Added Value of Spectroscopy to Perfusion MRI in the Differential Diagnostic Performance of Common Malignant Brain Tumors.

BACKGROUND AND PURPOSE: Perfusion and spectroscopic MR imaging provide noninvasive physiologic and metabolic characterization of tissues, which can help in differentiating brain tumors. We investigated the diagnostic role of perfusion and spectroscopic MR imaging using individual and combined classifiers of these modalities and assessed the added performance value that spectroscopy can provide to perfusion using optimal combined classifiers that have the highest differential diagnostic performance to discriminate lymphomas, glioblastomas, and metastases. MATERIALS AND METHODS: From January 2013 to January 2016, fifty-five consecutive patients with histopathologically proved lymphomas, glioblastomas, and metastases were included after undergoing MR imaging. The perfusion parameters (maximum relative CBV, maximum percentage of signal intensity recovery) and spectroscopic concentration ratios (lactate/Cr, Cho/NAA, Cho/Cr, and lipids/Cr) were analyzed individually and in optimal combinations. Differences among tumor groups, differential diagnostic performance, and differences in discriminatory performance of models with quantification of the added performance value of spectroscopy to perfusion were tested using 1-way ANOVA models, receiver operating characteristic analysis, and comparisons between receiver operating characteristic analysis curves using a bivariate χ2, respectively. RESULTS: The highest differential diagnostic performance was obtained with the following combined classifiers: maximum percentage of signal intensity recovery-Cho/NAA to discriminate lymphomas from glioblastomas and metastases, significantly increasing the sensitivity from 82.1% to 95.7%; relative CBV-Cho/NAA to discriminate glioblastomas from lymphomas and metastases, significantly increasing the specificity from 92.7% to 100%; and maximum percentage of signal intensity recovery-lactate/Cr and maximum percentage of signal intensity recovery-Cho/Cr to discriminate metastases from lymphomas and glioblastomas, significantly increasing the specificity from 83.3% to 97.0% and 100%, respectively. CONCLUSIONS: Spectroscopy yielded an added performance value to perfusion using optimal combined classifiers of these modalities, significantly increasing the differential diagnostic performances for these common brain tumors.

Mathematical modeling of metabolism and hemodynamics.

We provide a mathematical study of a model of energy metabolism and hemodynamics of glioma allowing a better understanding of metabolic modifications leading to anaplastic transformation from low grade glioma. This mathematical analysis allows ultimately to unveil the solution to a viability problem which seems quite pertinent for applications to medecine.

[Multimodal magnetic resonance imaging of brain tumors]. / Imagerie multimodale par résonance magnétique des tumeurs cérébrales.

Magnetic resonance imaging arose as a reference for diagnosis, pre-therapeutic and follow-up of brain tumors. Among parameters obtained from standard MRI (of low specificity), only volumetric growth allows prognostic information. The multiple "advanced" sequences have leaded to increase both sensitivity and specificity of brain MRI. Yet, perfusion-weighted imaging and spectroscopy provide metabolic information, and diffusion tensor imaging and cortical activation provide functional information. Characterization, grading, therapeutic management and follow-up have improved, with prognostic information.

Predicting the outcome of grade II glioma treated with temozolomide using proton magnetic resonance spectroscopy.

BACKGROUND: This study was designed to evaluate proton magnetic resonance spectroscopy ((1)H-MRS) for monitoring the WHO grade II glioma (low-grade glioma (LGG)) treated with temozolomide (TMZ). METHODS: This prospective study included adult patients with progressive LGG that was confirmed by magnetic resonance imaging (MRI). Temozolomide was administered at every 28 days. Response to TMZ was evaluated by monthly MRI examinations that included MRI with volumetric calculations and (1)H-MRS for assessing Cho/Cr and Cho/NAA ratios. Univariate, multivariate and receiver-operating characteristic statistical analyses were performed on the results. RESULTS: A total of 21 LGGs from 31 patients were included in the study, and followed for at least n=14 months during treatment. A total of 18 (86%) patients experienced a decrease in tumour volume with a greater decrease of metabolic ratios. Subsequently, five (28%) of these tumours resumed growth despite the continuation of TMZ administration with an earlier increase of metabolic ratios of 2 months. Three (14%) patients did not show any volume or metabolic change. The evolutions of the metabolic ratios, mean(Cho/Cr)(n) and mean(Cho/NAA)(n), were significantly correlated over time (Spearman ρ=+0.95) and followed a logarithmic regression (P>0.001). The evolutions over time of metabolic ratios, mean(Cho/Cr)(n) and mean(Cho/NAA)(n), were significantly correlated with the evolution of the mean relative decrease of tumour volume, mean(ΔV(n)/V(o)), according to a linear regression (P<0.001) in the 'response/no relapse' patient group, and with the evolution of the mean tumour volume (meanV(n)), according to an exponential regression (P<0.001) in the 'response/relapse' patient group. The mean relative decrease of metabolic ratio, mean(Δ(Cho/Cr)(n)/(Cho/Cr)(o)), at n=3 months was predictive of tumour response over the 14 months of follow-up. The mean relative change between metabolic ratios, mean((Cho/NAA)(n)-(Cho/Cr)(n))/(Cho/NAA)(n), at n=4 months was predictive of tumour relapse with a significant cutoff of 0.046, a sensitivity of 60% and a specificity of 100% (P=0.004). CONCLUSIONS: The (1)H-MRS profile changes more widely and rapidly than tumour volume during the response and relapse phases, and represents an early predictive factor of outcome over 14 months of follow-up. Thus, (1)H-MRS may be a promising, non-invasive tool for predicting and monitoring the clinical response to TMZ.

A comparative study of perfusion measurement in brain tumours at 3 Tesla MR: Arterial spin labeling versus dynamic susceptibility contrast-enhanced MRI.

PURPOSE: To prove the feasibility of arterial spin labeling (ASL) to explore brain tumors by comparing dynamic susceptibility contrast-enhanced MRI to ASL at 3T MR. MATERIALS AND METHODS: Twenty-seven patients were included presenting 9 gliomas, 10 metastases and 8 meningiomas. All were explored by a pseudo-continuous ASL and dynamic susceptibility contrast-enhanced T2* perfusion sequence. Two neuroradiologists analyzed the cerebral blood flow (CBF) maps to assess feasibility, examination quality and quantitative comparison. The Spearman nonparametric correlation test and the Bland-Altman graphic test were used to analyze our quantitative results. RESULTS: 92% of ASL CBF maps were informative. ASL detected all lesions as well as dynamic susceptibility contrast-enhanced MRI. Both sequences provide relative quantitative CBF values closely correlated. CONCLUSION: On a 3T MR unit, ASL is a good alternative to dynamic susceptibility contrast-enhanced MRI when contrast medium is contraindicated or intravenous injection is not possible. Its results on relative CBF parameters are similar to contrast-injected perfusion.

3T MR imaging of postoperative recurrent middle ear cholesteatomas: value of periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted MR imaging.

BACKGROUND AND PURPOSE: MR diagnostic of postoperative recurrent cholesteatomas is difficult. Our purpose was to compare multishot fast spin-echo periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted MR imaging (DWI) with array spatial sensitivity encoding technique (ASSET) single-shot echo-planar DWI and late postgadolinium T1-weighted MR imaging for the detection of postoperative recurrent middle ear cholesteatomas with a 3T imaging unit. MATERIALS AND METHODS: Thirty-five patients with suggested postoperative recurrent middle ear cholesteatoma underwent 3T MR imaging with PROPELLER DWI, ASSET echo-planar DWI, and late postgadolinium T1-weighted MR imaging. Three radiologists (2 seniors, 1 fellow) analyzed unlabeled images for visualization of recurrence. Interobserver and intraobserver agreement was assessed by using the Cohen kappa statistic test. Sensitivity, specificity, and predictive value were assessed for the 3 observers. RESULTS: Nineteen recurrent cholesteatomas were diagnosed. PROPELLER interobserver agreement was very good (1, 0.89, 0.89) among the 3 observers. Intraobserver agreement between PROPELLER and T1-weighted imaging was very good to moderate (0.88, 0.57, 0.58). PROPELLER DWI provided less interobserver variability than other sequences, and the best sensitivity, specificity, and predictive value. CONCLUSIONS: On a 3T imaging unit, multishot fast spin-echo PROPELLER DWI allows an easier detection of postoperative recurrent middle ear cholesteatoma than T1-weighted imaging by reducing artifacts and by its better contrast. DWI with PROPELLER is diagnostically robust and accurate.

Dynamic contrast-enhanced T2*-weighted MR imaging: a peritumoral brain oedema study.

BACKGROUND AND PURPOSE: Glioma and meningioma are the two most common types of primary brain tumor. The aim of the present study was to analyze, using dynamic susceptibility contrast MR perfusion imaging, the effect of angiogenesis on peritumoral tissue. METHODS: In this prospective study, conducted from December 2003 to March 2005, out of 18 patients recruited, 12 were included (six with meningioma, six with glioblastoma). Using rates of maximum signal drop (MSD), we drew regions of interest (ROI) starting near the lesion, and gradually moving outwards to areas of distant edema in axial and sagittal planes at 10, 20 and 30 mm from the tumor. We also drew ROI on the contralateral brain white matter to obtain a normal baseline for comparison (relative MSD; rMSD). RESULTS: In regions of peritumoral T2 hypersignals, we observed a decrease in rMSD with distance from glioblastoma due to reduced angiogenesis, and an increase in rMSD with distance from meningioma, probably due to a reduced mass effect. CONCLUSION: In our study, dynamic susceptibility contrast MR perfusion imaging, using MSD as a parameter, revealed differences between meningioma and glioblastoma peritumoral tissue due to changes in angiogenesis.

Spine metastasis imaging: review of the literature.

Any malignant neoplasm possesses the capacity to metastasize to the musculoskeletal system. Because the spine is the most frequent site of bone metastasis, imaging must be discussed in cases of cancer. Bone marrow is the main interest in imaging the metastatic process by magnetic resonance, while X-rays allow the study of cortical involvement. This article presents our experience, and a review of the literature, in an overview of the different imaging techniques-X-rays and magnetic resonance-with emphasis on the many difficulties that can be encountered in the diagnosis and monitoring of spinal metastases, allowing a management strategy for diagnosis and follow-up.

Osteoblastic and mixed spinal metastases: evaluation of the analgesic efficacy of percutaneous vertebroplasty.

PURPOSE: To determine the analgesic efficacy of percutaneous vertebroplasty in treating osteoblastic and mixed spinal metastases. MATERIALS AND METHODS: Fifty-two patients underwent 59 vertebroplasty procedures for 103 painful vertebral metastases, among which 53 were pure osteoblastic and 50 were mixed (blastic and lytic). Analgesic efficacy was classified as "excellent," "good," "fair," and "poor." The patients were followed up at 1 month, 6 months, 12 months, 2 years, and 5 years. The mean follow-up period was 17 months. RESULTS: The analgesic efficacy rate was 86% at 1 month and 92% at 6 months (among which 71% of patients had "excellent" results and 21% had with "good" results). In most cases, it was stable. It was correlated with vertebral filling quality (Fisher test, P = .0932 at 1 month follow-up) but neither with filling volume (Mann-Whitney test, P = .143 at 1 month) nor with the vertebral structure, pure blastic or mixed (Fisher test, P = .784 at 1 month). There were 5 filling failures (4.7%) whose occurrence was correlated with the pure blastic structure of the vertebra (Mann-Whitney test, P = .033). Local clinical complications were observed in 5 cases (8.5%): 1 transitory radiculalgia (1.7%), 2 durable radiculalgias (3.4%), 1 cauda equina syndrome (1.7%), and 1 hemothorax (1.7%). General clinical complications were 2 pulmonary embolisms (3.4%). No patients died. The occurrence of clinical complications was not correlated with the vertebral structure (Fisher test, P = .279). CONCLUSION: Vertebroplasty for osteoblastic and mixed metastases allows, with a well-trained operator, a satisfactory anesthesia with acceptable clinical complication rates.

Selective endovascular treatment of intracranial aneurysms using micrus microcoils: preliminary results in a series of 78 patients.

PURPOSE: To determine the safety and reliability of a new platinum microcoil (Micrus), in the treatment of intracranial aneurysms. PATIENTS AND METHODS: Seventy-eight patients (28 male and 50 female patients; age range, 28-83 years; mean age, 44 years) with 80 intracranial aneurysms were treated in 10 centers in Belgium and France. All aneurysms were smaller than 15 mm. Nine aneurysms (11%) were located in the posterior circulation and 71 (89%) in the anterior. Fifty aneurysms (63%) were ruptured and 30 (37%) unruptured. Micrus microcoil is a new platinum coil. It is electrically detached with a time of detachment close to 5 seconds. RESULTS: The degree of occlusion of the aneurysm was classified as total in 49 aneurysms (61%), subtotal in 28 cases (35%) and incomplete in 3 cases (4%). Technical complications were encountered in 10 patients (13%) including parent artery occlusion and thromboembolism (4 cases), coil migration (2 cases) and non-detachment of the coil (2 cases). The immediate morbidity rate was 1.3% and mortality rate 1.3%. CONCLUSION: Micrus microcoils are effective and safe in the selective treatment of ruptured and unruptured intracranial aneurysms. Spherical microcoils are helpful to create a good basket in the aneurysmal sac at the beginning of treatment.

Unusual origin of the artery of Adamkiewicz from the fourth lumbar artery.

The main arterial supply of the dorso-lumbar spinal cord is usually derived from a single anterior radiculo-medullary artery called the artery of Adamkiewicz and referred to as having a middle or low location. In some cases, the artery origin is higher, and a vessel which arises in the lower part of the region supplements the supply of the anterior spinal artery. In the literature, those arteries have been described as arising from L3 upwards, and have never been previously described angiographically, to our knowledge, below this level, although Suh and Alexander and Gililan have mentioned this eventuality. Of the 4,000 spinal cord angiographies performed in our institution, we report three cases in which the fourth lumbar artery flows into the anterior spinal artery of the conus medullaris. This anatomical variant may explain the sometimes devastating post-operative neurological complications from a spinal cord infarction on surgery of the lumbar spine or the abdominal aorta below L3.

Percutaneous coaxial transpedicular biopsy of vertebral body lesions during vertebroplasty.

We evaluated the safety and histological results of percutaneous transpedicular biopsy in patients undergoing vertebroplasty for vertebral collapse. Over a 6 year period, we carried out biopsies in 46 patients who underwent percutaneous injection of acrylic surgical cement for 57 collapsed vertebrae, because the diagnosis was not clearly established on clinical or imaging grounds. All procedures were performed under fluoroscopic guidance via a coaxial bitranspedicular approach used for vertebroplasty. We performed a clinical examination and CT after every procedure and approximately 6 months thereafter. Biopsies contributed to in 55 (96.5%) of the 57 vertebral lesions. Biopsy material was inadequate in one case (1.7%) and one biopsy was a false-negative (1.7%). The accuracy of the histological results was 98.2%, allowing a correct diagnosis in 55 of the 56 procedures. Of the 37 lesions in 28 patients with a history of a tumour, the final diagnosis was osteoporotic collapse in 25 (67.6%), metastasis in nine (24.3%), and myeloma in three (8.1%). The final diagnosis in the 19 lesions in 17 patients without a known tumour was osteoporotic collapse in 12 (63.2%), metastasis in five (26.3%), and amyloidosis in two (10.5%), the latter in one patient. No complications were observed.