Cancer Receiving Preoperative Chemoradiation in Comparison with Preoperative Chemotherapy

Multiple training interventions significantly improve reproducibility of PET/CT-based lung cancer radiotherapy target volume delineation using an IAEA study protocol

Background and purposeTo assess the impact of a standardized delineation protocol and training interventions on PET/CT-based target volume delineation (TVD) in NSCLC in a multicenter setting. Material and methodsOver a one-year period, 11 pairs, comprised each of a radiation oncologist and nuclear medicine physician with limited experience in PET/CT-based TVD for NSCLC from nine different countries took part in a training program through an International Atomic Energy Agency (IAEA) study (NCT02247713). Teams delineated gross tumor volume of the primary tumor, during and after training interventions, according to a provided delineation protocol. In-house developed software recorded the performed delineations, to allow visual inspection of strategies and to assess delineation accuracy. ResultsFollowing the first training, overall concordance indices for 3 repetitive cases increased from 0.57±0.07 to 0.66±0.07. The overall mean surface distance between observer and expert contours decreased from −0.40±0.03cm to −0.01±0.33cm. After further training overall concordance indices for another 3 repetitive cases further increased from 0.64±0.06 to 0.80±0.05 (p=0.01). Mean surface distances decreased from −0.34±0.16cm to −0.05±0.20cm (p=0.01). ConclusionMultiple training interventions improve PET/CT-based TVD delineation accuracy in NSCLC and reduce interobserver variation.

Taxonomic revision of the Malagasy Nesomyrmex madecassus species-group using a quantitative morphometric approach.

Here we reveal the diversity of the next fragment of the Malagasy elements of the ant genus Nesomyrmex using a combination of advanced exploratory analyses on quantitative morphological data. The diversity of the Nesomyrmex madecassus species-group was assessed via hypothesis-free nest centroid clustering combined with recursive partitioning to estimate the number of clusters and determine the most probable boundaries between them. This combination of methods provides a highly automated species delineation protocol based on continuous morphometric data, and thereby it obviates the need of subjective interpretation of morphological patterns. Delimitations of clusters recognized by these exploratory analyses were tested via confirmatory Linear Discriminant Analysis (LDA). Our results suggest the existence of four morphologically distinct species, Nesomyrmex flavus sp. n., Nesomyrmex gibber, Nesomyrmex madecassus and Nesomyrmex nitidus sp. n.; all are described here and an identification key for their worker castes using morphometric data is given. Two members of the newly outlined madecasus species-group, Nesomyrmex flavus sp. n. and Nesomyrmex nitidus sp. n., represent true cryptic species. Geographic maps depicting species distributions and elevational information for the sites where populations of particular species were collected are also provided.

Recurrence patterns in patients with high-grade glioma following temozolomide-based chemoradiotherapy.

There is currently no consensus regarding the optimal radiation volume for high-grade glioma (HGG). The brain volume irradiated is associated with the extent of radiation neurotoxicity. When reducing the treatment volume, the risk of geographic tumor miss should be considered. In such cases, the recurrence patterns and, particularly, the rate of marginal tumor recurrence, are important indices for determining the optimal radiation volume. In the present study, a smaller-target delineation protocol with limited margins was adopted. The postoperative enhancing tumor and resection cavity were defined as gross tumor volume (GTV); 1 and 2 cm were added to the GTV to create clinical target volume (CTV1 and CTV2), which received 60 and 54 Gy, respectively. At a median follow-up of 14 months, 54 HGG patients developed tumor recurrence. The median overall and progression-free survival were 14 and 10.5 months, respectively. A total of 34 patients developed central recurrence, 8 presented with in-field recurrence, 2 developed marginal recurrence, 2 had distant recurrence and 11 patients developed cerebrospinal fluid dissemination, 2 of whom developed central recurrence, with 1 patient simultaneously developing marginal recurrence. Local recurrence (central and in-field) was found to be the main recurrence pattern. As the rate of marginal recurrence was low (<5%), it appears that the smaller irradiated volume in the present study was appropriate. However, clinical trials investigating limited irradiation volume are required to validate our findings.

SU-F-R-21: The Stability of Radiomics Features On 4D FDG-PET/CT Images

Purpose: The aim of our study was to perform a stability analysis of 4D PET-derived features in non-small cell lung carcinoma (NSCLC) based on six different respiratory phases. Methods: The 4D FDG-PET/CT respiratory phases were labeled as T0%, T17%, T33%,T50%, T67%, T83% phases, with the T0% phase approximately corresponding to the normal end-inspiration. Lesions were manually delineated based on fused PET-CT, using a standardized clinical delineation protocol. Six texture parameters were analyzed. Results: Results showed that the majority of assessed features had a low stability such as Homogeneity (0.385–0.416), Dissimilarity (3.707–3.861), Angular two moments (0.013–0.019), Contrast (39.782–49.562), Entropy(4.683–5.002) and Inverse differential moment (0.317–0.362) on different respiratory phases. Conclusion: This study suggest that further research of quantitative PET imaging features is warranted with respect to respiratory motion.

Toward Objective, Morphology-Based Taxonomy: A Case Study on the Malagasy Nesomyrmex sikorai Species Group (Hymenoptera: Formicidae).

Madagascar is one of the world’s greatest biodiversity hotspots, meriting special attention from biodiversity scientists. It is an excellent testing ground for novel techniques in taxonomy that aim to increase classification objectivity and yield greater taxonomic resolving power. Here we reveal the diversity of a unique and largely unexplored fragment of the Malagasy ant fauna using an advanced combination of exploratory analyses on quantitative morphological data allowing for increased objectivity in taxonomic workflow. The diversity of the Nesomyrmex sikorai species-group was assessed via hypothesis-free nest-centroid-clustering combined with recursive partitioning to estimate the number of morphological clusters and determine the most probable boundaries between them. This combination of methods provides a highly automated and objective species delineation protocol based on continuous morphometric data. Delimitations of clusters recognized by these exploratory analyses were tested via confirmatory Linear Discriminant Analysis (LDA) and Multivariate Ratio Analysis (MRA). The final species hypotheses are corroborated by many qualitative characters, and the recognized species exhibit different spatial distributions and occupy different ecological regions. We describe and redescribe eight morphologically distinct species including six new species: Nesomyrmex excelsior sp. n., N. modestus sp. n., N. reticulatus sp. n., N. retusispinosus (Forel, 1892), N. rugosus sp. n., N. sikorai (Emery, 1896), N. striatus sp. n., and N. tamatavensis sp. n. An identification key for their worker castes using morphometric data is provided.

The efficacy and toxicity of individualized intensity-modulated radiotherapy based on the tumor extension patterns of nasopharyngeal carcinoma.

BackgroundTo evaluate the efficacy and toxicity of intensity-modulated radiotherapy (IMRT) using individualized clinical target volumes (CTVs) based on the loco-regional extension patterns of nasopharyngeal carcinoma (NPC).MethodsFrom December 2009 to February 2012, 220 patients with histologically-proven, non-disseminated NPC were prospectively treated with IMRT according to an individualized delineation protocol. CTV1 encompassed the gross tumor volume, entire nasopharyngeal mucosa and structures within the pharyngobasilar fascia with a margin. CTV2 encompassed bilateral high risk anatomic sites and downstream anatomic sites adjacent to primary tumor, bilateral retropharyngeal regions, levels II, III and Va, and prophylactic irradiation was gave to one or two levels beyond clinical lymph nodes involvement. Clinical outcomes and toxicities were evaluated.ResultsMedian follow-up was 50.8 (range, 1.3–68.0) months, four-year local relapse-free, regional relapse-free, distant metastasis-free, disease-free and overall survival rates were 94.7%, 97.0%, 91.7%, 87.2% and 91.9%, respectively. Acute severe (≥ grade 3) mucositis, dermatitis and xerostomia were observed in 27.6%, 3.6% and zero patients, respectively. At 1 year, xerostomia was mild, with frequencies of Grade 0, 1, 2 and 3 xerostomia of 27.9%, 63.3%, 8.3% and 0.5%, respectively.ConclusionsIMRT using individualized CTVs provided high rates of local and regional control and a favorable toxicity profile in NPC. Individualized CTV delineation strategy is a promising one that may effectively avoid unnecessary or missed irradiation, and deserve optimization to define more precise individualized CTVs.

135 Multiple training interventions significantly improves PET/CT based lung cancer radiotherapy target volume delineation following an IAEA based delineation protocol

135 Multiple training interventions significantly improves PET/CT based lung cancer radiotherapy target volume delineation following an IAEA based delineation protocol

Interobserver Variations of Clinical Target Volume Delineation in External Beam Radiation Therapy of Pancreatic Cancer: Impact of Multi-institutional Delineation Protocol

Interobserver Variations of Clinical Target Volume Delineation in External Beam Radiation Therapy of Pancreatic Cancer: Impact of Multi-institutional Delineation Protocol

Diagnostic survey of Malagasy Nesomyrmex species-groups and revision of hafahafa group species via morphology based cluster delimitation protocol.

Madagascar and its surrounding islands are among the world’s greatest biodiversity hotspots, harboring predominantly endemic and threatened communities meriting special attention from biodiversity scientists. Building on the considerable efforts in recent years to inventory the Malagasy ant fauna, the myrmicine genus Nesomyrmex is reviewed and (1) subdivided into four major groups based on salient morphological features corroborated by numeric morphology: angulatus-, hafahafa-, madecassus- and sikorai-groups, and (2) the hafahafa species-group endemic to Madagascar is revised. Diversity within hafahafa species-group was assessed via hypothesis-free nest-centroid-clustering combined with gap statistic to assess the number of clusters and to determine the most probable boundaries between them. This combination of methods provides a highly automatized, objective species delineation protocol based on continuous morphometric data. Delimitations of clusters recognized by these exploratory analyses were tested via confirmatory Linear Discriminant Analysis. These results suggest the existence of four morphologically distinct species, Nesomyrmex capricornis sp. n., Nesomyrmex hafahafa sp. n., Nesomyrmex medusus sp. n. and Nesomyrmex spinosus sp. n.; all are described and an identification key for their worker castes using morphometric data is provided. Two members of the newly outlined hafahafa species-group, Nesomyrmex hafahafa sp. n., Nesomyrmex medusus sp. n., are distributed along the southeastern coast Madagascar and occupy rather large ranges, but two other species, Nesomyrmex capricornis sp. n. and Nesomyrmex spinosus sp. n., are only known to occur in small and isolated forest, highlighting the importance of small forest patches for conserving arthropod diversity.

A clip-based protocol for breast boost radiotherapy provides clear target visualisation and demonstrates significant volume reduction over time.

IntroductionThe clinical target volume (CTV) for early stage breast cancer is difficult to clearly identify on planning computed tomography (CT) scans. Surgical clips inserted around the tumour bed should help to identify the CTV, particularly if the seroma has been reabsorbed, and enable tracking of CTV changes over time.MethodsA surgical clip-based CTV delineation protocol was introduced. CTV visibility and its post-operative shrinkage pattern were assessed. The subjects were 27 early stage breast cancer patients receiving post-operative radiotherapy alone and 15 receiving post-operative chemotherapy followed by radiotherapy. The radiotherapy alone (RT/alone) group received a CT scan at median 25 days post-operatively (CT1rt) and another at 40 Gy, median 68 days (CT2rt). The chemotherapy/RT group (chemo/RT) received a CT scan at median 18 days post-operatively (CT1ch), a planning CT scan at median 126 days (CT2ch), and another at 40 Gy (CT3ch).ResultsThere was no significant difference (P = 0.08) between the initial mean CTV for each cohort. The RT/alone cohort showed significant CTV volume reduction of 38.4% (P = 0.01) at 40 Gy. The Chemo/RT cohort had significantly reduced volumes between CT1ch: median 54 cm3 (4–118) and CT2ch: median 16 cm3, (2–99), (P = 0.01), but no significant volume reduction thereafter.ConclusionSurgical clips enable localisation of the post-surgical seroma for radiotherapy targeting. Most seroma shrinkage occurs early, enabling CT treatment planning to take place at 7 weeks, which is within the 9 weeks recommended to limit disease recurrence.

An algorithm for optimal fusion of atlases with different labeling protocols

In this paper we present a novel label fusion algorithm suited for scenarios in which different manual delineation protocols with potentially disparate structures have been used to annotate the training scans (hereafter referred to as “atlases”). Such scenarios arise when atlases have missing structures, when they have been labeled with different levels of detail, or when they have been taken from different heterogeneous databases. The proposed algorithm can be used to automatically label a novel scan with any of the protocols from the training data. Further, it enables us to generate new labels that are not present in any delineation protocol by defining intersections on the underling labels. We first use probabilistic models of label fusion to generalize three popular label fusion techniques to the multi-protocol setting: majority voting, semi-locally weighted voting and STAPLE. Then, we identify some shortcomings of the generalized methods, namely the inability to produce meaningful posterior probabilities for the different labels (majority voting, semi-locally weighted voting) and to exploit the similarities between the atlases (all three methods). Finally, we propose a novel generative label fusion model that can overcome these drawbacks. We use the proposed method to combine four brain MRI datasets labeled with different protocols (with a total of 102 unique labeled structures) to produce segmentations of 148 brain regions. Using cross-validation, we show that the proposed algorithm outperforms the generalizations of majority voting, semi-locally weighted voting and STAPLE (mean Dice score 83%, vs. 77%, 80% and 79%, respectively). We also evaluated the proposed algorithm in an aging study, successfully reproducing some well-known results in cortical and subcortical structures.

Comparison of human septal nuclei MRI measurements using automated segmentation and a new manual protocol based on histology

Septal nuclei, located in basal forebrain, are strongly connected with hippocampi and important in learning and memory, but have received limited research attention in human MRI studies. While probabilistic maps for estimating septal volume on MRI are now available, they have not been independently validated against manual tracing of MRI, typically considered the gold standard for delineating brain structures. We developed a protocol for manual tracing of the human septal region on MRI based on examination of neuroanatomical specimens. We applied this tracing protocol to T1 MRI scans (n=86) from subjects with temporal epilepsy and healthy controls to measure septal volume. To assess the inter-rater reliability of the protocol, a second tracer used the same protocol on 20 scans that were randomly selected from the 72 healthy controls. In addition to measuring septal volume, maximum septal thickness between the ventricles was measured and recorded. The same scans (n=86) were also analyzed using septal probabilistic maps and DARTEL toolbox in SPM. Results show that our manual tracing algorithm is reliable, and that septal volume measurements obtained via manual and automated methods correlate significantly with each other (p<.001). Both manual and automated methods detected significantly enlarged septal nuclei in patients with temporal lobe epilepsy in accord with a proposed compensatory neuroplastic process related to the strong connections between septal nuclei and hippocampi. Septal thickness, which was simple to measure with excellent inter-rater reliability, correlated well with both manual and automated septal volume, suggesting it could serve as an easy-to-measure surrogate for septal volume in future studies. Our results call attention to the important though understudied human septal region, confirm its enlargement in temporal lobe epilepsy, and provide a reliable new manual delineation protocol that will facilitate continued study of this critical region.