Tag: Volume

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Navigated intraoperative ultrasound in neuro-oncology: volumetric accuracy and correlation with high-field MRI

J Neurosurg 141:79–88, 2024

The use of intraoperative techniques to detect residual tumors has recently become increasingly important. Intraoperative MRI has long been considered the gold standard; however, it is not widely used because of high equipment costs and long acquisition times. Consequently, real-time intraoperative ultrasound (ioUS), which is much less expensive than MRI, has gained popularity. The aim of the present study was to evaluate the capacity of ioUS to accurately determine the primary tumor volume and detect residual tumors.

METHODS A prospective study of adult patients who underwent surgery for intra-axial brain tumors between November 2017 and October 2020 was performed. Navigated intraoperative ultrasound (nioUS) of the brain was used to guide tumor resection and to detect the presence of residual disease. Both convex (5–8 MHz) and linear array (6–13 MHz) probes were used. Tumor volume and residual disease were measured with nioUS and compared with MR images. A linear regression model based on a machine learning pipeline and a Bland-Altman analysis were used to assess the accuracy of nioUS versus MRI.

RESULTS Eighty patients (35 females and 45 males) were included. The mean age was 58 years (range 25–80 years). A total of 88 lesions were evaluated; there were 64 (73%) gliomas, 19 (21.6%) metastases, and 5 (5.7%) other tumors, mostly located in the frontal (41%) and temporal (27%) lobes. Most of the tumors (75%) were perfectly visible on ioUS (grade 3, Mair grading system), except for those located in the insular lobe (grade 2). The regression model showed a nearly perfect correlation (R 2 = 0.97, p < 0.001) between preoperative tumor volumes from both MRI and nioUS. Ultrasonographic visibility significantly influenced this correlation, which was stronger for highly visible (grade 3) tumors (p = 0.01). For residual tumors, the correlation between postoperative MRI and nioUS was weaker (R 2 = 0.78, p < 0.001) but statistically significant. The Bland-Altman analysis showed minimal bias between the two techniques for pre- and postoperative scenarios, with statistically significant results for the preoperative concordance.

CONCLUSIONS The authors’ findings show that most brain tumors are well delineated by nioUS and almost perfectly correlated with MRI-based measurements both pre- and postoperatively. These data support the hypothesis that nioUS is a reliable intraoperative technique that can be used for real-time monitoring of brain tumor resections and to perform volumetric analysis of residual disease.

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Volumetric Growth and Growth Curve Analysis of Residual Intracranial Meningioma

Neurosurgery 92:734–744, 2023

After meningioma surgery, approximately 1 in 3 patients will have residual tumor that requires ongoing imaging surveillance. The precise volumetric growth rates of these tumors are unknown.

OBJECTIVE: To identify the volumetric growth rates of residual meningioma, growth trajectory, and factors associated with progression.

METHODS: Patients with residual meningioma identified at a tertiary neurosurgery center between 2004 and 2020 were retrospectively reviewed. Tumor volumewas measured using manual segmentation, after surgery and at every follow-up MRI scan. Growth rates were ascertained using a linear mixed-effects model and nonlinear regression analysis of growth trajectories. Progression was defined according to the Response Assessment in Neuro- Oncology (RANO) criteria (40% volume increase).

RESULTS: There were 236 patients with residual meningioma. One hundred and thirtytwo patients (56.0%) progressed according to the RANO criteria, with 86 patients being conservatively managed (65.2%) after progression. Thirteen patients (5.5%) developed clinical progression. Over a median follow-up of 5.3 years (interquartile range, 3.5–8.6 years), the absolute growth rate was 0.11 cm3 per year and the relative growth rate 4.3% per year. Factors associated with residual meningioma progression in multivariable Cox regression analysis were skull base location (hazard ratio [HR] 1.60, 95% CI 1.02–2.50) and increasing Ki-67 index (HR 3.43, 95% CI 1.19–9.90). Most meningioma exhibited exponential and logistic growth patterns (median R2 value 0.84, 95% CI 0.60–0.90).

CONCLUSION: Absolute and relative growth rates of residual meningioma are low, but most meet the RANO criteria for progression. Location and Ki-67 index can be used to stratify adjuvant treatment and surveillance paradigms.

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Intracerebral Hemorrhage Volume Reduction and Timing of Intervention Versus Functional Benefit and Survival in the MISTIE III and STICH Trials

Neurosurgery 88:961–970, 2021

The extent of intracerebral hemorrhage (ICH) removal conferred survival and functional benefits in the minimally invasive surgery with thrombolysis in intracerebral hemorrhage evacuation (MISTIE) III trial. It is unclear whether this similarly impacts outcome with craniotomy (open surgery) or whether timing from ictus to intervention influences outcome with either procedure.

OBJECTIVE: To compare volume evacuation and timing of surgery in relation to outcomes in the MISTIE III and STICH (Surgical Trial in Intracerebral Hemorrhage) trials.

METHODS: Postoperative scans were performed in STICH II, but not in STICH I; therefore, surgical MISTIE III cases with lobar hemorrhages (n = 84) were compared to STICH II all lobar cases (n = 259) for volumetric analyses. All MISTIE III surgical patients (n = 240) were compared to both STICH I and II (n = 722) surgical patients for timing analyses. These were investigated using cubic spline modeling and multivariate risk adjustment.

RESULTS: End-of-treatment ICH volume≤28.8mLin MISTIE III and≤30.0mLin STICH II had increased probability of modified Rankin Scale (mRS) 0 to 3 at 180 d (P = .01 and P = .003, respectively). The effect in the MISTIE cohort remained significant after multivariate risk adjustments. Earlier surgery within 62 h of ictus had a lower probability of achieving an mRS 0 to 3 at 180 d with STICH I and II (P = .0004), but not with MISTIE III. This remained significant with multivariate risk adjustments. There was no impact of timing until intervention on mortality up to 47 h with either procedure.

CONCLUSION: Thresholds of ICH removal influenced outcome with both procedures to a similar extent. There was a similar likelihood of achieving a good outcome with both procedures within a broad therapeutic time window.

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Global hydrocephalus epidemiology and incidence: systematic review and meta-analysis

J Neurosurg 130:1065–1079, 2019

Hydrocephalus is one of the most common brain disorders, yet a reliable assessment of the global burden of disease is lacking. The authors sought a reliable estimate of the prevalence and annual incidence of hydrocephalus worldwide.

METHODS The authors performed a systematic literature review and meta-analysis to estimate the incidence of congenital hydrocephalus by WHO region and World Bank income level using the MEDLINE/PubMed and Cochrane Database of Systematic Reviews databases. A global estimate of pediatric hydrocephalus was obtained by adding acquired forms of childhood hydrocephalus to the baseline congenital figures using neural tube defect (NTD) registry data and known proportions of posthemorrhagic and postinfectious cases. Adult forms of hydrocephalus were also examined qualitatively.

RESULTS Seventy-eight articles were included from the systematic review, representative of all WHO regions and each income level. The pooled incidence of congenital hydrocephalus was highest in Africa and Latin America (145 and 316 per 100,000 births, respectively) and lowest in the United States/Canada (68 per 100,000 births) (p for interaction < 0.1). The incidence was higher in low- and middle-income countries (123 per 100,000 births; 95% CI 98–152 births) than in high-income countries (79 per 100,000 births; 95% CI 68–90 births) (p for interaction < 0.01). While likely representing an underestimate, this model predicts that each year, nearly 400,000 new cases of pediatric hydrocephalus will develop worldwide. The greatest burden of disease falls on the African, Latin American, and Southeast Asian regions, accounting for three-quarters of the total volume of new cases. The high crude birth rate, greater proportion of patients with postinfectious etiology, and higher incidence of NTDs all contribute to a case volume in low- and middle-income countries that outweighs that in high-income countries by more than 20-fold. Global estimates of adult and other forms of acquired hydrocephalus are lacking.

CONCLUSIONS For the first time in a global model, the annual incidence of pediatric hydrocephalus is estimated. Low and middle-income countries incur the greatest burden of disease, particularly those within the African and Latin American regions. Reliable incidence and burden figures for adult forms of hydrocephalus are absent in the literature and warrant specific investigation. A global effort to address hydrocephalus in regions with the greatest demand is imperative to reduce disease incidence, morbidity, mortality, and disparities of access to treatment.

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Volumetric CT analysis as a predictor of seizure outcome following temporal lobectomy

Volumetric brain analysis in neurosurgery- Part 3

J Neurosurg Pediatr 15:133–143, 2015

The incidence of temporal lobe epilepsy (TLE) due to mesial temporal sclerosis (MTS) can be high in developing countries. Current diagnosis of MTS relies on structural MRI, which is generally unavailable in developing world settings. Given widespread effects on temporal lobe structure beyond hippocampal atrophy in TLE, the authors propose that CT volumetric analysis can be used in patient selection to help predict outcomes following resection.

METHODS Ten pediatric patients received preoperative CT scans and temporal resections at the CURE Children’s Hospital of Uganda. Engel classification of seizure control was determined 12 months postoperatively. Temporal lobe volumes were measured from CT and from normative MR images using the Cavalieri method. Whole brain and fluid volumes were measured using particle filter segmentation. Linear discrimination analysis (LDA) was used to classify seizure outcome by temporal lobe volumes and normalized brain volume.

RESULTS Epilepsy patients showed normal to small brain volumes and small temporal lobes bilaterally. A multivariate measure of the volume of each temporal lobe separated patients who were seizure free (Engel Class IA) from those with incomplete seizure control (Engel Class IB/IIB) with LDA (p < 0.01). Temporal lobe volumes also separate normal subjects, patients with Engel Class IA outcomes, and patients with Class IB/IIB outcomes (p < 0.01). Additionally, the authors demonstrated that age-normalized whole brain volume, in combination with temporal lobe volumes, may further improve outcome prediction (p < 0.01).

CONCLUSIONS This study shows strong evidence that temporal lobe and brain volume can be predictive of seizure outcome following temporal lobe resection, and that volumetric CT analysis of the temporal lobe may be feasible in lieu of structural MRI when the latter is unavailable. Furthermore, since the authors’ methods are modality independent, these findings suggest that temporal lobe and normative brain volumes may further be useful in the selection of patients for temporal lobe resection when structural MRI is available.

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Trigeminal nerve atrophy caused by neurovascular compression

Atrophic changes in the trigeminal nerves of patients with trigeminal neuralgia due to neurovascular compression and their association with the severity of compression and clinical outcomes

J Neurosurg 120:1484–1495, 2014

The aim of this study was to prospectively evaluate atrophic changes in trigeminal nerves (TGNs) using measurements of volume (V) and cross-sectional area (CSA) from high-resolution 3-T MR images obtained in patients with unilateral trigeminal neuralgia (TN), and to correlate these data with patient and neurovascular compression (NVC) characteristics and with clinical outcomes.

Methods. Anatomical TGN parameters (V and CSA) were obtained in 50 patients (30 women and 20 men; mean age 56.42 years, range 22–79 years) with classic TN before treatment with microvascular decompression (MVD). Parameters were compared between the symptomatic (ipsilateralTN) and asymptomatic (contralateralTN) sides of the face. Twenty normal control subjects were also included. Two independent observers blinded to the side of pain separately analyzed the images. Measurements of V (from the pons to the entrance of the nerve into Meckel’s cave) and CSA (at 5 mm from the entry of the TGN into the pons) for each TGN were performed using imaging software and axial and coronal projections, respectively. These data were correlated with patient characteristics (age, duration of symptoms before MVD, side of pain, sex, and area of pain distribution), NVC characteristics (type of vessel involved in NVC, location of compression along the nerve, site of compression around the circumference of the root, and degree of compression), and clinical outcomes at the 2-year follow-up after surgery. Comparisons were made using Bonferroni’s test. Interobserver variability was assessed using the Pearson correlation coefficient.

Results. The mean V of the TGN on the ipsilateralTN (60.35 ± 21.74 mm3) was significantly smaller (p < 0.05) than those for the contralateralTN and controls (78.62 ± 24.62 mm3 and 89.09 ± 14.72 mm3, respectively). The mean CSA of the TGN on the ipsilateralTN (4.17 ± 1.74 mm2) was significantly smaller than those for the contralateralTN and controls (5.41 ± 1.89 mm2 and 5.64 ± 0.85 mm2, respectively). The ipsilateralTN with NVC Grade III (marked indentation) had a significantly smaller mean V than the ipsilateralTN with NVC Grade I (mere contact), although it was not significantly smaller than that of the ipsilateralTN with NVC Grade II (displacement or distortion of root). The ipsilateralTN with NVC Grade III had a significantly smaller mean CSA than the ipsilateral TN with NVC Grades I and II (p < 0.05). The TGN on the ipsilateralTN in cured patients had a smaller mean CSA than that on the ipsilateralTN of patients with partial pain relief or treatment failure (p < 0.05). The same finding was almost found in relation to measurements of V, but the p value was slightly higher at 0.05.

Conclusions. Results showed that TGN atrophy in patients with TN can be demonstrated by high-resolution imaging. These data suggest that atrophic changes in TGNs, which significantly correlated with the severity of compression and clinical outcomes, may help to predict long-term prognosis after vascular decompression.

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Comparative Morphological Analysis of the Geometry of Ruptured and Unruptured Aneurysms

Neurosurgery 69:349–356, 2011 DOI: 10.1227/NEU.0b013e31821661c3

The risk of aneurysm rupture appears to be related to multiple factors such as topology, morphology, size, perianeurysmal environment, and blood flow hemodynamics.

OBJECTIVE: To evaluate aneurysm morphology and to quantitatively compare the volumetric parameters between ruptured and unruptured aneurysms from our clinical database at the UCLA Medical Center.

METHODS: Novel algorithms that automatically compute aneurysm geometry were tested on the basis of voxel data obtained from angiographic images, and measurements of aneurysm morphology were automatically recorded. We studied a total of 50 aneurysms (25 ruptured and 25 unruptured) with sizes ranging from 3 to 26 mm. To compare the geometric characteristics between ruptured and unruptured groups, we examined measurements, including volume and surface area, and the ratios of these measurements to the minimal bounding sphere around each aneurysm.

RESULTS: More than 65% of ruptured aneurysms had a ratio of aneurysm volume to bounding sphere volume (AVSV) of > 0.5. More than 70% of ruptured aneurysms had a ratio of aneurysm surface to bounding sphere surface (AASA) of < 1. A trend differentiating ruptured and unruptured aneurysms was observed in AVSV (P = .07) and AASA (P = .04). Classification and regression trees analysis showed 68% correct classification with rupture for AVSV and 70% for AASA.

CONCLUSION: By comparing aneurysm geometry with the bounding sphere, we found a trend associating the ratios of aneurysm volume and surface area with rupture. These geometric parameters may be useful for understanding the influence of morphology on the risk of aneurysm rupture.

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