Phase-sensitive inversion-recovery MR imaging in the detection of myocardial infarction

PURPOSE: To prospectively determine if phase-sensitive inversion-recovery (IR) magnetic resonance (MR) imaging eliminates the need to find the precise inversion time (TI) to null the signal of normal myocardium to achieve high contrast between infarcted and normal myocardium. MATERIALS AND METHODS: Informed consent was obtained from each patient for this prospective MR imaging research study, which was approved by the institutional review board. Twenty patients (16 men; four women; mean age, 56 years +/- 12.3) who experienced Q-wave myocardial infarction 2 weeks earlier were examined with a 1.5-T MR system 10 minutes after administration of 0.1 mmol per kilogram of body weight gadobenate dimeglumine. To determine the optimal TI, a TI scout sequence was used. A segmented two-dimensional IR turbo fast low-angle shot (FLASH) sequence and a segmented two-dimensional IR true fast imaging with steady-state precession (FISP) sequence that produces both phase-sensitive and magnitude-reconstructed images were used at TI values of 200-600 msec (TI values were varied in 100-msec steps) and at optimal TI (mean value, 330 msec). Contrast-to-noise ratios (CNRs) of normal and infarcted myocardium and the area of infarcted myocardium were determined. Magnitude-reconstructed IR turbo FLASH images were compared with magnitude-reconstructed and phase-sensitive IR true FISP images. Two-tailed unpaired sample Student t test was used to compare CNRs, and two-tailed paired-sample Student t test was used to compare area of infarction. RESULTS: Mean CNR of images acquired with IR turbo FLASH and IR true FISP (phase-sensitive and magnitude-reconstructed images) at optimal TI (mean value, 330 msec) were 6.6, 6.2, and 6.1, respectively. For a TI of 200 msec, CNR values were -4.3, -4.0, and 7.2, respectively; for TI of 600 msec, CNR values were 3.1, 3.3, and 4.3, respectively. Area of infarcted myocardium was underestimated on magnitude-reconstruction images (P = .002-.03) for short TI values (ie, 200 msec) for both sequences and for a TI of 300 msec for IR true FISP but not on phase-sensitive reconstructed IR true FISP images when compared with IR turbo FLASH images obtained at optimal TI. CONCLUSION: Phase-sensitive image reconstruction results in reduced need for precise choice of TI and more consistent image quality.     

Role of MRI for the diagnosis and prognosis of multiple myeloma

For the correct staging of patients with multiple myeloma sensitive detection is mandatory in order to estimate prognosis and to decide for adequate therapy. Magnetic resonance imaging (MRI) is superior to radiography for both, focal and diffuse involvement. Five different infiltration patterns can be differentiated: (1) normal appearance of bone marrow despite minor microscopic plasma cell infiltration, (2) focal involvement, (3) homogeneous diffuse infiltration, (4) combined diffuse and focal infiltration, (5) "salt-and-pepper"-pattern with inhomogeneous bone marrow with interposition of fat islands. For the fast and complete assessment of all patterns a combination of a T1-weighted spin echo sequence and a fat suppression technique should be employed. The focal involvement is clearly demonstrated as areas of high signal intensity on, e.g. STIR images. Diffuse involvement is best detected on unenhanced T1-weighted SE sequences and it manifests as homogeneous signal reduction. It can be quantified objectively by calculation of the percentage of signal intensity increase after contrast material injection. With parallel imaging and special coil devices, such as total imaging matrix (Siemens systems, Avanto) a "screening" of the whole red bone marrow as for myeloma infiltration is possible within a reasonable time. Patients without bone marrow infiltration have a significantly longer survival than patients with bone marrow infiltration in MRI at the time of diagnosis. However, even in stage I disease (Durie and Salmon) and negative X-ray films bone marrow infiltration in MRI may be detected in 29-50% of patients. Those patients typically show an earlier disease progression. Recently, MRI has been implemented in the clinical staging of patients with multiple myeloma. MRI may also monitor response to therapy. Signs of good response in cases with focal involvement are: reduction of signal intensity on T2-weighted spin echo images, lack or rim-like enhancement after contrast material injection or even a normalisation of bone marrow signal. In case of diffuse involvement a partly patchy reconversion to fatty marrow can be seen.     

CT measurement of coronary calcium mass: impact on global cardiac risk assessment

Coronary calcium mass percentiles can be derived from electron beam CT as well as from multidetector-row CT of all manufacturers. Coronary calcium mass may serve as a more individualized substitute for age for cardiac risk stratification. The aim was to investigate the potential impact of CT coronary calcium mass quantification on cardiac risk stratification using an adjusted Framingham score. Standardized coronary calcium mass was determined by multidetector-row CT in a total of 1,473 patients (1,038 male, 435 female). The impact on risk stratification of replacing the traditional Framingham age point score by a point score based on calcium mass relative to age was tested. Any coronary calcium found in males in the age group of 20–34 years and females in the age group of 20–59 years results in an increase of the Framingham score by 9 and 4–7 points, respectively. Only in males 65 years of age and older, none or minimal amounts of coronary calcium decrease the Framingham score by three points. The coronary calcium mass and age-related scoring system may have impact on the reassignment of patients with an intermediate Framingham risk to a lower or higher risk group.     

Cajal-like cells in the human upper urinary tract

PURPOSE: Interstitial cells of Cajal (ICCs) have an important role in the regulation of gut motility as they are responsible for the slow wave activity of smooth muscle. It is still unknown if ICCs also occur in the human upper urinary tract. Since these cells express and are marked by the c-kit receptor CD117, we investigated its occurrence and distribution along the human upper urinary tract. MATERIALS AND METHODS: Tissues from 56 human ureters, spanning proximal, middle and distal ureter segments, were analyzed by indirect immunohistochemistry using the alkaline phosphatase-anti-alkaline phosphatase method and double labeling immunofluorescence on consecutive tissue sections. Several monoclonal and polyclonal antibodies to c-kit receptor were used in combination with various cell markers for histiocytic, mast cell, endothelial, epithelial, neuronal, smooth muscle and stem cell differentiation. RESULTS: The c-kit receptor was found in 3 cell types of the ureter and in round or spindle-shaped cells. Due to their antigenic profile the first one was revealed as mast cells occurring in all layers of the ureteral wall except the urothelium. In contrast, the population of spindle-shaped cells was only marked by c-kit receptor, thus, resembling ICCs. These ICC-like cells were found among the inner and outer smooth muscle layers, and in the lamina propria. They showed a slight decrease from proximal to distal ureteral segments. However, unlike intestinal ICCs their cytomorphology differed and some cells, representing the third group of c-kit receptor positive cells, were found within the urothelium. CONCLUSIONS: Our data demonstrate the presence of ICC-like cells and their ubiquitous distribution in the human ureter. The physiological importance and pathological significance of these findings must be evaluated by functional studies and investigations of certain pathological with urinary outflow disturbance conditions.     

Genuine DNA/polyethylenimine (PEI) complexes improve transfection properties and cell survival

Polyethylenimine (PEI) has been described as one of the most efficient cationic polymers for in vitro gene delivery. Systemic delivery of PEI/DNA polyplexes leads to a lung-expression tropism. Selective in vivo gene transfer would require targeting and stealth particles. Here, we describe two strategies for chemically coupling polyethylene glycol (PEG) to PEI, to form protected ligand-bearing particles. Pre-grafted PEG-PEI polymers lost their DNA condensing property, hence their poor performances. Coupling PEG to pre-formed PEI/DNA particles led to the expected physical properties. However, low transfection efficacies raised the question of the fate of excess free polymer in solution. We have developed a straightforward a purification assay, which uses centrifugation-based ultrafiltration. Crude polyplexes were purified, with up to 60% of the initial PEI dose being removed. The resulting purified and unshielded PEI/DNA polyplexes are more efficient for transfection and less toxic to cells in culture than the crude ones. Moreover, the in vivo toxicity of the polyplexes was greatly reduced, without affecting their efficacy.     

Myokardperfusion in Ruhe und unter Belastung

AIM: Performance of combined rest/stress MR perfusion studies and the analysis of qualitative signal intensity parameters in comparison with 99mTc-SestaMIBI SPECT in patients with known coronary artery disease (CAD). METHODS: Sixteen patients with CAD underwent MR myocardial perfusion assessment at rest and after dipyridamole-induced hyperemia. Qualitative parameters (SI increase, SI upslope) of the SI time-curves were evaluated and characteristics of normal, reversible and persistent hypoperfused myocardium as assessed by 99mTc-SestaMIBI SPECT were compared. RESULTS: Compared with the rest values, normal myocardium showed a significant increase of the SI upslope during hyperemia (P < 0.001), whereas persistent (P = 0.07) and reversible (P = 0.15) hypo-perfusions showed only minor changes. SI increase over baseline also showed a significant increase only in normal myocardium (P < 0.001). At rest, reversible ischemic areas showed no significant differences from normal myocardium, whereas during hyperemia SI increase was significantly lower (P = 0.02). CONCLUSIONS: Qualitative SI parameters of a combined rest/stress MR myocardial perfusion study allow to differentiate normal from reversibly or persistently hypoperfused myocardium.     

Spatial behaviour is driven by proximal cues even in mildly impaired Parkinson's disease

This investigation addresses the question whether patients with mild to moderate Parkinson's disease (PD) show spatial deficits in real-life settings. Therefore, a "search through"-locomotor task incorporating basic features of both the radial arm maze and the Morris water maze paradigms was used. The participants had to find and remember five out of twenty hidden locations within a completely controlled environment. Different spatial memory errors and inter-response intervals were recorded automatically. Fourteen patients with idiopathic PD and fourteen healthy controls matched for age, sex, handedness, and education were investigated. Patients and controls were widely comparable with respect to intelligence, verbal memory, and executive functions. Results show that performance deteriorated in about half of the patients if the starting position was moved by 90 degrees and the proximal cues were deleted simultaneously. This deficit was systematically related to specific measures of attention. Moreover, patients were less able to update their locomotor strategies towards a more effective strategy. Results are discussed with respect to the patient's inability to generate rules which can be flexibly used in changing environments, especially if proximal cues are removed. It is concluded that deficits in spatial behaviour can be elicited even in near-to-real-life situations if appropriate testing procedures are used.     

Diffusion-weighted imaging of the spinal column

Diffusion-weighted imaging of the musculoskeletal system including the spine is a new MR imaging method. Several studies have shown significantly different diffusivities for various pathologic conditions such as edema and tumor. The specificity of diagnosis may be increased and therapeutic effects may be monitored. Diffusion-weighted sequences especially have been shown to be an additional tool for differentiating vertebral fractures caused by osteoporotic collapse with bone marrow edema and metastatic collapse. Inclusion criteria should include: (1) unknown reason for the vertebral collapse, (2) lack of sclerosis, and (3) no prior therapy. Patients with trauma or treated metastases may exhibit different signal intensities. In general, those patients do not pose problems in differential diagnosis. New sequence developments and higher magnetic field gradients should be able to increase spatial resolution and decrease problems from motion artifacts. Studies with larger patient groups and sequences that quantify the results with ADCs are the necessary next steps.