Arterial spin labeling at 3.0 Tesla in subacute ischemia: comparison to dynamic susceptibility perfusion

PURPOSE

Arterial spin labeling (ASL) is a promising but clinically not established non-invasive method to assess cerebral perfusion. The purpose of this study was to compare perfusion imaging with pulsed ASL (pASL) to conventional dynamic susceptibility contrast (DSC) perfusion-weighted imaging (PWL) using commercially available equipment and postprocessing (3.0 Tesla, 32-channel head coil) in patients with subacute ischemia.

METHODS

The pASL and DSC-PWI techniques were compared in 15 patients with subacute ischemia (age 49-88 years, 6 females and 9 males, time from onset to scan 4-161 h). Image inhomogeneity was assessed with the non-uniformity index. Image quality, delineation of hypoperfusion and degree of hypoperfusion were rated by two readers using a 5-scale grading system. The volume of hypoperfusion was quantified planimetrically.

RESULTS

Image quality and image inhomogeneity were superior in DSC time-to-peak (TTP) compared to pASL cerebral brain flow (CBF; both p < 0.05). The delineation of hypoperfusion was better in DSC-TTP (p < 0.05) and the hypoperfusion was graded as more severe in DSC-TTP (p < 0.05). The volume of hypoperfusion did not differ between pASL-CBF and DSC-TTP, however, in pASL-CBF five cases with small infarctions (lacunar and pontine) were false negative compared to DSC-relative CBF. The mismatch frequency was lower in pASL (13%) than in DSC-rCBF (20%) and DSC-TTP (47%).

CONCLUSIONS

Using a commercially available sequence and a 32-channel head coil at 3.0 Tesla pASL-CBF is feasible but limited compared to DSC-PWI in the assessment of ischemic stroke. In its present form pASL has a reserve role in clinical practice for situations when gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) is contraindicated.

Bilateral symmetrical cortical osteolytic lesions in two patients with Gaucher disease

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder characterized by the reduced or absent activity of glucocerebrosidase. The disease is split into three types. Type 3, or chronic neuronopathic GD, manifests with heterogeneous clinical presentations. Skeletal manifestations of GD can include abnormal bone remodeling resulting in the characteristic Erlenmeyer flask deformities, painful bone crises, osteopenia, and an increased frequency of fractures. Osteolytic lesions can also occur but are rare and tend to be large, expanding intramedullary lesions with cortical thinning. We present two adolescent patients with type 3 GD who developed bilateral symmetrical cortical osteolytic lesions. The lesions in both cases demonstrate predominant cortical scalloping with fairly indolent growth. Neither patient manifests some of the more common bony manifestations of GD--bone crises or osteonecrosis. These atypical and unique skeletal findings in two unrelated probands with type 3 GD further expand the extent of phenotypic variation encountered in this single gene disorder.

TrueFISP of the pediatric pineal gland: volumetric and microstructural analysis

PURPOSE

Although high-resolution 3D-imaging has markedly improved the imaging of the pediatric pineal gland, the prevalences of typical and atypical cysts as well as in vivo volumes are unknown. The purpose of this study was to compare the frequency of typical and atypical cysts using high-resolution 3D-sequence true fast imaging with steady state precession (trueFISP) and standard sequences and to directly measure the pineal volume in a large pediatric population.

METHODS

In 54 consecutively examined children (age 0-17 years, mean age 5.4 ± 5.6 years, 44% female, 56% male) the prevalence of typical and atypical cysts (thickened rim, trabeculations, asymmetry) was determined using trueFISP (isotropic, 0.8 mm) and standard sequences, 1.5-T, T1-weighted spin echo (T1-SE), T2-weighted turbo spin echo (T2-TSE) and fluid attenuated inversion recovery (FLAIR). Indistinct findings were noted separately. Volumetry was based on the trueFISP datasets. Solid and cystic compartments were approached separately. The pineal volume was correlated to gender and age.

RESULTS

The detected frequency of pineal cysts was higher in trueFISP (57.4%) than in standard sequences (T1-SE 7.4%, T2-TSE 14.8%, and FLAIR 13.0%). In trueFISP 66.3% of the detected cysts were classified as atypical (standard sequences 0%). Indistinct findings were lowest in trueFISP. The mean pineal volume was 94.3 ± 159.1 mm³ and no gender related differences were found. Age and volume showed a moderate correlation (r = 0.382) which was remarkably higher in completely solid glands (r = 0.659).

CONCLUSIONS

TrueFISP imaging improves the detection of pineal cysts in children. A typical cysts are frequently detected as an incidental finding. Volumetric analysis of the pediatric pineal gland is feasible and reveals enormous variation. Whereas gender effects are negligible, the pineal volume in children is dependant on age.

Maintained functionality of an implantable radiotelemetric blood pressure and heart rate sensor after magnetic resonance imaging in rats

Radiotelemetric sensors for in vivo assessment of blood pressure and heart rate are widely used in animal research. MRI with implanted sensors is regarded as contraindicated as transmitter malfunction and injury of the animal may be caused. Moreover, artefacts are expected to compromise image evaluation. In vitro, the function of a radiotelemetric sensor (TA11PA-C10, Data Sciences International) after exposure to MRI up to 9.4 T was assessed. The magnetic force of the electromagnetic field on the sensor as well as radiofrequency (RF)-induced sensor heating was analysed. Finally, MRI with an implanted sensor was performed in a rat. Imaging artefacts were analysed at 3.0 and 9.4 T ex vivo and in vivo. Transmitted 24 h blood pressure and heart rate were compared before and after MRI to verify the integrity of the telemetric sensor. The function of the sensor was not altered by MRI up to 9.4 T. The maximum force exerted on the sensor was 273 ± 50 mN. RF-induced heating was ruled out. Artefacts impeded the assessment of the abdomen and thorax in a dead rat, but not of the head and neck. MRI with implanted radiotelemetric sensors is feasible in principal. The tested sensor maintains functionality up to 9.4 T. Artefacts hampered abdominal and throacic imaging in rats, while assessment of the head and neck is possible.

[A child's birthday with consequences]

Foreign body ingestion is a common pediatric emergency and if the foreign body cannot be detected radiologically or endoscopically further investigations are required. In this article the case of a radiolucent, ingested foreign body (mini-candleholder of a birthday cake) is presented. The foreign body could not initially be identified via X-ray and endoscopy due to its parapharyngeal localization but was finally visualized by magnetic resonance imaging (MRI) which additionally uncovered the co-existence of acute mediastinal inflammation.

Dual-energy CT after peri-interventional subarachnoid haemorrhage: a feasibility study

PURPOSE

The aim was to assess the feasibility of dual-energy computed tomography (DE-CT) for detection of peri-interventional re-bleeding in patients with aneurysmal subarachnoid hemorrhage (re-SAH).

METHODS

For in vitro-analyses DE-CT of partially clotted blood intermixed with fresh blood containing contrast agent was performed. In a clinical setting, 4 patients routinely underwent DE-CT after suspected peri-interventional re-SAH. DE-CT source data images, iodine maps and virtual non-contrast images (VNC) were analyzed and regions-of-interest (ROI) measurements of density values were performed.

RESULTS

In vitro experiments demonstrated the feasibility of DE-CT to discriminate between blood with and without contrast agent. In all patients peri-interventional re-SAH was confirmed by detection of extravasated iodine within the subarachnoid spaces in post-interventional DE-CT. Dual-energy CT allowed the discrimination of old blood clots of the initial SAH and blood originating from peri-interventional re-SAH. After subtraction of the iodine-related high density signal, VNC images optimized the estimation of the true amount of subarachnoid blood.

CONCLUSION

Dual-energy CT allows the discrimination and subtraction of blood and iodine mixed within the subarachnoid spaces in patients with peri-interventional re-SAH. It helps to avoid overestimation of SAH after peri-interventional re-bleeding and therefore is a potentially valuable tool in the assessment of peri-interventional re-SAH.

[Current concepts for experimental micro-CT in small animals]

The number of publications describing the use of micro-computed tomography (microCT) for preclinical in vivo imaging of small animals has risen considerably within the last few years. The purpose of this review is to familiarize the reader with the basic principles of microCT, to present successful experimental approaches in order of the evaluated organ system, and to highlight limitations that need to be considered when planning microCT-based studies.

Successful granulocyte-colony stimulating factor treatment of Crohn's disease is associated with the appearance of circulating interleukin-10-producing T cells and increased lamina propria plasmacytoid dendritic cells

Granulocyte-colony stimulating factor (G-CSF) has proved to be a successful therapy for some patients with Crohn's disease. Given the known ability of G-CSF to exert anti-T helper 1 effects and to induce interleukin (IL)-10-secreting regulatory T cells, we studied whether clinical benefit from G-CSF therapy in active Crohn's disease was associated with decreased inflammatory cytokine production and/or increased regulatory responses. Crohn's patients were treated with G-CSF (5 microg/kg/day subcutaneously) for 4 weeks and changes in cell phenotype, cytokine production and dendritic cell subsets were measured in the peripheral blood and colonic mucosal biopsies using flow cytometry, enzyme-linked immunosorbent assay and immunocytochemistry. Crohn's patients who achieved a clinical response or remission based on the decrease in the Crohn's disease activity index differed from non-responding patients in several important ways: at the end of treatment, responding patients had significantly more CD4(+) memory T cells producing IL-10 in the peripheral blood; they also had a greatly enhanced CD123(+) plasmacytoid dendritic cell infiltration of the lamina propria. Interferon-gamma production capacity was not changed significantly except in non-responders, where it increased. These data show that clinical benefit from G-CSF treatment in Crohn's disease is accompanied by significant induction of IL-10 secreting T cells as well as increases in plasmacytoid dendritic cells in the lamina propria of the inflamed gut mucosa.

Analysis of mouse brain using a clinical 1.5 T scanner and a standard small loop surface coil

With increasing numbers of in vivo experiments in the field of neuroscience, the interest in methods for in vivo imaging of animal brains as small as those of mice has increased. Because highly specialized small bore scanners with high field strengths are not commonly available, clinical magnetic resonance imaging (cMRI) scanners have been used in the past to image rat and more recently also mouse brains in combination with specifically developed RF coils. These studies have demonstrated that imaging of small animal brains is feasible, and that tumor volumes measured by cMRI correlate well with histological tumor volume analysis. This protocol describes the cMRI settings at 1.5 T for imaging of mouse brain with resolutions up to 120 x 120 microm using an inexpensive, commercially available small loop surface coil. This allows easy establishment of a small animal MRI facility without the need for cost intensive dedicated small animal scanners or special custom made coils. In this study, we demonstrate high-resolution imaging of intracranial xenografts in a mouse glioma model and monitor the treatment effect of external field irradiation by cMRI.

Subcortical angiopathic encephalopathy in a German kindred suggests an autosomal dominant disorder distinct from CADASIL

A cerebral arteriopathy with subcortical infarcts and leukoencephalopathy is described with a pedigree suggestive for an autosomal dominant condition. In contrast to the vasculopathy designated with the acronym CADASIL, no deposits of granular osmiophilic material were detected in the vasculature and no point mutations in the NOTCH 3 gene were found. The disease occurred in a family living near Hamburg, Germany, and affected 11 women and 11 men over the last six generations. Onset of the disease was between the age of 12 and 50. Clinical symptoms included gait disturbances, dysarthria, sensomotoric deficits and a progressive dementia. Migraine-like complaints and epileptic seizures were observed in one case each. Cranial computer tomography and magnetic resonance imaging scans showed large confluent areas with decreased density in the white matter and small necroses in the brain stem, the basal ganglia and the white matter. A correlation with factors predisposing for vascular diseases could not be demonstrated. In five cases an autopsy was performed which disclosed an angiopathy affecting predominantly the penetrating arteries with consecutive lacunar infarcts, diffuse demyelination and rarefication of the subcortical white matter and degeneration of the pyramidal tracts. Histologically, the vessels showed concentric and excentric intimal proliferation, an elastosis and hyalinosis, splitting of the lamina elastica interna and a degeneration of the tunica muscularis. Electron microscopy revealed fragmentation and thickening of the basal lamina but electron-dense granules characteristic for CADASIL were not detected.