Value of multiparametric MRI in the work-up of prostate cancer.

The role of magnetic resonance imaging (MRI) in prostate cancer evaluation is controversial and likely underestimated. Technological advances over the past 5 years have demonstrated that multiparametric MRI, including diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI, can evaluate the actual tumor burden of a newly diagnosed prostate cancer more accurately than sextant biopsy protocols. Tumor risk, defined by the D'Amico criteria, hence can be re-evaluated by multiparametric MRI. As a result, there is increasing evidence that MRI before repeat or even initial biopsy can accurately select patients who require immediate biopsies and those in whom biopsy could be deferred. Also, a relationship between apparent diffusion coefficient (ADC), calculated from DWI, and Gleason score was found. Thus, MRI before biopsy helps to detect high-grade tumors to target biopsies within areas of low ADC values. To achieve good targeting accuracy, transrectal ultrasound (TRUS)-MRI image registration is necessary. Three-dimensional deformable registration is sufficiently accurate to match TRUS and MRI volumes with a topographic precision of 1 mm. Real-time MRI-guided biopsy is another technique under evaluation. Both approaches will allow for increasing acceptance of focal therapies, should these techniques be validated in the future.

Conduction block--the diagnostic value in the early stage of Guillain-Barre syndrome.

Immune-mediated segmental demyelination is the basic pathomorphological substrate of the Guillain-Barre syndrome (GBS). The aim of the study is to determine the diagnostic value of the conduction block in the early stage of GBS, as well as its changes during of the development of the disease. Sixteen patients with GBS were examined. Electroneurography (motor nerve conduction studies) was performed at interval from the third day of the onset till the first year. Partial CB in the early stage of the disease (range 0-15 days) was registered in 81,2% of the patients. In demyelinating forms of GBS partial CB was determined in 61% of the investigated nerves. It is the most often observed in peroneal nerves, followed by tibial, ulnar and median nerves in the same order. The maximal reduction of the amplitude of the CMAP (maximal CB) was registered before the 30th day from the onset of the disease with following recovery on the sixth month and first year. Partial CB is more often observed in the early phase of GBS, when it could be the only sign of demyelination. When patients reached a clinical plateau, progressive slowing of motor nerve conduction and increasing CB were registered. Proximal CB was revealed more often than distal CB, because of the typical initial localization of the process. In the early phase of GBS, proximal CB is most often found in lower limbs (in peroneal nerve, followed by tibial nerve). In patients with axonal damage, CB was more severe than in demyelinating group. Partial CB is an important diagnostic criterion for segmental demyelination, which helps for confirming the diagnosis of early GBS, when conduction velocity and other electrodiagnostic criteria for demyelination are normal.

DCE-MRI: a review and applications in veterinary oncology.

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a functional imaging technique that assesses the physiology of tumour tissue by exploiting abnormal tumour microvasculature. Advances made through DCE-MRI include improvement in the diagnosis of cancer, optimization of treatment choices, assessment of treatment efficacy and non-invasive identification of prognostic information. DCE-MRI enables quantitative assessment of tissue vessel density, integrity, and permeability, and this information can be applied to study of angiogenesis, hypoxia and the evaluation of various biomarkers. Reproducibility of DCE-MRI results is important in determining the significance of observed changes in the parameters. As improvements are made towards the utility of DCE-MRI and interpreting biologic associations, the technique will be applied more frequently in the study of cancer in animals. Given the importance of tumour perfusion with respect to tumour oxygenation and drug delivery, the use of DCE-MRI is a convenient and powerful way to gain basic information about a tumour.

Multiparametric MRI features of granulomatous prostatitis and tubercular prostate abscess.

The authors report the diffusion and contrast-enhanced MRI appearance of five cases of granulomatous prostatitis (GP), non-specific (two cases) and infectious post-Bacillus Calmette-Guerin (BCG) therapy (three cases, with a tubercular abscess in two of them). All patients had raising PSA levels and abnormal DRE. History of BCG therapy or acute prostatitis was present in four patients. Multiparametric MRI (T2W-MRI, DW-MRI and DCE-MRI) was performed before biopsies. Diagnosis was confirmed by TRUS-guided biopsies in four cases and by transurethral resection in one case. MRI showed a tumor-like appearance in three cases, an abscess-like appearance in one case and a combined tumor/abscess-like appearance in one case. Extraprostatic fat was infiltrated in three patients, simulating T3a disease. Histologically, caseous necrosis was found when MRI showed abcedation. Demonstration of occult tubercular abscesses in post-BCG GP may have therapeutic implications and MRI is useful prior to surgical or interventional drainage of large caseous abscesses.

SU-D-BRB-06: Comprehensive Population-Averaged Arterial Input Function (AIF) for DCE-MRI of Head and Neck Cancer.

PURPOSE: To generate a composite population-averaged(PA)-AIF for quantitative analysis of DCE-MRI data in head and neck (H&N) patients that is based on the right (RT) and left (LT) carotids, two pre-treatment scans, and one post-treatment scan. METHODS: Twenty patients were imaged while undergoing concurrent chemoradiation (CRT) for H&N malignancies. The imaging protocol (1) included two baseline scans one week apart (Base1, Base2), and one scan 1 week post-CRT (Post). For each patient and time point, regions of interest (ROIs) in both the RT and LT carotids were drawn on coronal images. The plasma concentration curves of all ROIs were averaged and fit to a bi-exponential decay function to obtain the final PA- AIF (AvgAll). The ROIs were also divided by time point to obtain AvgBasel, AvgBase2, and AvgPost AIFs. The vascular transfer constant for both primary and nodes, Ktrans , was calculated (iCAD, Inc.) using the 4 AIFs, as well as the generic Weinmann's AIF. The median Ktrans values resulting from the AvgAll AIF were compared using Bland-Altman plots with the ones obtained from each individual time point. The Wilcoxon signed-rank test was used to compare the proposed AvgAll AIF and the generic AIF. RESULTS: The plasma parameters for the AvgAll AIF were a1,2=27.1135/17.6486 kg/liter, m 1,2=11.7525/0.2054 min-1 . The differences in Ktrans values using these coefficients vs. Weinmann's were statistically significant (p<0.0001). The median Ktrans values from the AvgBasel,AvgBase2, and AvgPost AIFs were, in most cases, not significantly different from the AvgAll values, indicating that the latter is appropriate foruse at all time points. CONCLUSIONS: A population-averaged AIF for H&N was generated that accounts for differences in RT vs. LT carotids, day-today AIF fluctuations, and treatment-induced AIF changes. It is not necessary to measure a post-treatment AIF to evaluate treatment-induced Ktrans changes.l. Craciunescu et al., MedPhys, 37, 6, 2683, 2010.

Multiparametric MRI is helpful to predict tumor focality, stage, and size in patients diagnosed with unilateral low-risk prostate cancer.

To study the staging accuracy of multiparametric magnetic resonance imaging (MRI) in patients showing unilateral low-risk cancer on prostate biopsy. A total of 58 consecutive patients with low-risk cancer (D'Amico classification) and unilateral cancer involvement on prostate biopsies were included prospectively. All patients underwent multiparametric endorectal MRI before radical prostatectomy, including T2-weighted (T2W), diffusion-weighted (DW) and dynamic contrast enhanced (DCE) sequences. Each gland was divided in eight octants. Tumor foci >0.2 cm(3) identified on pathological analysis were matched with MRI findings. Pathological examination showed tumor foci >0.2 cm(3) in 50/58 glands (86%), and bilateral tumor (pathological stagepT2c) in 20/58 (34%). For tumor detection in the peripheral zone (PZ), T2W+DWI+DCE performed significantly better than T2W+DWI and T2W alone (P<0.001). In the transition zone (TZ), only T2W+DWI performed better than T2W alone (P=0.02). With optimal MR combinations, tumor size was correctly estimated in 77% of tumor foci involving more than one octant. Bilateral tumors were detected in 80% (16/20) of cases. In patients with unilateral low-risk prostate cancer on biopsy, multiparametric MRI can help to predict bilateral involvement. Multiparametric MRI may therefore have a prognostic value and help to determine optimal treatment in such patients.