Quantifying lumbar paraspinal intramuscular fat: Accuracy and reliability of automated thresholding models.

Background: The reported level of lumbar paraspinal intramuscular fat (IMF) in people with low back pain (LBP) varies considerably across studies using conventional T1- and T2-weighted magnetic resonance imaging (MRI) sequences. This may be due to the different thresholding models employed to quantify IMF. In this study we investigated the accuracy and reliability of established (two-component) and novel (three-component) thresholding models to measure lumbar paraspinal IMF from T2-weighted MRI. Methods: In this cross-sectional study, we included MRI scans from 30 people with LBP (50% female; mean (SD) age: 46.3 (15.0) years). Gaussian mixture modelling (GMM) and K-means clustering were used to quantify IMF bilaterally from the lumbar multifidus, erector spinae, and psoas major using two and three-component thresholding approaches (GMM2C; K-means2C; GMM3C; and K-means3C). Dixon fat-water MRI was used as the reference for IMF. Accuracy was measured using Bland-Altman analyses, and reliability was measured using ICC3,1. The mean absolute error between thresholding models was compared using repeated-measures ANOVA and post-hoc paired sample t-tests (α = 0.05). Results: We found poor reliability for K-means2C (ICC3,1 ≤ 0.38), moderate to good reliability for K-means3C (ICC3,1 ≥ 0.68), moderate reliability for GMM2C (ICC3,1 ≥ 0.63) and good reliability for GMM3C (ICC3,1 ≥ 0.77). The GMM (p < .001) and three-component models (p < .001) had smaller mean absolute errors than K-means and two-component models, respectively. None of the investigated models adequately quantified IMF for psoas major (ICC3,1 ≤ 0.01). Conclusions: The performance of automated thresholding models is strongly dependent on the choice of algorithms, number of components, and muscle assessed. Compared to Dixon MRI, the GMM performed better than K-means and three-component performed better than two-component models for quantifying lumbar multifidus and erector spinae IMF. None of the investigated models accurately quantified IMF for psoas major. Future research is needed to investigate the performance of thresholding models in a more heterogeneous clinical dataset and across different sites and vendors.

Endoscopic anatomy of persistent trigeminal artery: a cadaveric study.

BACKGROUND: Persistent trigeminal artery (PTA) is one of the carotid-basilar anastomoses and occasionally complicates vascular or neoplastic pathology. The aim of this study was to become more familiar with the anatomy associated with PTA using an endoscopic view. MATERIAL AND METHODS: PTA was incidentally encountered in a fresh cadaver. Purely endoscopic approaches via supraorbital (extradural and intradural routes), endonasal, and retrosigmoid routes were performed with 4-mm, 0- and 30-degree rigid endoscopes. RESULTS: The PTA belonged to Salas's lateral type and Saltzman's type 1. The supraorbital extradural approach allowed good visualization of the origin and the cavernous portion of the PTA through the infratrochlear triangle. Using the endonasal route, the cisternal portion of the PTA and its confluence to the basilar artery were demonstrated after opening the clival dura; however, the origin of the PTA and the cavernous portion of the PTA were not sufficiently exposed even using a direct approach to the cavernous sinus. The retrosigmoid approach revealed the anatomical relationship among the PTA, trigeminal nerve, and abducent nerve in the petroclival region. CONCLUSION: These 3 endoscopic approaches provided a superb image of the PTA and contribute to the anatomical comprehension of PTA. Additionally, these approaches make us more familiar with an endoscopic view of PTA.

The microvascular network of the pituitary gland: a model for the application of fractal geometry to the analysis of angioarchitecture and angiogenesis of brain tumors.

In geometrical terms, tumor vascularity is an exemplary anatomical system that irregularly fills a three-dimensional Euclidean space. This physical characteristic, together with the highly variable vessel shapes and surfaces, leads to considerable spatial and temporal heterogeneity in the delivery of oxygen, nutrients and drugs, and the removal of metabolites. Although these biological features have now been well established, quantitative analyses of neovascularity in two-dimensional histological sections still fail to view tumor architecture in non-Euclidean terms, and this leads to errors in visually interpreting the same tumor, and discordant results from different laboratories. A review of the literature concerning the application of microvessel density (MVD) estimates, an Euclidean-based approach used to quantify vascularity in normal and neoplastic pituitary tissues, revealed some disagreements in the results and led us to discuss the limitations of the Euclidean quantification of vascularity. Consequently, we introduced fractal geometry as a better means of quantifying the microvasculature of normal pituitary glands and pituitary adenomas, and found that the use of the surface fractal dimension is more appropriate than MVD for analysing the vascular network of both. We propose extending the application of this model to the analysis of the angiogenesis and angioarchitecture of brain tumors.

Microtechnologies in neurosurgery.

In the history of medicine, the understanding of the nervous system, both from an anatomical and a functional point of view, has always required new and more sophisticated tools. It has been widely demonstrated that engineering has helped towards this end. Incorporation of improved technical tools has expanded the available armamentarium to perform neurological surgery. Neurosurgery probably presents the most major challenges and always benefits from the introduction of sophisticated tools, from cranial trephination to the most modern robotics. This review examines the role of engineering to assist in neurosurgery.

Focal extra-axial hemorrahagic mass with subdural hemorrhage secondare to extramedullary hematopoiesis in idiopathic myelodysplastic sindrome.

Idiopathic myelodysplastic syndrome is a disease characterized by a clonal stem cell disorder in which megacaryocitic and granulocytic lineages are mainly involved; extramedullary myeloid metaplasia is due to abnormal location of myeloid tissue in other organs than bone marrow. Rarely the central nervous system is involved. When it happens, it is typical to find masses around the brain and pachymeningeal thickening, but it is very rare to find it associated with subdural haemorrhage, as in the case we describe in the present article. Considering our case and the literature we can suggest that radiological images associated with the clinical history of the patient suggestive for extramedullary hematopoiesis can be sufficient for a correct diagnosis and for a radiotherapy treatment, demanding surgery in the case of diagnostic doubts, massive hemorrahages or neurological decifits caused by the focal lesions.

Oligodendroglial gliomatosis cerebri. Case report.

Gliomatosis cerebri of oligodendroglial origin is very unusual. In the present article we illustrate a case of this pathology, outlining his severity and suggesting it seems to be more aggressive than the astroglial type. We give a short focus about the diagnosis and the therapy of this neoplastic disease.

Meningeal melanocytoma of the temporal lobe. An uncommon tumor in an unusual location. Case report.

Meningeal melanocytomas are rare pigmented tumors of the central nervous system. These tumors are benign melanotic lesions that derive from the melanocytes of the leptomeninges. They may occur anywhere in the cranial and spinal meninges; however, they are found prevalently in the posterior fossa and in the spinal cord. Their epidemiological features, natural history and response to treatment remain poorly understood, even if, in the last 2 years, some reviews have been published about it. We report a new case of intracranial supratentorial meningeal melanocytoma, in the temporal lobe, occurring in a 27-year-old man, admitted to our Institute with a long-time history of seizures. We report histological and radiological characteristics of our case, and briefly review the therapeutical options reported in literature. Preoperative neuroradiological finding is unclear; the preoperative diagnosis is usually meningioma, because of the long duration of symptomatology and the radiological appearance of the lesion as an extra-axial mass. Diagnosis of these lesions, as in our case, is made intraoperatively by the gross, jet-black appearance of the tumor and by histological examination. In spite of the benign biologic behaviour, the prognosis remains uncertain, because of the possible local recurrences. According to the results of some works of the last years, it seems appropriate to use postoperative radiotherapy for those patients with symptomatic residual, progressive or recurrent tumors not amenable to further resection.

Arnold's neuralgia caused by solitary fibrous tumor. Case report.

Solitary fibrous tumor (SFT) is a mesenchymal tumor which has been identified in a wide variety of localizations, including soft tissues, peritoneum, retroperitoneum, mediastinum, upper respiratory tract, nasopharyngeal sinuses, periosteum and extremities, orbit, major body cavities, intraspinal and intracranial localizations. The authors describe a case of SFT found in the neck of a young patient suffering from Arnold's neuralgia. After surgery, diagnosis of SFT was based on characteristic histopathological findings, especially on immunohistochemical positive staining for CD34 antigen. It has been described also the characteristic patterns making this diagnose sure, focusing the point that cure is possible with complete excision of the lesion.

Computerized occlusion rating: a superior predictor of aneurysm rebleeding for ruptured embolized aneurysms.

BACKGROUND AND PURPOSE: The initial angiographic occlusion rate is the strongest predictor of later rebleeding in previously ruptured coil-embolized cerebral aneurysms. Angiographic estimations of aneurysmal occlusion rates are, however, subjective in nature and confounded by methodologic problems. COR has been developed, and its superiority has been experimentally established to overcome subjective bias. The purpose of this study was to assess the clinical value of COR as a more objective predictor of aneurysm rebleeding when compared with SOR as described in the Raymond Classification. MATERIALS AND METHODS: We applied COR in a consecutive series of 249 patients. Two DSA projections were selected independently by 2 blinded investigators. In cases of disagreement on the selected projections, a consensus decision was obtained. SOR were determined by 2 independent observers according to the Raymond classification. COR was measured by 2 blinded investigators. Interobserver variations were determined for SOR and COR. COR results were compared with SOR results and stratified as 100%, 99.9%-90%, 89.9%-70%, and <70% occlusion. SOR and COR were evaluated as predictors for aneurysm rebleeding. RESULTS: Seven aneurysms rebled (2.8%; follow-up, 59 ± 35 months). In 20.9% of all cases, DSA selection was performed by consensus evaluations. Interobserver variations were statistically significant for SOR (P = .0030) but not for COR (P = .3517). Compared with COR, SOR overestimated the degree of aneurysmal occlusion in 81.9% of all cases. Only COR predicted rebleeding (P = .0162). CONCLUSIONS: Unacceptable interobserver variations were shown for the standard SOR estimations. COR substantially reduced the impact of subjective bias. COR may, therefore, serve as an easily applicable more objective predictor of aneurysm rerupture. The remaining bias of COR, caused by 2D image analysis, may be overcome by use of direct 3D measurements.

Lumbar arachnoiditis and thecaloscopy: brief review and proposed treatment algorithm.

The term arachnoiditis describes the inflammation of the meninges and subarachnoid spaces. Lumbar arachnoiditis is characterized by obliterated nerve root sleeves and the adherence of nerve roots to each other in the proximity of the cauda equina, and may be secondary to infectious diseases or tumors, iatrogenic (subsequent to spinal surgery) or idiopathic. It is not very clearly defined epidemiologically or clinically, and various theories regarding its pathophysiology have been proposed; furthermore, its treatment is difficult because there is a lack of evidence-based diagnostic and therapeutic gold standards. Thecaloscopy has been recently described as a novel technique for retrograde transcutaneous neuroendoscopic inspection of the subarachnoid structures of the lumbar thecal sac; it has also been suggested for the treatment of lumbar arachnoiditis. We here review the most modern techniques for the treatment of this disease such as thecaloscopy and neurostimulation.

Intramedullary astrocytoma with granular cell differentiation.

Granular cell astrocytomas are uncommon tumors of the central nervous system (CNS) of which no cases have been documented in the spinal cord. This variant of glioma should not be confused with benign granular cell tumor which, although rare, has been well characterized in the spinal cord. We describe here the clinical, pathological, and radiological features of such an astrocytoma arising within the spinal cord at the dorsal level. A 48-year-old female was seen after about 1 year of dorsal pain and gradual spastic paraparesis. Magnetic resonance imaging (MRI) studies showed a 2-cm contrast-enhanced mass in the spinal cord at T6-T7, which had the appearance of an astrocytoma. At surgery, the tumor was found to be infiltrating a posterior column with no dural attachment. It was debulked and dissected. The histological diagnosis was astrocytoma with granular cell differentiation. In addition to documenting a unique example of intramedullary granular cell astrocytoma, we review the literature to investigate differences from other tumors with granular changes described in the spinal cord.

De novo Formation of the Ventriculus Terminalis? A Brief Report of a Special Case.

The ventriculus terminalis is an ependymal cystic cavity in the conus medullaris, sometimes found in children. Persistence of the ventriculus terminalis in adults can cause lower back pain or neurological disturbances. However, there are no literature reports of de novo formation of a ventriculus terminalis in the conus medulallaris, as in the case we illustrate here.

Intradural spinal metastasis of renal clear cell carcinoma causing cauda equina syndrome.

Metastasis of renal clear cell carcinoma to the spinal cord are quite rare. Intradural localization causing a cauda equina syndrome has been previously reported only in two cases. The present report details the clinical, surgical and neuroradiological findings of a third case requiring emergency surgery, and presents data available from a brief review of cases reported in the literature. From the data available in the literature, we suggest that cerebral and spinal MRI and PET imaging should be widely performed in the staging of patients treated for renal clear cell carcinoma, in order to early detect CNS involvement.