2,366 research outputs found
Diffusion tensor magnetic resonance imaging of prostate cancer
Purpose: To explore the feasibility of 3 T magnetic resonance (MR)
diffusion tensor imaging (DTI) and fiber tracking (FT) in patients
with prostate cancer.
Materials and methods: Thirty consecutive patients (mean age,
62.5 years) with biopsy proven prostate cancer underwent 3 T-MR
imaging (MRI) and DTI using a 6-channel external phased-array
coil before radical prostatectomy. Regions of interest of 14 pixels
were defined in tumors and nonaffected areas in the peripheral zone
(PZ) and central gland (CG), according to histopatology after radical
prostatectomy. Apparent diffusion coefficient (ADC) and fractional
anisotropy (FA) values were determined. Differences in mean ADC
and FA values among prostate cancer, normal PZ and CG were
compared by 2-sided Student t test. The predominant diffusion
direction of the prostate anisotropy was color coded on a directionally
encoded color (DEC) map. A 3D reconstruction of fiber tract
orientations of the whole prostate was determined using the continuous
tracking method. The overall image quality for tumor localization
and local staging was assessed in retrospective matching
with whole-mount section histopathology images. Nodules detected
at MRI were classified as matched lesions if tumor presence and
extension were evidenced at histopathology.
Results: For all the patients, the DTI sequence images were suitable
for the evaluation of the zonal anatomy of the prostate gland and the
tumor localization. Quantitative evaluation of the regions of interest
(ROIs) showed a mean ADC value significantly lower in the peripheral
neoplastic area (1.06 0.37 10 3 mm2/s) than in the
normal peripheral portion (1.95 0.38 10 3 mm2/s) (P 0.05).
The mean FA values calculated in the normal peripheral (0.47
0.04) and central area (0.41 0.08) were very similar (P 0.05).
The mean FA values in the neoplastic lesion (0.27 0.05) were
significantly lower (P 0.05) than in the normal peripheral area and
in the normal central and adenomyomatous area. DEC showed a
top-bottom type preferential direction in the peripheral but not in the
central area, with the tumor lesions reducing the diffusion coding
direction represented as color zones tending toward gray. Tractographic
analysis permitted good delineation of the prostate anatomy
(capsule outline, peripheral and central area borders) and
neoplastic lesion extension and capsule infiltration compared
with histopathology.
Conclusions: Three tesla DTI of the prostate gland is feasible and
has the potential for providing improved diagnostic information
Simultaneous in vivo positron emission tomography and magnetic resonance imaging
Positron emission tomography (PET) and magnetic resonance imaging (MRI) are widely used in vivo imaging technologies with both clinical and biomedical research applications. The strengths of MRI include high-resolution, high-contrast morphologic imaging of soft tissues; the ability to image physiologic parameters such as diffusion and changes in oxygenation level resulting from neuronal stimulation; and the measurement of metabolites using chemical shift imaging. PET images the distribution of biologically targeted radiotracers with high sensitivity, but images generally lack anatomic context and are of lower spatial resolution. Integration of these technologies permits the acquisition of temporally correlated data showing the distribution of PET radiotracers and MRI contrast agents or MR-detectable metabolites, with registration to the underlying anatomy. An MRI-compatible PET scanner has been built for biomedical research applications that allows data from both modalities to be acquired simultaneously. Experiments demonstrate no effect of the MRI system on the spatial resolution of the PET system and <10% reduction in the fraction of radioactive decay events detected by the PET scanner inside the MRI. The signal-to-noise ratio and uniformity of the MR images, with the exception of one particular pulse sequence, were little affected by the presence of the PET scanner. In vivo simultaneous PET and MRI studies were performed in mice. Proof-of-principle in vivo MR spectroscopy and functional MRI experiments were also demonstrated with the combined scanner
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