Non-gaussian analysis of diffusion-weighted MR imaging in head and neck squamous cell carcinoma: A feasibility study.

BACKGROUND AND PURPOSE: Water in biological structures often displays non-Gaussian diffusion behavior. The objective of this study was to test the feasibility of non-Gaussian fitting by using the kurtosis model of the signal intensity decay curves obtained from DWI by using an extended range of b-values in studies of phantoms and HNSCC. MATERIALS AND METHODS: Seventeen patients with HNSCC underwent DWI by using 6 b-factors (0, 50-1500 s/mm(2)) at 1.5T. Monoexponential (yielding ADC(mono)) and non-Gaussian kurtosis (yielding apparent diffusion coefficient D(app) and apparent kurtosis coefficient K(app)) fits were performed on a voxel-by-voxel basis in selected regions of interest (primary tumors, metastatic lymph nodes, and spinal cord). DWI studies were also performed on phantoms containing either water or homogenized asparagus. To determine whether the kurtosis model provided a significantly better fit than did the monoexponential model, an F test was performed. Spearman correlation coefficients were calculated to assess correlations between K(app) and D(app). RESULTS: The kurtosis model fit the experimental data points significantly better than did the monoexponential model (P < .05). D(app) was approximately twice the value of ADC(mono) (eg, in neck nodal metastases D(app) was 1.54 and ADC(mono) was 0.84). K(app) showed a weak Spearman correlation with D(app) in a homogenized asparagus phantom and for 44% of tumor lesions. CONCLUSIONS: The use of kurtosis modeling to fit DWI data acquired by using an extended b-value range in HNSCC is feasible and yields a significantly better fit of the data than does monoexponential modeling. It also provides an additional parameter, K(app), potentially with added value.

Prostate cancer imaging.

As prostate cancer is a biologically heterogeneous disease for which a variety of treatment options are available, the major objective of prostate cancer imaging is to achieve more precise disease characterization. Magnetic resonance imaging (MRI) may enhance the staging of prostate cancer compared with clinical evaluation, transrectal ultrasound, or computed tomography (CT), and allows concurrent evaluation of prostatic, periprostatic, and pelvic anatomy. In clinical practice, the fusion of MRI or dynamic contrast-enhanced MRI (DCE-MRI) with MR spectroscopic imaging (MRSI) is improving the evaluation of cancer location, size, and extent, while providing an indication of tumor aggressiveness. Pretreatment knowledge of these prognostic variables is essential for achieving minimally invasive, patient-specific therapy.

Prospective evaluation of in vivo proton MR spectroscopy in differentiation of similar appearing intracranial cystic lesions.

Proton MR spectroscopy (PMRS) has been found to be useful in differentiating various cystic intracranial lesions. The purpose of the present study was to prospectively evaluate the spectral pattern of various cystic lesions of brain with similar imaging appearances and to determine the accuracy of this technique in the differential diagnosis of these lesions. Fifty-one patients with intracranial cystic lesions (21 abscesses, 20 gliomas, 3 hydatid cysts, 3 arachnoid cysts, 1 case each of glioependymal cyst, xanthogranuloma, infarction and acoustic neuroma) were evaluated with conventional MR imaging and in vivo PMRS. Ex vivo PMRS of the cystic contents aspirated at surgery in 31 cases was also done to confirm the in-vivo results. Preoperative diagnosis of the lesions was based on the results of in vivo PMRS. In vivo PMRS accurately predicted the pathology in 92% of the cases. We conclude that in-vivo PMRS complements imaging in better characterization of cystic intracranial mass lesions.

Effects of 2-deoxy-D-glucose on Acanthocheilonema viteae: rodent filariids as studied by multinuclear NMR spectroscopyt.

A well known glucose antimetabolite, 2-deoxy glucose (2DG) widely used in chemotherapy of cancer along with radiation, was evaluated as an antifilarial agent by nuclear magnetic resonance. The uptake and metabolism of 2DG in the experimental filarial infection Acanthocheilonema viteae was studied by in vivo multinuclear NMR. An unusually long retention time of 2DG6P within these parasites was observed on continuous 31P NMR monitoring, along with a decrease in ATP levels. These results led to therapeutic investigation in A. viteae infected host Mastomys coucha. 2DG showed a remarkable adulticidal activity (73.6%) with 50% sterilization of surviving female worms at a dose of 250 mg/kg x 5, p.o. NMR observations and activity profile substantiate the findings of one another, directed towards the hitting of bioenergetic machinery of A. viteae by macrofilaricidal agent (2DG).

Metabolite mapping of human filarial parasite, Brugia malayi with nuclear magnetic resonance.

Metabolite mapping of human filarial parasite, Brugia malayi was carried out in vitro as well as in situ in host Mastomys coucha by 31P nuclear magnetic resonance (NMR) spectroscopy. Detection of parasites by visualizing contrast spots due to pathologic changes was observed by 1H magnetic resonance imaging (MRI). Major metabolites of adult B. malayi observed by 31P-NMR spectroscopy were of sugar phosphates (SP), phosphomonoesters (PME), glycerophosphoryl-ethanolamine (GPE), -choline (GPC), phosphoenolpyruvate (PEP), inorganic phosphate (Pi), nucleoside diphosphosugar and nucleotides-mono, -di and -tri phosphates. PEP and GPC were present in high concentration; PEP being the major energy reservoir and GPC the major phospholipid in this species of filaria. The 31P NMR spectra of testis of mastomys, showed seven major peaks of SP, PME, phosphocreatine (PCr), phosphodiesters (PDE), Pi, and nucleotides di- and tri-phosphates. The 31P-NMR spectra of testis of B. malayi infected animal also consisted of seven major peaks with significant decrease in the SP and PME peak showing changes in the carbohydrate and lipid metabolism of filaria infected testis. Thus, in vivo 31P MRS provided a non-invasive assessment of tissue bioenergetics and phospholipid metabolism.

1H magnetic resonance imaging and 31P magnetic resonance spectroscopy in experimental filariasis.

1H Magnetic resonance imaging and 31P magnetic resonance spectroscopy (MRS) have been carried out in experimental rodent filariasis, i.e., Acanthocheilonema viteae infection in the rodent host, Mastomys coucha. The T2-weighted image of the infected host shows fine hyperintense thread like structures of adult filariid nests in the cervical region. 31P MRS of normal and infected hosts, localized over the same region of interest, show seven major peaks corresponding to phosphomonoesters (including glucose-6-phosphate, fructose-6-phosphate, fructose-1-6-diphosphate, phosphorylcholine, and adenine monophosphate or AMP), inorganic phosphate, glycerophosphorylcholine, phosphoenolpyruvate, phosphocreatine and nucleoside di- and tri-phosphates. Concentrations of phosphomonoesters (PMEs) are higher in the normal rodent compared with the infected ones. In vivo 31P MRS provides a non-invasive assessment of tissue bioenergetics and phospholipid metabolism.