Does higher gadolinium concentration play a role in the morphologic assessment of brain tumors? Results of a multicenter intraindividual crossover comparison of gadobutrol versus gadobenate dimeglumine (the MERIT Study)

BACKGROUND AND PURPOSE

Gadobenate dimeglumine has proved advantageous compared with other gadolinium-based contrast agents for contrast-enhanced brain MR imaging. Gadobutrol is a more highly concentrated agent (1.0 mol/L). This study intraindividually compared 0.1-mmol/kg doses of these agents for qualitative and quantitative evaluation of brain tumors.

MATERIALS AND METHODS

Adult patients with suspected or known brain tumors underwent 2 identical MR imaging examinations at 1.5T, 1 with gadobenate dimeglumine and the other with gadobutrol, both at a dose of 0.1-mmol/kg body weight. The agents were injected in randomized order separated by 3-14 days. Imaging sequences and acquisition timing were identical for the 2 examinations. Three blinded readers evaluated images qualitatively for diagnostic information (lesion extent, delineation, morphology, enhancement, global preference) and quantitatively for CNR and LBR.

RESULTS

One hundred fourteen of 123 enrolled patients successfully underwent both examinations. Final diagnoses were intra-axial tumors, metastases, extra-axial tumors, "other" tumors, and "nontumor" (49, 46, 8, 7, and 4 subjects, respectively). Readers 1, 2, and 3 demonstrated preference for gadobenate dimeglumine in 46 (40.7%), 54 (47.4%), and 49 (43.0%) patients, respectively, compared with 6, 7, and 7 patients for gadobutrol (P < .0001, all readers). Highly significant (P < .0001, all readers) preference for gadobenate dimeglumine was demonstrated for all other qualitative end points. Inter-reader agreement was good for all evaluations (κ = 0.414-0.629). Significantly superior CNR and LBR were determined for gadobenate dimeglumine (P < .019, all readers).

CONCLUSIONS

Significantly greater morphologic information and lesion enhancement are achieved on brain MR imaging with 0.1-mmol/kg gadobenate dimeglumine compared with gadobutrol at an equivalent dose.

A systems approach towards intra-arterial management of acute ischemic stroke: need for novel outcome measures and a focus on sequence rather than steps

In this editorial, we seek to focus attention of neurointerventionists and stroke physicians towards a systems approach to the intra-arterial management of acute ischemic stroke. We highlight the need to pay attention to the overall sequence and workflow of a neurointerventional procedure rather than individual steps. We also stress the importance of novel outcome measures in analyzing procedural efficacy when managing patients with acute ischemic stroke.

Regional leptomeningeal score on CT angiography predicts clinical and imaging outcomes in patients with acute anterior circulation occlusions

BACKGROUND AND PURPOSE

The regional leptomeningeal score is a strong and reliable imaging predictor of good clinical outcomes in acute anterior circulation ischemic strokes and can therefore be used for imaging based patient selection. Efforts to determine biological determinants of collateral status are needed if techniques to alter collateral behavior and extend time windows are to succeed.

MATERIALS AND METHODS

This was a retrospective Institutional Review Board-approved study of patients with acute ischemic stroke and M1 middle cerebral artery+/- intracranial internal carotid artery occlusion at our center from 2003 to 2009. The rLMC score is based on scoring pial and lenticulostriate arteries (0, no; 1, less; 2, equal or more prominent compared with matching region in opposite hemisphere) in 6 ASPECTS regions (M1-6) plus anterior cerebral artery region and basal ganglia. Pial arteries in the Sylvian sulcus are scored 0, 2, or 4. Good clinical outcome was defined as mRS ≤ 2 at 90 days.

RESULTS

The analysis included 138 patients: 37.6% had a good (17-20), 40.5% a medium (11-16), and 21.7% a poor (0-10) rLMC score. Interrater reliability was high, with an intraclass correlation coefficient of 0.87 (95% CI, 0.77%-0.95%). On univariate analysis, no single vascular risk factor was associated with the presence of poor rLMCs (P ≥ .20 for all comparisons). In multivariable analysis, the rLMC score (good versus poor: OR, 16.7; 95% CI, 2.9%-97.4%; medium versus poor: OR, 9.2, 95% CI, 1.7%-50.6%), age (< 80 years), baseline ASPECTS (≥ 8), and clot burden score (≥ 8) were independent predictors of good clinical outcome.

CONCLUSIONS

The rLMC score is a strong imaging parameter on CT angiography for predicting clinical outcomes in patients with acute ischemic strokes.

Achieving faster recanalization times by IA thrombolysis in acute ischemic stroke: where should we direct our efforts?

Faster recanalization correlates with better outcomes in acute ischemic stroke. We analyzed times from arrival in ER to end of treatment in patients undergoing endovascular treatment for acute ischemic stroke at our institution.We retrospectively studied patients who underwent IA procedures for stroke from 2005 to 2009 noting the times of arrival to ER, CT scan, arrival to DSA, arterial puncture and recanalization from our endovascular database. A subgroup analysis was performed based on administration of GA, use of mechanical devices and whether the procedure was performed during regular hours or after hours.Of 101 patients, 53 were male, with a median age of 66 years (range 18-87). There were 81 anterior circulation strokes. Median ER to CT time was 22 min (2-1025), CT to DSA arrival time 80 min (range 4-990), DSA arrival to puncture time 24 min (range 0-75) and puncture to recanalization time 84 min (range 11-206). 23.3% of patients had an ER to CT time interval of > 60 min and 71.3 % had a CT to DSA time interval of > 60 min contributing to significant in-hospital delays. For subgroup analysis the Mann-Whitney test was used. No significant differences in CT to DSA arrival (p=0.8), DSA arrival to puncture (p=0.1) and puncture to recanalization (p=0.59) times were noted between patients with and without GA. No significant difference was noted in puncture to recanalization times with or without device (p=0.78). 39 cases were done during regular (R) hours and 62 after (A) hours. Median ER to CT time (R=18 min, A = 27 min, p 0.02), CT to DSA arrival time (R=64 min, A=90 min, p 0.004) and DSA arrival to puncture time (R=18 min, A=25 min, p 0.003) was significantly higher after hours.ER to CT and CT to DSA arrival times in patients undergoing endovascular stroke therapy show wide variability and therefore, considerable scope for reduction. Time differences during regular and after hours should serve as a reminder to make efforts to reduce overall ischemic times in spite of staffing patterns and resource availability.

Structural transformations in CdSe nanoparticles: density functional theory approach

This paper addresses the multidimensional effects related with structural transformations of CdSe nanoparticles to human health and environment. The nanoparticles do undergo a wurtzite to rock salt transition that is analogous to that observed in bulk CdSe, it was observed that the limited extent of the crystallites affects both the thermodynamics and kinetics of the transition. The study reveals that the nanoparticles if suitably modified can be useful for biomedical applications.

Balloon-assisted rapid intermittent sequential coiling (BRISC) technique for the treatment of complex wide-necked intracranial aneurysms

We describe our experience with balloon-assisted rapid intermittent sequential coiling (BRISC) of complex wide-necked aneurysms as an alternative to stent-assisted coiling. We use this technique in patients with acutely ruptured aneurysms, where antithrombotic treatment prior to stent deployment may not be advisable, and where the vascular anatomy is unfavorable for stenting. This is a retrospective analysis of 11 wide-necked aneurysms treated with this technique from June 2008 to January 2010. Results were analyzed in terms of aneurysm occlusion, procedural complications like thromboembolism, dissection/vasospasm, groin hematoma and any recurrence on follow-up. Coiling was successfully attempted in all cases (100%). Immediate angiographic results showed complete occlusion (class 1) in 8/11, residual neck (class II) in 3/11 and no residual aneurysm (class III). Procedural complications were local thrombus formation in 3/11 procedures but no symptomatic thromboembolism, dissection in 1/11 and groin hematoma in 1/11. There was no morbidity or mortality. On follow-up study, there was one recurrence, which was subsequently coiled. In our opinion, this technique may provide an alternative to stent-assisted coiling in patients with ruptured aneurysm where antithrombotic treatment prior to stent deployment may not be advisable and in the presence of vascular anatomy unsuitable for stenting.

Fusiform lenticulostriate artery aneurysm with subarachnoid hemorrhage: the role for superselective angiography in treatment planning

Aneurysms of the lenticulostriatal perforating arteries are rare and either involve the middle cerebral artery-perforator junction or are located distally in basal ganglia. We describe a rare ruptured fusiform lenticulostriatal perforating artery aneurysm arising from a proximal M2 MCA branch, discerned on superselective microcatheter angiography, presenting solely with subarachnoid hemorrhage (SAH). A 50-year-old previously healthy man presented with diffuse SAH and negative CT angiogram. Cerebral angiogram demonstrated a 2 mm fusiform aneurysm presumably arising from the right lateral lenticulostriate perforator but the exact origin of the perforator was unclear. Superselective angiography was required to precisely delineate the aneurysm and its vessel of origin and directly influenced treatment planning (surgical trapping). Superselective microcatheter angiography provides both an option for endovascular therapy as well as more accurate delineation for surgical planning for these rare aneurysms.

Treatment of acute ischemic stroke: awareness among general practitioners

For promptly referral of a patient with acute ischemic stroke (AIS) for possible thrombolysis, general practitioners (GPs) need to equipped with the advanced knowledge of AIS treatment. We assessed the knowledge regarding treatment of AIS among GPs practicing in and around a quaternary care teaching hospital in south India. A total of 109 GPs who attend to medical emergencies were interviewed using a standard questionnaire. Of the 109 GPs interviewed, 54% felt that tissue plasminogen activator (tPA) can be used in the treating AIS, but only 24% had chosen tPA as the best treatment option and 22% opted for other agents like citicholine or edavarone. Only 17% were aware that tPA should be given within 3 h. and 35% felt that intra-arterial thrombolysis as a treatment option.. Only 30% felt the need for good sugar control and 37% wanted aggressive lowering of blood pressure. Majority of GPs are not clear about beneficial effects of thrombolysis and are not updated regarding BP and sugar control in the setting of AIS.

Time dependent expression of cytokines in Mycobacterium bovis infected cattle lymph nodes

Advancements in the current diagnostic and vaccination protocols employed against bovine tuberculosis rely heavily upon a sound knowledge of the bovine immunological response. Central to this is the importance of timing in the cellular immune profile and how this dynamic process evolves post-Mycobacterium bovis challenge. In the present study, we quantitatively analysed mRNA expression of interferon gamma (IFN-γ), tumour necrosis factor alpha (TNF-α) and interleukins (IL) 4 and 10 within select thoracic lymph nodes of cattle infected with M. bovis for 5, 12 and 19 weeks as compared to non-infected bovine tissues. The M. bovis infected lymph nodes displayed significantly higher expression levels of IFN-γ and TNF-α as compared to the non-infected lymph node tissues. This, in conjunction with undetectable levels of IL4, suggests a pro-inflammatory cytokine response. However a significant increase was also detected in IL10 mRNA which is consistent with a described aspect of T(H)1 type T cells in Leishmania infection, a 'self-limiting' process in which cells produced both IFN-γ and IL10 with the aim of controlling the heightened immunopathological responses. This was further reflected when comparing the cytokine profiles of the individual lymph node types, as those displaying a higher IFN-γ/IL10 ratio also had a greater level of gross pathology. This data highlights the important role of IL10 in the bovine response to M. bovis infection and supports its involvement as an immunological marker of disease progression.

Nasal spirometery

Nasal obstruction is a common symptom which is difficult to quantify clinically. Rhinomanometry, Acoustic Rhinometry and Forced Oscillation methods are available for estimating nasal resistance but, these require sophisticated machines. Because of limited availability of these techniques, this potential physiological measure has not been tapped fully for research and clinical purposes. Here, we describe the use of pulmonary spirometer with little modification for quantification of nasal flow. Nasal inspiratory and expiratory flow rates along with oral inspiratory and expiratory flow rates are used to derive different nasal resistance indices. This way of reporting nasal resistance is not new but, the data for these variables is currently not available in published literature. The reproducibility of nasal flow rates were tested as variation after one day and the interclass coefficient for inspiratory and expiratory nasal flow rates were found to be with in acceptable limits. Thus, nasal spirometery is able to describe the nasal resistance in a reliable manner and may be used to quantify nasal obstruction in pathological condition and also to study the physiological phenomenon like nasal cycle.

Individuals with mutations in XPNPEP3, which encodes a mitochondrial protein, develop a nephronophthisis-like nephropathy

The autosomal recessive kidney disease nephronophthisis (NPHP) constitutes the most frequent genetic cause of terminal renal failure in the first 3 decades of life. Ten causative genes (NPHP1-NPHP9 and NPHP11), whose products localize to the primary cilia-centrosome complex, support the unifying concept that cystic kidney diseases are "ciliopathies". Using genome-wide homozygosity mapping, we report here what we believe to be a new locus (NPHP-like 1 [NPHPL1]) for an NPHP-like nephropathy. In 2 families with an NPHP-like phenotype, we detected homozygous frameshift and splice-site mutations, respectively, in the X-prolyl aminopeptidase 3 (XPNPEP3) gene. In contrast to all known NPHP proteins, XPNPEP3 localizes to mitochondria of renal cells. However, in vivo analyses also revealed a likely cilia-related function; suppression of zebrafish xpnpep3 phenocopied the developmental phenotypes of ciliopathy morphants, and this effect was rescued by human XPNPEP3 that was devoid of a mitochondrial localization signal. Consistent with a role for XPNPEP3 in ciliary function, several ciliary cystogenic proteins were found to be XPNPEP3 substrates, for which resistance to N-terminal proline cleavage resulted in attenuated protein function in vivo in zebrafish. Our data highlight an emerging link between mitochondria and ciliary dysfunction, and suggest that further understanding the enzymatic activity and substrates of XPNPEP3 will illuminate novel cystogenic pathways.

NFkappaB promotes inflammation, coagulation, and fibrosis in the aging glomerulus

The peak prevalence of ESRD from glomerulosclerosis occurs at 70 to 79 years. To understand why old glomeruli are prone to failure, we analyzed the Fischer 344 rat model of aging under ad libitum-fed (rapid aging) and calorie-restricted (slowed aging) conditions. All glomerular cells contained genes whose expression changed "linearly" during adult life from 2 to 24 months: mesangial cells (e.g., MMP9), endothelial cells (e.g., ICAM and VCAM), parietal epithelial cells (e.g., ceruloplasmin), and podocytes (e.g., nephrin and prepronociceptin). Patterns of aging glomerular gene expression closely resembled atherosclerosis, including activation of endothelial cells, epithelial cells, and macrophages, as well as proinflammatory pathways related to cell adhesion, chemotaxis, blood coagulation, oxidoreductases, matrix metalloproteinases, and TGF-beta activation. We used a nonbiased data-mining approach to identify NFkappaB as the likely transcriptional regulator of these events. We confirmed NFkappaB activation by two independent methods: translocation of NFkappaB p50 to glomerular nuclei and ChIP assays demonstrating NFkappaB p50 binding to the kappaB motif of target genes in old versus young glomeruli. These data suggest that old glomeruli exhibit NFkappaB-associated up-regulation of a proinflammatory, procoagulable, and profibrotic phenotype compared with young glomeruli; these distinctions could explain their enhanced susceptibility to failure. Furthermore, these results provide a potential mechanistic explanation for the close relationship between ESRD and atherosclerotic organ failure as two parallel arms of age-associated NFkappaB-driven processes.

Antibodies to protein tyrosine phosphatase receptor type O (PTPro) increase glomerular albumin permeability (P(alb))

Glomerular capillary filtration barrier characteristics are determined in part by the slit-pore junctions of glomerular podocytes. Protein tyrosine phosphatase receptor-O (PTPro) is a transmembrane protein expressed on the apical surface of podocyte foot processes. Tyrosine phosphorylation of podocyte proteins including nephrin may control the filtration barrier. To determine whether PTPro activity is required to maintain glomerular macromolecular permeability, albumin permeability (P(alb)) was studied after incubation of glomeruli from normal animals with a series of monoclonal (mAb) and polyclonal antibodies. Reagents included mAbs to rabbit and rat PTPro and polyclonal rabbit immune IgG to rat PTPro. mAb 4C3, specific to the amino acid core of PTPro, decreased its phosphatase activity and increased P(alb) of rabbit glomeruli in a time- and concentration-dependent manner. In contrast, mAb P8E7 did not diminish phosphatase activity and did not alter P(alb). Preincubation of 4C3 with PTPro extracellular domain fusion protein blocked glomerular binding and abolished permeability activity. In parallel experiments, P(alb) of rat glomeruli was increased by two mAbs (1B4 and 1D1) or by polyclonal anti-rat PTPro. We conclude that PTPro interaction with specific antibodies acutely increases P(alb). The identity of the normal ligand for PTPro and of its substrate, as well as the mechanism by which phosphatase activity of this receptor affects the filtration barrier, remain to be determined.

Urine podocyte mRNAs mark progression of renal disease

Because loss of podocytes associates with glomerulosclerosis, monitoring podocyte loss by measuring podocyte products in urine may be clinically useful. To determine whether a single episode of podocyte injury would cause persistent podocyte loss, we induced limited podocyte depletion using a diphtheria toxin receptor (hDTR) transgenic rat. We monitored podocyte loss by detecting nephrin and podocin mRNA in urine particulates with quantitative reverse transcriptase-PCR. Aquaporin 2 mRNA served as a kidney reference gene to account for variable kidney contribution to RNA amount and quality. We found that a single injection of diphtheria toxin resulted in an initial peak of proteinuria and podocyte mRNAs (podocin and nephrin) followed 8 d later by a second peak of proteinuria and podocyte mRNAs that were podocin positive but nephrin negative. Proteinuria that persisted for months correlated with podocin-positive, nephrin-negative mRNAs in urine. Animals with persistent podocyte mRNA in urine progressed to ESRD with global podocyte depletion and interstitial scarring. Podocytes in ectatic tubules expressed podocalyxin and podocin proteins but not nephrin, compatible with detached podocytes' having an altered phenotype. Parallel human studies showed that biopsy-proven glomerular injury associated with increased urinary podocin:aquaporin 2 and nephrin:aquaporin 2 molar ratios. We conclude that a single episode of podocyte injury can trigger glomerular destabilization, resulting in persistent podocyte loss and an altered phenotype of podocytes recovered from urine. Podocyte mRNAs in urine may be a useful clinical tool for the diagnosis and monitoring of glomerular diseases.