Comparison between dynamic gadoxetate-enhanced MRI and 99mTc-mebrofenin hepatobiliary scintigraphy with SPECT for quantitative assessment of liver function.

OBJECTIVES: To compare Gd-EOB-DTPA dynamic hepatocyte-specific contrast-enhanced MRI (DHCE-MRI) with 99mTc-mebrofenin hepatobiliary scintigraphy (HBS) as quantitative liver function tests for the preoperative assessment of patients undergoing liver resection. METHODS: Patients undergoing liver surgery and preoperative assessment of future remnant liver (FRL) function using 99mTc-mebrofenin HBS were included. Patients underwent DHCE-MRI. Total liver uptake function was calculated for both modalities: mebrofenin uptake rate (MUR) and Ki respectively. The FRL was delineated with both SPECT-CT and MRI to calculate the functional share. Blood samples were taken to assess biochemical liver parameters. RESULTS: A total of 20 patients were included. The HBS-derived MUR and the DHCE-MRI-derived mean Ki correlated strongly for both total and FRL function (Pearson r = 0.70, p = 0.001 and r = 0.89, p < 0.001 respectively). There was a strong agreement between the functional share determined with both modalities (ICC = 0.944, 95% CI 0.863-0.978, n = 20). There was a significant negative correlation between liver aminotransferases and bilirubin for both MUR and Ki. CONCLUSIONS: Assessment of liver function with DHCE-MRI is comparable with that of 99mTc-mebrofenin HBS and has the potential to be combined with diagnostic MRI imaging. This can therefore provide a one-stop-shop modality for the preoperative assessment of patients undergoing liver surgery. KEY POINTS: • Quantitative assessment of liver function using hepatobiliary scintigraphy is performed in the preoperative assessment of patients undergoing liver surgery in order to prevent posthepatectomy liver failure. • Gd-EOB-DTPA dynamic hepatocyte-specific contrast-enhanced MRI (DHCE-MRI) is an emerging method to quantify liver function and can serve as a potential alternative to hepatobiliary scintigraphy. • Assessment of liver function with dynamic gadoxetate-enhanced MRI is comparable with that of hepatobiliary scintigraphy and has the potential to be combined with diagnostic MRI imaging.

Closed-form solution of the convolution integral in the magnetic resonance dispersion model for quantitative assessment of angiogenesis.

Prostate cancer (PCa) diagnosis and treatment is still limited due to the lack of reliable imaging methods for cancer localization. Based on the fundamental role played by angiogenesis in cancer growth and development, several dynamic contrast enhanced (DCE) imaging methods have been developed to probe tumor angiogenic vasculature. In DCE magnetic resonance imaging (MRI), pharmacokinetic modeling allows estimating quantitative parameters related to the physiology underlying tumor angiogenesis. In particular, novel magnetic resonance dispersion imaging (MRDI) enables quantitative assessment of the microvascular architecture and leakage, by describing the intravascular dispersion kinetics of an extravascular contrast agent with a dispersion model. According to this model, the tissue contrast concentration at each voxel is given by the convolution between the intravascular concentration, described as a Brownian motion process according to the convective-dispersion equation, with the interstitium impulse response, represented by a mono-exponential decay, and describing the contrast leakage in the extravascular space. In this work, an improved formulation of the MRDI method is obtained by providing an analytical solution for the convolution integral present in the dispersion model. The performance of the proposed method was evaluated by means of dedicated simulations in terms of estimation accuracy, precision, and computation time. Moreover, a preliminary clinical validation was carried out in five patients with proven PCa. The proposed method allows for a reduction by about 40% of computation time without any significant change in estimation accuracy and precision, and in the clinical performance.

Dynamic contrast-enhanced MRI in patients with luminal Crohn's disease.

OBJECTIVES: To prospectively assess dynamic contrast-enhanced (DCE-)MRI as compared to conventional sequences in patients with luminal Crohn's disease. METHODS: Patients with Crohn's disease undergoing MRI and ileocolonoscopy within 1 month had DCE-MRI (3T) during intravenous contrast injection of gadobutrol, single shot fast spin echo sequence and 3D T1-weighted spoiled gradient echo sequence, a dynamic coronal 3D T1-weighted fast spoiled gradient were performed before and after gadobutrol. Maximum enhancement (ME) and initial slope of increase (ISI) were calculated for four colon segments (ascending colon+coecum, transverse colon, descending colon+sigmoid, rectum) and (neo)terminal ileum. C-reactive protein (CRP), Crohn's disease activity index (CDAI), per patient and per segment Crohn's disease endoscopic index of severity (CDEIS) and disease duration were determined. Mean values of the (DCE-)MRI parameters in each segment from each patient were compared between four disease activity groups (normal mucosa, non-ulcerative lesions, mild ulcerative and severe ulcerative disease) with Mann-Whitney test with Bonferroni adjustment. Spearman correlation coefficients were calculated for continuous variables. RESULTS: Thirty-three patients were included (mean age 37 years; 23 females, median CDEIS 4.4). ME and ISI correlated weakly with segmental CDEIS (r=0.485 and r=0.206) and ME per patient correlated moderately with CDEIS (r=0.551). ME was significantly higher in segments with mild (0.378) or severe (0.388) ulcerative disease compared to normal mucosa (0.304) (p<0.001). No ulcerations were identified at conventional sequences. ME correlated with disease duration in diseased segments (r=0.492), not with CDAI and CRP. CONCLUSIONS: DCE-MRI can be used as a method for detecting Crohn's disease ulcerative lesions.

Computational modeling for assessment of IBD: to be or not to be?

The grading of inflammatory bowel disease (IBD) severity is important to determine the proper treatment strategy and to quantify the response to treatment. Traditionally, ileocolonoscopy is considered the reference standard for assessment of IBD. However, the procedure is invasive and requires extensive bowel preparation. Magnetic resonance imaging (MRI) has become an important tool for determining the presence of disease activity. Unfortunately, only moderate interobserver agreement is reported for most of the radiological severity measures. There is a clear demand for automated evaluation of MR images in Crohn's disease (CD). This paper aims to introduce a preliminary suite of fundamental tools for assessment of CD severity. It involves procedures for image analysis, classification and visualization to predict the colonoscopy disease scores.

MR spectroscopy findings in early stages of motor neuron disease.

BACKGROUND AND PURPOSE: Upper motor neuron degeneration varies in different phenotypes of MND. We used single-voxel MR spectroscopy of the primary motor cortex to detect corticomotoneuron degeneration and glial hyperactivity in different phenotypes of MND with a relatively short disease duration, contributing to further delineation of the phenotypes. MATERIALS AND METHODS: We prospectively included patients with ALS-B, ALS-L, and PMA and compared their data with those of patients with PLS and healthy controls. Each cohort consisted of 12 individuals. Disease duration was <1 year in ALS and PMA, but longer in PLS by definition. Follow-up examination was at 6 months. We measured ALSFRS-R, finger- and foot-tapping speed, and levels of the following: 1) NAAx, 2) mIns, and 3) Glx in the primary motor cortex. RESULTS: At baseline, we found significantly decreased NAAx levels and increased mIns levels in PLS. Levels of NAAx and mIns in patients with ALS-L and ALS-B were not significantly different from those in controls, but NAAx levels were significantly lower compared with those in PMA. At follow-up, only in PMA was a decrease of NAAx demonstrated. Glx levels varied widely in all groups. Levels of NAAx and mIns correlated well with clinical variables. CONCLUSIONS: Metabolite changes suggest neuronal dysfunction and active glial involvement in PLS. The corticomotoneuron is affected in early ALS-B and ALS-L, but at a later stage also in PMA. MR spectroscopy data are useful to obtain insight into the disease process at the level of the upper motor neuron in various phenotypes of MND.

Hepatic unsaturated fatty acids in patients with non-alcoholic fatty liver disease assessed by 3.0T MR spectroscopy.

RATIONALE AND OBJECTIVE: Non-alcoholic fatty liver disease (NAFLD) is related to the metabolic syndrome and obesity. Proton magnetic resonance spectroscopy ((1)H MRS) is a non-invasive technique to assess hepatic triglyceride content (HTGC) and allows assessment of unsaturated fatty acids (UFA). There is increasing evidence that hepatic UFA are associated with the development of NAFLD. Therefore the objective of this study was to assess hepatic UFA in patients with NAFLD using (1)H MRS. MATERIALS AND METHODS: We included 26 consecutive patients with deranged liver enzymes, with and without type 2 diabetes mellitus (DM2), suspected for NAFLD. Liver function and metabolic parameters were assessed. (1)H MRS measurements were performed at 3.0T. From the (1)H MR spectra two ratios were calculated: ratio 1 (UFA); unsaturated fatty acid peak vs. reference water peak and ratio 2 (HTGC); total fatty acid peak vs. reference water peak. RESULTS: Twenty-six patients were included. In these patients hepatic UFA (ratio 1) correlated with AST/ALT ratio (r=-0.46, p=0.02), glucose levels (r=0.46, p=0.018), HOMA-IR (r=0.59, p=0.004) and HTGC (r=0.81, p<0.001). In diabetic patients (n=12) hepatic UFA correlated with alkaline phosphatase levels (r=0.72, p=0.01), HOMA-IR (r=0.73, p=0.01) and HTGC (r=0.83, p=0.002). Compared to non-diabetic patients with NAFLD, hepatic UFA levels were increased in patients with DM2 and NAFLD (0.032 vs. 0.014, p=0.03). CONCLUSION: Hepatic UFA can be assessed with (1)H MRS. (1)H MRS determined hepatic UFA correlate with clinical and metabolic parameters associated with NAFLD. Hepatic UFA are increased in patients with DM2. This study provides evidence for the use of non-invasive (1)H MRS to assess hepatic UFA in vivo.

Bevacizumab and dose-intense temozolomide in recurrent high-grade glioma.

BACKGROUND: Angiogenesis inhibition is a rational treatment strategy for high-grade glioma (HGG). Combined antiangiogenic therapy and chemotherapy could be beneficial, taking advantage of different mechanisms of antitumour activity of both therapies. We carried out a phase I-II clinical trial with the combination of bevacizumab and continuous dose-intense temozolomide (TMZ) for patients with a recurrent HGG after first- or second-line treatment. PATIENTS AND METHODS: Twenty-three HGG patients were treated with bevacizumab (10 mg/kg i.v. every 3 weeks) and TMZ (daily 50 mg/m(2)), until clinical or radiological progression. Conventional and dynamic magnetic resonance imaging (MRI) were carried out on days -4, 3 and 21 and until clinical or radiological progression. RESULTS: Overall response rate (20%), 6-month progression-free survival (PFS6) (17.4%), median progression-free survival (13.9 weeks) and median overall survival (OS) (17.1 weeks) were considerably lower compared with most other studies with bevacizumab-containing regimens. The dynamic MRI parameters contrast transfer coefficient and relative cerebral blood volume decreased rapidly during the early phases of treatment, reflecting changes in vascularisation and vessel permeability but not in tumour activity. In addition, >50% of patients showed oedema reduction and a reduced shift on T1 images. CONCLUSION: Treatment with bevacizumab and TMZ is feasible and well tolerated but did not improve PFS6 and median OS.

Acquisition time and reproducibility of continuous arterial spin-labeling perfusion imaging at 3T.

Arterial spin-labeling (ASL) is a relatively new and noninvasive MR imaging technique, used to measure cerebral blood flow (CBF). Scanning time and reproducibility remain important issues in the clinical applicability of ASL. We expected both to benefit from higher field strengths. We describe that when performing ASL at 3T, 20 averages suffice to obtain steady and reproducible CBF values. Scanning time can be as short as 3 minutes.

Long-term 3T MR angiography follow-up after therapeutic occlusion of the internal carotid artery to detect possible de novo aneurysm formation.

BACKGROUND AND PURPOSE: The purpose of this study was to assess the incidence of de novo aneurysm formation, the incidence of subarachnoid hemorrhage (SAH), and the growth of existing untreated aneurysms in 52 patients after therapeutic carotid artery balloon occlusion for carotid aneurysms. PATIENTS AND METHODS: Between January 1996 and August 2004, 52 patients were treated with carotid artery balloon occlusion for carotid aneurysms. In June 2005, all patients, their next of kin, or family physicians were contacted and questioned concerning episodes of headache or hospital admissions that could be attributed to SAH. In addition, MR imaging and MR angiography (MRA) at 3T were performed in 26 of 44 surviving patients after a mean follow-up period of 50.2 months (median, 43.5 months; range, 14-107 months). MR imaging and MRA studies were compared with the digital subtraction angiograms at the time of carotid artery occlusion. RESULTS: During clinical follow-up of 52 patients at a mean of 50.3 months (median, 42.5 months; range, 0-107 months), no episodes of SAH were reported (0%; 97.5% confidence interval [CI], 0-8.2%). In the 26 patients with follow-up MR imaging, no de novo aneurysms were detected (0%; 97.5 CI, 0-13.2%). Five existing untreated small aneurysms in 5 patients had not enlarged after a mean follow-up of 40 months. CONCLUSION: In this study, therapeutic carotid artery occlusion was not associated with development of new aneurysms or enlargement of existing untreated aneurysms with time.

Thyroid abscess associated with a substernal goiter. Case report.

An abscess associated with an intrathoracic goiter is an extremely rare condition. The authors report a case of a thyroid abscess complicated by acute dyspnea and asphyxia in a patient of geriatric age with a substernal goiter. Surgical therapy was necessary to obtain a correct diagnosis and an effective treatment.

Descending necrotizing mediastinitis. Diagnosis and surgical treatment.

AIM: Descending necrotizing mediastinitis (DNM) is an unusual and severe disease with a high mortality rate. Surgical management remains controversial. Our investigations reviews the most effective surgical treatment in the management of this rare pathology. METHODS: Seven patients with DNM and treated over a 20-year period are reported. All patients were evaluated according to the classification suggested by Endo et al. of the degree of mediastinal diffusion, based on CT scan findings. Five patients underwent combined cervical drainage and thoracotomy, 2 patients were treated with cervical drainage alone. RESULTS: The outcome was favorable in 5 patients, 4 treated with a combined cervical and thoracic approach and 1 with a cervical approach alone. Two patients that underwent a combinated cervical and thoracic approach alone, died of septic shock. Overall mortality rate was 28.5%. CONCLUSION: Early diagnosis and early, aggressive surgical treatment are required to improve the poor prognosis of DNM. Although a unique surgical management is still not completely accepted, we state, in agreement with other authors, a wide approach consisting of a cervical drainage and mediastinotomy in case of upper mediastinitis and a combined cervical and thoracic approach in case of lower mediastinitis. In the course of thoracotomy a wide excision of necrotic and particularly fat mediastinal tissue is needed, to avoid a recurrent infection. A continuous cervico-mediastinal irrigation system is suggested during the postoperative period.

Intravenous delivery of hyperpolarized (129)Xe: a compartmental model.

There is an increasing interest in the use of hyperpolarized 129-xenon (HpXe) NMR for the measurement of tissue perfusion. In this paper we present a theoretical study designed to assess the merit of intravenous HpXe delivery compared with the existing respiration techniques. A compartmental model was created to describe the behavior of the injected bolus in the circulatory system and in the lungs. The dependence of the tissue concentration on the T(1) and solubility of the Xe in the various compartments, and on injection rate, were evaluated. By this process the critical loss mechanisms are identified. It is shown that the predicted tissue concentrations of HpXe in gray and white matter are comparable using respiration or injection techniques.

High-resolution segmented EPI in a motor task fMRI study.

A high-resolution gradient echo, multi-slice segmented echo planar imaging method was used for functional MRI (fMRI) using a motor task at 1.5 Tesla. Functional images with an in-plane resolution of 1 mm and slice thickness of 4 mm were obtained with good white-gray matter contrast. The multi-shot approach, combined with a short total readout period of 82 ms, limits blurring effects for short T(2)(*) tissues (such as gray matter), assuring truly high-resolution images. In all subjects, motor functions were clearly depicted in the contralateral central sulcus over several slices and sometimes activation was detected in the supplementary motor area and/or ipsilateral central sulcus. The average signal change of 11+/-3% was much higher than in standard low-resolution fMRI EPI experiments, as a result of larger relative blood fractions.