Anatomical and functional evaluation of the myocardium in patients with acute coronary syndrome (NSTEMI) using MR imaging.

PURPOSE: The aim of our study was to evaluate the role of magnetic resonance (MR) imaging in identifying the location and extent of acute ischaemic injury to predict reversibility and distinguish areas of acute from chronic ischaemia in patients with acute coronary syndrome non- ST-elevation myocardial infarction (NSTEMI). MATERIALS AND METHODS: We evaluated 22 patients with NSTEMI acute coronary syndrome confirmed by coronary angiography (CA). We studied ventricular function indices and segmental changes in wall thickness and kinetics by cine-MR imaging sequences. Subsequently, we evaluated myocardial wall oedema with T2-weighted black-blood short-tau inversion recovery turbo spin echo (T2 BB-STIRTSE) sequences and identified areas of myocardial necrosis using T1-weighted turbo field-echo inversion recovery (T1 TFE-IR) sequences after contrast material administration. RESULTS: The results obtained with the single sequences were as follows: T2 BB-STIR-TSE: 96.8% sensitivity, 100% specificity, 99.7% negative predictive value, 99.7% positive predictive value; T1 TFE-IR: 45.8% sensitivity, 96.9% specificity, 92.3% negative predictive value, 90.3% positive predictive value; systolic wall thickening: 87.5% sensitivity, 91.8% specificity, 98.7% negative predictive value, 50% positive predictive value, 91.4% accuracy. CONCLUSIONS: Our study suggests that the sequences used for evaluating oedema and assessing viability allow for precise localisation and differentiation of areas of acute and chronic ischaemia by quantifying the possible mismatch between ischaemia and necrosis.

Malignant renal neoplasms: correlation between ADC values and cellularity in diffusion weighted magnetic resonance imaging at 3 T.

PURPOSE: This study aimed at exploring the feasibility of high-field diffusion-weighted magnetic resonance imaging (DW-MRI) (3 T) and to correlate apparent diffusion coefficient (ADC) values with tumour cellularity in renal malignancies. MATERIALS AND METHODS: Thirty-seven patients (ten healthy volunteers and 27 patients with suspected renal malignancy) underwent T1-, T2-weighted and T1-weighted contrast-enhanced magnetic resonance imaging (MRI). Diffusion-weighted images were obtained with a single-shot spin-echo echo-planar imaging (SE-EPI) sequence with a b value of 500 s/mm(2). All lesions were surgically resected, and mean tumour cellularity was calculated. Comparison between tumour cellularity and mean ADC value was performed using simple linear regression analysis. RESULTS: The mean ADC value in normal renal parenchyma was 2.35+/-0.31 x 10(-3) mm(2)/s, whereas mean ADC value in renal malignancies was 1.72+/-0.21 x 10(-3) mm(2)/s. In our population, there were no statistically significant differences between ADC values of different histological types. The analysis of mean ADC values showed an inverse linear correlation with cellularity in renal malignancies (r=-0.73, p<0.01). CONCLUSIONS: DW-MRI is able to differentiate between normal and neoplastic renal parenchyma on the basis of tissue cellularity.

In vivo measurement of the apparent diffusion coefficient in normal and malignant prostatic tissue using thin-slice echo-planar imaging.

PURPOSE: Diffusion is a physical process based on the random movement of water molecules, known as Brownian movement. Diffusion-weighted imaging (DWI) is a magnetic resonance imaging (MRI) technique that provides information on such biophysical properties of tissues as density, cell organisation and microstructure, which influence the diffusion of water molecules. The aim of this study was to evaluate the ability of MRI to obtain information on the diffusion of water molecules in normal and malignant prostate tissues. MATERIALS AND METHODS: Ten volunteers and 19 patients with prostate lesions diagnosed by transrectal ultrasound (TRUS) were enrolled in our study. Morphological imaging was obtained with T2-weighted turbo spin-echo (TSE) sequences with and without fat suppression [spectral presaturation with inversion recovery (SPIR)] and an axial dynamic T1-weighted SPIR fast-field echo (FFE) sequence during intravenous administration of contrast material. DWI was obtained with a high-spatial-resolution single-shot spin-echo echo planar imaging (EPI) inversion recovery (IR) sequence. The apparent diffusion coefficient (ADC) maps were analysed by positioning an 8-pixel region of interest (ROI) over different zones of the prostate, and the focal lesion when present. The tumour was confirmed by a TRUS-guided needle biopsy taken within 1 month of the MRI examination. RESULTS: The mean ADC value of the central zones (1,512.07+/-124.85x10(-3) mm2/s) was significantly lower than the mean ADC of the peripheral zones (1,984.11+/-226.23x10(-3) mm2/s) (p<0.01). The mean ADC value of tumours (958.97+/-168.98x10(-3) mm2/s) was significantly lower than the mean values of normal peripheral zones (p<0.01). CONCLUSIONS: Our preliminary results indicate that DWI is useful for characterising tissue in the different regions of the prostate gland and in distinguishing normal from cancerous tissues, given its ability to detect early changes in the structural organisation of prostate tissue.

Magnetic resonance imaging of the prostate with spectroscopic imaging using a surface coil. Initial clinical experience.

PURPOSE: The purpose of this study was to evaluate the diagnostic ability of proton magnetic resonance spectroscopic imaging (MRSI) in the detection and localisation of prostate cancer, prospectively compared with histopathologic findings. MATERIALS AND METHODS: Magnetic resonance imaging (MRI) and MRSI were performed on 39 patients with prostate-specific antigen (PSA) levels greater than 4 ng/ml and suspicious findings at trans-rectal ultrasound (TRUS). All patients underwent a TRUS ten-core biopsy within 30 days according to a subdivision of the prostate into octants. All studies were interpreted by a dedicated radiologist who reported the areas of interest as normal, equivocal or suspicious on MRI. At MRSI, cancer was defined as possible if the ratio of choline plus creatine to citrate exceeded mean normal peripheral zone values by two standard deviations (SD) or as definite if that ratio exceeded the normal value by three SD. MRI and MRSI findings were spatially correlated with findings obtained from individual biopsy sites. RESULTS: MRI and MRSI alone had sensitivity, specificity, positive and negative predictive values and diagnostic accuracy in the detection of prostate cancer equal to 85%, 75%; 53%, 89%; 65%, 88%; 77%, 74%; and 69%, 79%, respectively. These values were 70%, 89%, 88%, 74% and 79% when MRI and MRSI were combined. Site-by-site analysis of MRI and MRSI findings and biopsy results yielded no significant correlation. CONCLUSIONS: The combination of MRSI and MRI provides a significantly higher specificity in the detection of tumours as compared with MRI alone and can be recommended as a problem-solving modality before biopsy in patients with high PSA levels and suspicious TRUS.

MR spectroscopy of prostate cancer. Initial clinical experience.

Aim of the study was to evaluate the effectiveness of proton MR Spectroscopic (MRS) imaging in the detection and localization of prostate cancer, prospectively compared with histopathologic findings. Magnetic Resonance (MR) and MRS imaging were performed in 65 patients with high levels of prostate-specific antigen (PSA) and suspicious areas at the transrectal ultrasound (TRUS). At MR areas of interest were reported as normal, equivocal or suspicious. At MRS imaging, cancer was diagnosed as "possible" if the ratio of choline plus creatine to citrate exceeded 2 SDs above mean normal peripheral zone values or as "definite" if the ratio exceeded 3 SDs. All patients underwent a TRUS 10-core biopsy within 30 days of the imaging study. MR alone showed sensitivity, specificity, positive predictive values, negative predictive values and accuracy for detection of prostate cancer of 85%, 76%, 53%, 91% and 65%, respectively, whereas MRS alone showed 89%, 77%, 78%, 69% and 83%, respectively. These values were 71%, 90%, 89%, 74% and 80% when the prostate was evaluated combining MR and MRS. The addition of MRS to the MR imaging provides a higher specificity in tumour detection and can be recommended as a problem-solving modality for patients with elevated PSA levels and suspicious TRUS before biopsy.