Awake craniotomy and brain mapping for eloquent cortex in patients with supratentorial tumors: a preliminary report

Malignant brain tumours are incurable at present. Since none of the hitherto used treatment methods allows to significantly extend these patients' survival time, the basic aim is to improve their quality of life. Intraoperative brain mapping seems to be an approach enabling to minimize the risk of irreversible damages to functionally important structures of the brain. In the Department of Neurosurgery of the Medical University of ?ód? awake craniotomy with stimulation of eloquent cortex was attempted from May 1999 to July 2000 in 13 patients aged 16 to 77 years. In two patients the attempt of intraoperative awakening was unsuccessful. In 8 out of the 11 awakened patients intraoperative brain mapping had a significant effect on the course of surgery (i.e. on the resection magnitude and "safe corridor"). Out of six patients with tumors situated in the neighbourhood of motor cortex--one developed a severe and permanent paresis of the upper limb. On the grounds of the literature and the authors' own experience an algorithm of awake craniotomy and intraoperative brain mapping was worked out.     

Assessing coronary sinus blood flow in patients with coronary artery disease: a comparison of phase-contrast MR imaging with positron emission tomography

OBJECTIVE: This study was performed to determine whether MR imaging can be used to reliably measure global myocardial blood flow and coronary flow reserve in patients with coronary artery disease as compared with such measurements obtained by positron emission tomography (PET). SUBJECTS AND METHODS: We measured myocardial blood flow first at baseline and then after dipyridamole-induced hyperemia in 20 patients with coronary artery disease. Myocardial blood flow as revealed by MR imaging was calculated by dividing coronary sinus flow by the left ventricular mass. Coronary flow reserve was calculated by dividing the rate of hyperemic flow by the rate of baseline flow. RESULTS: Using MR imaging, myocardial blood flow at baseline was 0.73 +/- 0.23 mL x min(-1) x g(-1), and at hyperemia the blood flow was 1.43 +/- 0.37 mL x min(-1) x g(-1), yielding an average coronary flow reserve of 1.99 +/- 0.47. Using PET, myocardial blood flow was 0.89 +/- 0.21 mL x min(-1) x g(-1) at baseline and 1.56 +/- 0.42 mL x min(-1) x g(-1) at hyperemia, yielding an average coronary flow reserve of 1.77 +/- 0.36. The correlation of myocardial blood flow and coronary flow reserve measurements for these two methods was an r of 0.80 (p < 0.01) and an r of 0.50 (p < 0.05), respectively. CONCLUSION: This study shows that myocardial blood flow measurements obtained using MR imaging have a good correlation with corresponding PET measurements. Coronary flow reserve measurements obtained using MR imaging had only moderate correlation with PET-obtained measurements. Our results suggest that MR imaging flow quantification could potentially be used for measuring global myocardial blood flow in patients in whom interventional treatment for coronary artery disease is being evaluated.     

Iron overload: accuracy of in-phase and out-of-phase MRI as a quick method to evaluate liver iron load in haematological malignancies and chronic liver disease

Objectives

The purpose of this prospective study was to evaluate the accuracy of in-phase and out-of-phase imaging to assess hepatic iron concentration in patients with haematological malignancies and chronic liver disease.

Methods

MRI-based hepatic iron concentration (M-HIC, μmol g^–1) was used as a reference standard. 42 patients suspected of having iron overload and 12 control subjects underwent 1.5 T in- and out-of-phase and M-HIC liver imaging. Two methods, semi-quantitative visual grading made by two independent readers and quantitative relative signal intensity (rSI) grading from the signal intensity differences of in-phase and out-of-phase images, were used. Statistical analyses were performed using the Spearman and Kruskal–Wallis tests, receiver operator curves and κ coefficients.

Results

The correlations between M-HIC and visual gradings of Reader 1 (r=0.9534, p<0.0001) and Reader 2 (r=0.9456, p<0.0001) were higher than the correlations of the rSI method (r=0.7719, p<0.0001). There was excellent agreement between the readers (weighted κ=0.9619). Both visual grading and rSI were similar in detecting liver iron overload: rSI had 84.85% sensitivity and 100% specificity; visual grading had 85% sensitivity and 100% specificity. The differences between the grades of visual grading were significant (p<0.0001) and the method was able to distinguish different degrees of iron overload at the threshold of 151 μmol g^–1 with 100% positive predictive value and negative predictive value.

Conclusion

Detection and grading of liver iron can be performed reliably with in-phase and out-of-phase imaging. Liver fat is a potential pitfall, which limits the use of rSI.Iron overload is a clinically recognised condition with variety of aetiologies and clinical manifestations [1-4]. Liver iron concentration correlates closely with the total body iron stores [5]. The excess iron accumulates mainly in the liver and the progressive accumulation of toxic iron can lead to organ failure if untreated [2,4]. Several diseases causing iron overload, such as transfusion-dependent anaemia, haematological malignancies, thalassaemia, haemochromatosis and chronic liver disease, result in a large number of patients with a potentially treatable iron overload [1,2,4].Several quantitative MRI methods for iron overload measurement by multiple sequences have been established, such as proportional signal intensity (SI) methods and proton transverse relaxation rates (R₂, R₂*) [4,6,7]. A gradient echo liver-to-muscle SI-based algorithm [8] has been widely validated and used for quantitative liver iron measurement [8-11]. MRI-based hepatic iron concentration (M-HIC, μmol g^–1 liver dry weight) with corresponding R₂* [9] can be calculated with this method which is a directly proportional linear iron indicator, virtually independent of the fat fraction, as the echo times are taken in-phase [8,9]. This method showed a high accuracy in calibrations with the biochemical analysis of liver biopsies (3–375 μmol g^–1) of 174 patients. The mean difference of 0.8 μmol g^–1 (95% confidence interval of –6.3 to 7.9) between this method and the biochemical analysis is quite similar [8] to the intra-individual variability found in histological samples [12].The quantitative MRI methods are based on progressive SI decay, with the longer echo times due to relaxing properties of iron. Interestingly, this iron-induced effect is seen in MR images with multiple echoes [4,6-11], but also in dual-echo images, namely in-phase and out-of-phase imaging [13,14]. In-phase and out-of-phase imaging has become a routine part of liver MRI, performed initially for liver fat detection [6,13,15]. Quite recently some investigators have noticed an alternative approach of the sequence to detect liver iron overload due to the more pronounced SI decrease on in-phase images with the longer echo time [13,14]. Yet, to our knowledge, this is the first prospective study evaluating the accuracy of in-phase and out-of-phase imaging to assess hepatic iron concentration.The purpose of the study was to evaluate the capability and accuracy of dual-echo in-phase and out-of-phase imaging to assess hepatic iron concentration at 1.5 T in patients with haematological malignancies and chronic liver disease. MRI-based hepatic iron concentration (M-HIC, μmol g^–1) was used as a reference standard [8,9].     

Localized proton NMR spectroscopy in the striatum of patients with idiopathic parkinson's disease: a multicenter pilot study

Single voxel proton MRS was used to study brain metabolism in the striatum of patients diagnosed with idiopathic Parkinson's disease (PD). Peak metabolite ratios in long echo time spectra were evaluated in 151 patient spectra and 97 age-matched control spectra collected at four participating institutions using identical hardware and clinical protocols. Combining data from all ages (27–83 years old) showed no significant difference between patient and control ratios. However, in an elderly subset of patients (51–70 years old), a significant decrease in striatal N-acetylaspartate (NAA)/choline (Cho) was observed. Also, a significant decrease in the mean NAA/Cho ratio was observed in patients versus controls for patients not being treated with Sinemet (Du Pont Pharm, Wilmingon, DE) (hereafter referred to as levodopa/carbidopa). This result is consistent with the hypothesis that NAA may provide a reversible spectroscopic marker for neuronal dysfunction, although a prospective follow-up study will be needed to confirm this. Quantitation of MRS would be useful to exclude the possibility that a change in Cho levels affected the NAA/Cho ratios.     

Paramagnetic contrast enhancement at 0.02 T: An experimental study using Gd-DOTA in normal and hydronephrotic kidneys

Both normal and experimentally hydronephrotic rabbits were imaged at 0.02 T using partial saturation (PS 160/30) and inversion recovery (IR 1000/200/40) sequences. The signal intensity of normal renal medulla and cortex markedly increased after the injection of 0.1 mmol/kg of Gd-DOTA. In the unilateral total hydronephrosis the dilated renal pelvis did not contrast enhance after 15 and 35 min of Gd-DOTA injection. The enhancement pattern was similar in 1- and 3-week-old hydronephrosis. The effect of Gd-DOTA on renal T1 times at 0.02 T was studied using rats. Fifteen minutes after the Gd-DOTA injection (0.1 mmol/kg) the TI times of excised rat kidneys decreased from 311 to 90 ms. The authors conclude that the enhancement of the MR signal of the kidney by Gd-DOTA at an ultralow magnetic field (0.02 T) is similar to its enhancement at higher fieldss (>0.15 T). © 1988 Academic Press, Inc.     

The effect of haemosiderosis and blood transfusions on the T2 relaxation time and 1/T2 relaxation rate of liver tissue.

Patients with chronic anaemia need repeated blood transfusions, which eventually lead to iron overload. The excess iron from blood transfusions is deposited in the reticuloendothelial system and in the parenchymal cells of the liver, spleen and other organs. Cellular damage is likely to occur when iron overload in the liver is pronounced. Liver biopsy is still necessary to evaluate the degree of haemosiderosis or haemochromatosis. To avoid this invasive procedure, methods have been sought to determine the concentration of iron in liver tissue and to estimate the effect of the treatment of haemosiderosis or haemochromatosis. In this MRI study, the T2 relaxation time and the 1/T2 relaxation rate of liver were determined in 23 patients who had undergone repeated blood transfusions for chronic anaemia. The first 60 transfusions had the greatest influence on the measured T2 relaxation time, with T2 relaxation time decreasing as haemosiderosis progresses. The 1/T2 relaxation rate increases significantly in a linear fashion when the number of blood transfusions increases up to 60. After 60 transfusions the influence of additional blood transfusions on the T2 value was minimal; the same response, although in reverse, was seen in the 1/T2 relaxation rate curve. One possible explanation for this may be that the MR system could detect the effect of only a limited amount of iron excess and any concentration over this limit gives a very short T2 relaxation time and a very weak signal from the liver, which is overwhelmed by background noise. However, in mild and moderate haemosiderosis caused by blood transfusions, T2 relaxation time and 1/T2 relaxation rate reflect iron accumulation in liver tissue.     

Perspectives of self‐direction: a systematic review of key areas contributing to service users’ engagement and choice‐making in self‐directed disability services and supports

Self‐directed disability support policies aim to encourage greater choice and control for service users in terms of the health and social care they receive. The proliferation of self‐directed disability support policies throughout the developed world has resulted in a growing amount of research exploring the outcomes for service users, and their families and carers. Our understanding of the issues faced by people with disabilities, particularly how they make health and social care decisions and the key areas that determine their engagement with service providers within a self‐directed environment is limited. A synthesis of research is timely and can provide knowledge for service users and health and social care support providers to ensure their successful participation. A systematic review guided by the PRISMA approach explored (i) the key areas determining service users’ engagement with self‐directed disability services and supports, and (ii) how service users make informed decisions about providers. In October 2014 and April 2016, three databases – MEDLINE, CINAHL and Web of Science – were searched for research and review articles. Eighteen sources met the search criteria. Findings were mapped into either: key areas determining service user engagement, or service users’ informed decision‐making. Findings concerning key areas determining engagement fell into three themes – personal responsibility for budgeting, personalised approaches, and a cultural shift in practice and delivery among service providers. Findings about decision‐making yielded two themes – supporting informed decision‐making and inhibiting informed decision‐making. Literature suggests that self‐directed models of care may provide service users with increased control over the services that they receive. Increased control for some service users and their families requires independent external decision‐making support, particularly around the domains of budgeting, planning and hiring. Future research must continue to investigate the perspectives of service users pertaining to their engagement, as their participation is central to the effectiveness of the approach.     

Fractional anisotropy and mean diffusivity parameters of the brain white matter tracts in preterm infants: reproducibility of region-of-interest measurements

Background  

Diffusion tensor parameters can be analysed by fitting regions of interest (ROIs) to selected brain structures. The clinical usefulness of these measurements is influenced by their reproducibility and validity.