Injection Of Paramagnetic Contrast Agent Research Articles

The impact of schizophrenia on frontal perfusion parameters: a DSC-MRI study

We performed a dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) analysis to study the role of the demographic/clinical information on perfusion parameters between patients with schizophrenia and normal control subjects. 39 schizophrenia patients and 27 normal controls were studied with a Siemens 1.5T magnet. PWI images were obtained following intravenous injection of paramagnetic contrast agent (gadolinium-DTPA). For each perfusion parameter, i.e. relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), mean transit time (MTT) and time-to-peak (TTP), the best predictor model was computed in left and right frontal cortex following a stepwise strategy. First of all, a linear model, including all the sociodemographic information and clinical variables as predictors was computed. At each step, the least significant predictor was excluded and a new linear model was evaluated until all predictors were excluded. Then, the best predictor model was selected based on the F statistic value and on the p value. The models for the rCBF and the rCBV both in the left and right frontal cortex were estimated independently from each other, and the best models contained the same predictors, i.e. clinical state, age, and length of illness. No significant models were obtained for the MTT and the TTP. This study showed a decrease in rCBF and rCBV frontal cortex values in subject affected by schizophrenia. Future DSC-MRI studies should further investigate the role of cerebral perfusion for the pathophysiology of the disease by recruiting first-episode patients and by considering cerebellar, parietal and temporal regions.

Principles and Technical Aspects of Perfusion Magnetic Resonance Imaging

Perfusion magnetic resonance imaging (pMRI) is a special technique for evaluation of blood flow. Exogenous pMRI methods which are dynamic susceptibility contrast (DSC) and dynamic contrast-enhanced (DCE) use an intravenous bolus injection of paramagnetic contrast agent. In contrast, an endogenous pMRM method which is arterial spin labeling (ASL) use diffusible blood in body. In order to scan pMRI in human, technical optimizations are very important according to disease conditions. For examples, DSC is popularly used in patients with acute stroke due to its short scan time, while DSC or DCE provides the various perfusion indices for patients with tumor. ASL is useful for children, women who are expected to be pregnant, and in patients with kidney diseases which are problematic in nephrogenic systemic fibrosis (NSF). Perfusion MRI does not require any injection of radioisotopes. We expect that demand for perfusion MRI will be higher in evaluating drug efficacy and other treatment effects.

Increased fronto-temporal perfusion in bipolar disorder

Objectives Previous imaging reports showed over-activation of fronto-limbic structures in bipolar patients, particularly in response to emotional stimuli. In this study, for the first time, we used perfusion weighted imaging (PWI) to analyze lobar cerebral blood volume (CBV) in bipolar disorder to further explore the vascular component to its pathophysiology. Methods Fourteen patients with DSM-IV bipolar disorder (mean age ± SD = 49.00 ± 12.30 years; 6 males, 8 females) and 29 normal controls (mean age ± SD = 45.07 ± 10.30 years; 13 males, 16 females) were studied. PWI images were obtained following intravenous injection of paramagnetic contrast agent (Gadolinium-DTPA), with a 1.5 T Siemens magnet using an echo-planar sequence. The contrast of enhancement (CE), was calculated pixel by pixel as the ratio of the maximum signal intensity drop during the passage of contrast agent (Sm) by the baseline pre-bolus signal intensity (So) (CE = Sm/So ⁎100) for frontal, temporal, parietal, and occipital lobes, bilaterally, on two axial images. Higher CE values correspond to lower CBV and viceversa. Results Bipolar patients had significantly lower CE values in left frontal and temporal lobes ( p = 0.01 and p = 0.03, respectively) and significantly inverse laterality index for frontal lobe ( p = 0.017) compared to normal controls. No significant correlations between CE measure and age or clinical variables were found ( p > 0.05). Conclusion This study found increased left frontal and temporal CBV in bipolar disorder. Fronto-temporal hyper-perfusion may sustain over-activation of these structures during emotion modulation, which have been observed in patients with bipolar illness.

Magnetic resonance imaging as a potential tool for objective visualization of venous leakage in patients with veno-occlusive erectile dysfunction

Duplex Doppler ultrasonography (DDU) and dynamic infusion pharmacocavernosometry are the conventional diagnostic methods currently used to assess veno-occlusive hemodynamic status of patients with erectile dysfunction (ED). Dynamic infusion pharmacocavernosography is the standard method for demonstrating and visualization of venous leakage. To assess the potential application and utility of magnetic resonance imaging (MRI) in demonstrating and visualizing veno-occlusive dysfunction in patients with ED. A total of 28 patients, (32-56 years of age; mean 43.4+/-7.2 years), with clinical symptoms of veno-occlusive ED participated in this study. All patients have undergone DDU and dynamic infusion pharmacocavernosometry and pharmacocavernosography to assess presence of venous leakage. Patients were then evaluated with MRI and enhancement by intracavernous injection of paramagnetic contrast agent and erection was induced by intracavernosal injection of pharmacological agents. Diagnosis of ED patients with venous leakage was confirmed in all 28 patients using DDU and dynamic infusion cavernosometry-cavernosography (DICC). Venous leakage was documented by conventional DICC in 21 of 28 patients (75%). Veno-occlusive dysfunction in all patients was also assessed by MRI to localize distal, proximal or mixed locations of draining veins from the corpora cavernosa. MRI visualized venous leakage patients, in which DICC did not confirm venous leakage. MRI may be a useful diagnostic tool for assessing veno-occlusive dysfunction in ED patients and may improve diagnosis of venous leakage visualization.

Contrast-enhanced MR imaging in patients with BI-RADS 3-5 microcalcifications

The aim of this study was to evaluate the role of magnetic resonance imaging (MRI) in patients with microcalcifications classed as Breast Imaging Reporting and Data Systems (BI-RADS) 3-5. Fifty-five patients with mammographic microcalcifications classified as BI-RADS categories 3, 4 or 5 underwent MRI and biopsy with stereotactic vacuum-assisted biopsy (VAB). Our gold standard was microhistology in all cases and histology with histological grading in patients who underwent surgery. Patients with a microhistological diagnosis of benign lesions underwent mammographic follow-up for at least 12 months. MRI was performed with a 1.5-Tesla (T) unit, and T1 coronal three-dimensional (3D) fast low-angle shot sequences were acquired before and after injection of paramagnetic contrast agent (0.1 mmol/kg). MRI findings, according to the Fisher score, were classified into BI-RADS classes. In patients with cancer who underwent surgery, we retrospectively compared the extension of the mammographic and MRI findings with histological extension. Histology revealed 26 ductal in situ cancers (DCIS) and ductal microinvasive cancers (DCmic), three atypical ductal hyperplasias (ADH) and 26 benign conditions. Histological grading of the 26 patients with cancer revealed four cases of G1, 11 cases of G2 and 11 cases of G3. If we consider mammographic BI-RADS category 3 as benign and BI-RADS 4 and 5 as malignant, mammography had 77% sensitivity, 59% specificity, 63% positive predictive value (PPV), 74% negative predictive value (NPV) and 67.2% diagnostic accuracy. If we consider MRI BI-RADS categories 1, 2 and 3 as benign and 4 and 5 as malignant, MRI had 73% sensitivity, 76% specificity, 73% PPV, 76% NPV and 74.5% diagnostic accuracy. As regards disease extension, mammography had 45% sensitivity and MRI had 84.6% sensitivity. Mammography and stereotactic biopsy still remain the only techniques for characterising microcalcifications. MRI cannot be considered a diagnostic tool for evaluating microcalcifications. It is, however, useful for identifying DCIS with more aggressive histological grades. An important application of MRI in patients with DCIS associated with suspicious microcalcifications could be to evaluate disease extension after a microhistological diagnosis of malignancy, as it allows a more accurate presurgical planning.

Assessment of cerebral blood volume in schizophrenia: A magnetic resonance imaging study

Brain atrophy has consistently been observed in schizophrenia, representing a ‘gross’ evidence of anatomical abnormalities. Reduced cerebral blood volume (CBV) may accompany brain size decrement in schizophrenia, as suggested by prior small SPECT studies. In this study, we non-invasively investigated the hemisphere CBV in a large sample of patients suffering from schizophrenia with perfusion-weighted imaging (PWI). PWI images were obtained, following intravenous injection of paramagnetic contrast agent (Gadolinium-DTPA), for 54 DSM-IV patients with schizophrenia (mean age ± SD = 39.19 ± 12.20 years; 34 males, 20 females) and 24 normal controls (mean age ± SD = 44.63 ± 10.43 years; 9 males, 15 females) with a 1.5T Siemens magnet using an echo-planar sequence (TR = 2160 ms, TE = 47 ms, slice thickness = 5 mm). The contrast of enhancement (CE), a semi-quantitative parameter inversely estimating the CBV, were calculated pixel by pixel as the ratio of the maximum signal intensity drop during the passage of contrast agent (Sm) by the baseline pre-bolus signal intensity (So) (CE = Sm/So × 100) for right and left hemisphere on two axial images. Specifically, higher CE values correspond to lower CBV and viceversa Compared to normal controls, patients with schizophrenia had significantly higher bilateral hemisphere CE values ( p = 0.02) and inverse CE laterality index ( p = 0.02). This study showed abnormally reduced and inverse hemisphere CBV in a large population of patients with schizophrenia. Hypothetically, chronic low CBV may sustain neural hypoactivation and concomitant increase of free radicals, ultimately resulting in neuronal loss and cognitive impairments. Thus, altered intracranial hemodynamics may accompany brain atrophy and cognitive deficits, being a crucial factor in the pathophysiology of schizophrenia.

Evaluation of glomerular function in individual kidneys using dynamic magnetic resonance imaging.

We used the fast field-echo technique of magnetic resonance (MR) imaging with an intravenous bolus injection of paramagnetic contrast agent to evaluate glomerular function. The time-dependent curves of changes in signal intensity observed in the renal cortex and renal medulla brought about by the paramagnetic contrast agent allowed insight into excretory kinetics. The time at which the cortical and medullary curves cross, the cortico-medullary (C-M) junction time, was delayed with a decrease in glomerular function. The mean C-M junction time in both kidneys showed a significant inverse correlation with total creatinine clearance (Ccr), indicating the glomerular filtration rate. The C-M junction time in an individual kidney also showed an inverse correlation with individual Ccr in each kidney. Results suggest that dynamic MR imaging is a useful tool in evaluating renal morphology and in evaluating semiquantitatively the glomerular function of the kidneys, singly and together, in a manner analogous to radionuclide scintigraphy.