White matter brain lesions in midlife familial hypercholesterolemic patients at 3-Tesla magnetic resonance imaging.

BACKGROUND: Patients with hypercholesterolemia of 60 years and older have an increased risk for white matter brain lesions and dementia. PURPOSE: To investigate whether patients with familial hypercholesterolemia (FH) develop white matter lesions at 3-Tesla (T) MRI as early as in midlife. MATERIAL AND METHODS: Non-diabetic, nonsmoking, and non-hypertensive heterozygous FH patients on treatment with maximally tolerated dose of a statin for more than 5 years (n = 14) and matched controls (n = 22) aged 25 to 60 years of age were studied. Imaging was performed at 3T with a fluid-attenuated T2-weighted MR pulse sequence and a T1-weighted spin-echo pulse sequence following 10 ml of i.v. gadopentetate dimeglumine. Images were evaluated by two independent readers. Fasting blood samples were taken. Student's t test was employed at P<0.05. RESULTS: Three volunteers and one FH patient had white matter lesions (P<0.53). No other evidence of past ischemic stroke was observed. Mean total serum cholesterol and low-density lipoprotein (LDL) cholesterol were significantly higher in the FH group (6.0+/-1.1 vs. 5.1+/-0.9 mmol/l, P<0.02 and 4.1+/-0.9 vs. 3.1+/-0.8 mmol/l, P<0.004, respectively). CONCLUSION: Heterozygous FH patients on statin treatment in the age range of 25 to 60 years are not at increased risk of white matter lesions at 3T MRI.

A comparison of MR cholangiopancreatography at 1.5 and 3.0 Tesla.

Clinical MR systems operating at 3.0 Tesla have the potential to significantly improve spatial resolution due to the boost in intrinsic signal to noise ratio. However, body imaging at these field strengths presents a number of technical challenges. We performed a prospective pilot study in which 10 patients underwent an MR cholangiopancreatography (MRCP) examination consecutively on 1.5 and 3.0 Tesla systems (both Philips Intera). An axial half Fourier segmented turbo spin echo (HASTE) sequence and a coronal thick-slab 2D turbo-spin echo (TSE) sequence were compared on both systems. A reader measured the signal intensity (SI) ratios of common bile duct (CBD): liver, and CBD: fat on HASTE images and CBD: liver on the TSE images. A second reader performed a qualitative analysis of the intrahepatic and extrahepatic biliary anatomy. Quantitative data was compared using the paired t-test and qualitative data with the paired Wilcoxon signed rank test with p < 0.05. The quantitative analysis of the HASTE sequences showed a slightly higher signal intensity ratio (CBD:liver) at 3.0 Tesla compared with 1.5 Tesla (8.1 vs 5.6, p = 0.002). No significant difference was found between the SI ratios of (CBD:fat) on HASTE images or (CBD:liver) on TSE images. The qualitative analysis showed superior image quality of 3.0 Tesla over 1.5 Tesla images on both HASTE (31 vs 25, p = 0.032), and TSE sequences (34 vs 28, p = 0.043). This pilot study shows that MRCP is feasible at 3.0 Tesla with some improvement in image quality and signal characteristics. Further development may be achieved with sequence optimization and improved coil design.

[Characterization of an experimental venous thrombus model with MRI, phlebography and histology]. / Charakterisierung eines experimentellen venösen Thrombosemodells mittels MRT, Phlebographie und Histologie.

INTRODUCTION: Several magnetic resonance (MR) techniques designed to demonstrate the characteristic signal intensity of blood degeneration products of thrombi have been suggested, but the effect of thrombus organization on the MR display, in particular with regard to its temporal evolution, remains to be determined. It is the purpose of this study to develop a stagnation thrombus model in rabbits and to characterize thrombus at different ages with two (MR) imaging techniques, phlebography and histology. MATERIALS AND METHODS: Venous stagnation thrombi were induced in the external jugular veins of rabbits using a minimally invasive radiological technique to produce artificial embolic vascular occlusion and hypercoagulability. Twenty-five animals were divided into 5 groups of 5 animals, and each group underwent 1.5 T MR imaging at 1, 3, 5, 7 and 9 days after thrombus induction using a T1-weighted magnetization-prepared rapid gradient-echo sequence (MP-RAGE: TR 10.4 msec, TE 4.0 msec, FA 15 degrees ) and a T2-weighted fast low-angle shot sequence (FLASH: TR 54 msec, TE 18 msec, FA 15 degrees ). The thrombus length was measured on the T1-weighted images. Thrombus conspicuity, signal intensity, and heterogeneity on T2* weighted images were described using visual scales. Radiographic venography and histology served as reference methods. RESULTS: Thrombi were successfully induced in all animals. The overall thrombus length decreased from 43 +/- 9 (day 1 after induction) to 23 +/- 4 mm (day 9). On 3D-reconstructions of the T1-weighted images, the visible portion of the true thrombus length relative to the overall thrombus length was 0.16 +/- 0.3 (day 1), 0.24 +/- 0.3 (day 3), 0.38 +/- 0.5 (day 5), 0.06 +/- 0.1 (day 7) and 0.00 (day 9). Sixteen of 25 thrombi were detectable with the T2*-weighted technique. The overall thrombus signal intensity decreased with the age of the thrombus from day 1 to day 9. The histological evaluation showed that the rabbit thrombi closely resemble human thrombi morphologically. CONCLUSIONS: The thrombus model closely resembles the human venous stagnation thrombus of different organizational stages. With state-of-the-art MRI techniques, thrombi were only partially displayed with the visibility depending on thrombus age. The model may be suitable for evaluating new and potentially more effective MRI techniques for improved thrombus visualization.

Evaluation of gadobutrol in a rabbit model as a new lanthanide contrast agent for computed tomography.

RATIONALE AND OBJECTIVES: The efficacy of the neutral lanthanide contrast agent gadobutrol was compared to that of the iodinated contrast agent iopromide in rabbits. METHODS: The computed tomography (CT) attenuation of increasing concentrations of gadolinium (Gd) (gadobutrol) and iodine (I) (iopromide) was measured in Hounsfield units (HU) in aqueous solution at 80, 120, and 137 kV. The peak enhancement (net increase in CT attenuation compared with baseline) and the time-enhancement product in the aorta and in the renal parenchyma of the outer and inner cortex were measured in rabbits over a 5-minute period after the animals were given single intravenous injections of 0.7, 1.0, and 1.5 mmol Gd/kg of gadobutrol and 1.0 and 2.4 mmol I/kg of iopromide. RESULTS: In vitro, the CT attenuation of gadolinium was 40% higher than that of iodine at equivalent mass concentrations (120 kV). The mean peak enhancements in the aorta after the injections of 0.7, 1.0, and 1.5 mmol Gd/kg and 1.0 and 2.4 mmol I/kg were 216, 313, 591, 224, and 498 HU, respectively. In addition, a 30-second injection of the high dose of gadobutrol resulted in an attenuation profile that was suitable for a three-dimensional reconstruction of the aorta and the renal vasculature. CONCLUSIONS: Because of the higher CT attenuation of gadolinium compared with that of iodine, the neutral macrocyclic chelate gadobutrol is a more effective contrast agent than iopromide for CT at lower doses of the imaging atom.

Functional hepatobiliary imaging with gadolinium-EOB-DTPA. A comparison of magnetic resonance imaging and 153gadolinium-EOB-DTPA scintigraphy in rats.

RATIONALE AND OBJECTIVES: Gadolinium-EOB-DTPA (Gd-EOB-DTPA) is a hepatobiliary magnetic resonance (MR) imaging contrast medium designed to detect focal liver lesions. The objective of this study was to evaluate dynamic Gd-EOB-DTPA-enhanced MR imaging as a new method for assessing liver excretory function and to compare it with a scintigraphic method, the gold standard. METHODS: Changes in scintigraphic liver activity or MR liver signal intensity were intraindividually monitored over time after intravenous injection of 50 mumol Gd/kg of Gd-EOB-DTPA in controls and rats with common bile duct obstruction or L-ethionine-induced fatty liver (n = 6). RESULTS: A comparison of liver scintigraphy and MR imaging revealed that elimination half-lives of Gd-EOB-DTPA were significantly longer in rats with common bile duct obstruction (scintigraphy: 100 +/- 27 minutes; MR imaging: 59 +/- 18 minutes) or fatty liver (scintigraphy: 94 +/- 30 minutes; MR imaging: 72 +/- 32 minutes) than in controls (scintigraphy: 20 +/- 2 minutes; MR imaging: 18 +/- 3) (P < 0.05). CONCLUSIONS: Like liver scintigraphy, functional MR liver imaging using Gd-EOB-DTPA is feasible and can differentiate normal controls from models of biliary and hepatocyte disease.

Iron-oxide-enhanced magnetic resonance imaging of atherosclerotic plaques: postmortem analysis of accuracy, inter-observer agreement, and pitfalls.

INTRODUCTION: Contrast-enhanced magnetic resonance (MR) imaging using ultra small superparamagnetic iron oxide (USPIO) particles is a new noninvasive modality for imaging inflammatory atherosclerotic plaques. We determined the accuracy, interobserver agreement, and potential sources of error of this technique by means of postmortem MR imaging of aortic preparations. MATERIAL AND METHODS: Anesthetized atherosclerotic Watanabe heritable hyperlipidemic (WHHL) rabbits were studied after administration of different dosages of intravenous USPIO (DDM 43/34, IDF Berlin, Germany) and different postcontrast time intervals. A (n = 5) received 0 micromol Fe/kg. B (n = 5) received 50 micromol Fe/kg, 8-hour postcontrast interval. C (n = 5) received 50 micromol, 24 hours. D received 200 micromol, 48 hours. The aortas were removed and 3-mm segments prepared for postmortem examination by MR imaging using a T2-weighted gradient-echo sequence (TR/TE/FA; 41 milliseconds/11 milliseconds/15 degrees ), radiography (mammography), and histology (iron staining). USPIO accumulation was defined as the presence of 20 iron-positive cells per microscopic view (x100 magnification). Two independent readers analyzed the MR images and rated their confidence level for a positive MRI finding, defined as a focal signal loss, on a 5-point scale. The results were evaluated by receiver-operator characteristic (ROC) analysis. RESULTS: Of a total of 621 vessel segments technically acceptable for evaluation, 534 were histologically negative and 87 positive. Accuracy, expressed as the area under the ROC curve, was 0.85 for reader 1 and 0.88 for reader 2. Interobserver agreement was 0.67. False-positive findings were established by at least one reader for 121 of the 621 segments, false-negative findings for only 15 segments. Calcifications and mural thrombi were identified as potential sources of error of the method. CONCLUSION: Postmortem USPIO-enhanced MR imaging of atherosclerotic plaques showed a high accuracy and good interobserver agreement in the animal model used here. Further optimization of the method should aim at reducing the rather high percentage of false-positive results.

Neurogenic hypertension. A new MRI protocol for the evaluation of neurovascular compression of the cranial nerves IX and X root-entry zone.

OBJECTIVE: Neurovascular compression of the rostral ventrolateral medulla (RVLM) has been implicated in the pathogenesis of essential hypertension. Although MRI has been widely used to evaluate the morphologic relation of structures in this region, spatial resolution of the previously used techniques was limited. This article describes the use of a new MRI protocol that combines two sequences with improved spatial resolution and complementary image information as well as a set of defined criteria for image analysis. METHODS: MRI of the brain stem was performed in 60 hypertensive and 50 normotensive subjects using a 3D-CISS and a 3D-FISP-MRA sequence. Neurovascular contact in the RVLM was independently assessed by four readers using predefined criteria and compared with a consensus finding. Agreement was expressed by kappa statistics on a 0 to 1 scale. RESULTS: Left-sided neurovascular contact within the RVLM was found in 13 (22%) hypertensive and 6 (12%) control subjects. The inter-reader agreement for positive and negative findings ranged from 0.47 to 0.79; agreement to the consensus finding ranged from 0.65 to 0.90. CONCLUSIONS: The combination of 3D-CISS and arterial flow-sensitive 3D-FISP, together with the evaluation criteria defined in this study, can be used for describing the finer anatomic features of the brain stem, and in particular for investigation of neurovascular contact of the IX/X cranial nerve root-entry zone. The high quality of images and the substantial or almost perfect reader-consensus agreement should make this protocol useful for future investigations of the neurovascular compression syndrome in patients with essential hypertension and possibly in other neurovascular compression syndromes, such as trigeminal neuralgia and hemifacial spasm.

Superparamagnetic iron oxide-enhanced MRI of atherosclerotic plaques in Watanabe hereditable hyperlipidemic rabbits.

RATIONALE AND OBJECTIVES: Inflammatory atherosclerotic plaques are characterized by increased endothelial permeability and multiple macrophages. Blood-pool MRI contrast agents like superparamagnetic iron oxide (SPIO) have an affinity for the monocyte-macrophage system and thus, may label inflammatory plaques. The objective was to demonstrate SPIO uptake in plaques of atherosclerotic rabbits by MRI and histology. METHODS: Aortas of anesthetized Watanabe hereditable hyperlipidemic rabbits were studied with a moderately T2*-weighted gradient-echo sequence at 1.5 T. Four groups of five animals each were studied: (1) without ultrasmall SPIO (carboxydextran coating; particle size, 25 nm; estimated plasma half-life, 6 hours) or with imaging after intravenous injection of SPIO at a dose (micromol Fe/kg) and postcontrast time delay (hours) of 50/8 (2), 50/24 (3), or 200/48 (4). In vivo MRI was compared with corresponding ex vivo histological iron stains. RESULTS: Animals receiving 200 micromol Fe/kg demonstrated areas of focal signal loss clearly confined to the aortic wall on a mean of 24 +/- 9 (31% +/- 11%) of 76 +/- 5 images compared with 0 +/- 0 of 76 +/- 5 images in controls (P = 0.009). The number of images with this finding in groups 2 and 3 was not significantly different compared with controls. By microscopy, SPIO-iron was seen in the endothelial cells and subendothelial intimal macrophages of atherosclerosis-prone aortic wall segments. Atherosclerotic lesions demonstrating iron uptake also showed a high macrophage content. CONCLUSIONS: SPIO accumulates in aortic plaques of atherosclerotic rabbits, producing a characteristic MRI finding. As SPIO accumulates in plaques with increased endothelial permeability and a high macrophage content, two established features of plaque inflammation, it may have a potential for noninvasive assessment of inflammatory atherosclerotic plaques.

Thyrotropin-releasing hormone and amphetamine produce different patterns of behavioral excitation in rats.

We compared the arousal and hyperactivity produced by intraperitoneal (i.p.) injections of thyrotropin-releasing hormone (TRH, pGlu-His-Pri-NH2; 10, 20, 30 and 60 mg/kg) and 0.3 and 2 mg/kg d-amphetamine (low and moderate amph., respectively) by measuring the occurrence of discrete behavioral items with a behavioral sampling and scoring method. To minimize extraneous variables affecting activity, rats were caged singly inside isolated observation chambers and tested in the daytime after a 2.5 h period of habituation. Under these conditions, vehicle (0.9% NaCl)-treated rats were inactive and either rested or slept through 80% of all time samples taken in the hour after injection. Both TRH and amph. produced significant arousal from sleeping, but TRH, at all doses tested, produced less arousal than moderate amph. and a pattern of behavioral responses which differed from both low and moderate amph. Moderate amph. produced marked increase in forward locomotion and rearing, but low amph. and TRH did not. Both TRH and low amph. increased grooming (perhaps simply by increasing wakefulness), but TRH failed to increase sniffing, a cardinal feature of ampha.-induced excitement. Unlike amph., TRH produced wet-dog shakes, piloerection, tail elevation and teeth chattering. Both mod. amph. and TRH significantly produced increased activity when compared to controls as assessed with photocell counts, though the amph. effect was more robust. The lack of arousal after i.p. injections of thyroid-stimulating hormone (10 I.U./kg) or melanocyte-stimulating hormone release-inhibiting factor (Pro-Leu-Gly-NH2; 60 mg/kg) is evidence that TRH-induced arousal is neither mediated by activation of the pituitary-thyroid axis nor by a non-specific effect of tripeptides generally.

N-Alkylated derivatives of 5-fluorouracil.

Some N-alkyl derivatives of 5-fluorouracil were designed to act as latent depot forms of 5-fluorouracil. A general and efficient method for the syntheses of the alkylated derivatives is described. As expected, the alkylated derivatives of 5-fluorouracil did not show any cytotoxicity in cell culture systems even up to 10(-4) M concentration. The synthesis of 1,3-dimethyl-5-fluoro-5,6-dihydrouracil is also described.

[Iron-oxide-enhanced MR imaging of inflammatory atherosclerotic lesions: overview of experimental and initial clinical results]. / Eisenoxidverstärkte MRT inflammatorischeratherosklerotischer Läsionen: Ubersichtexperimenteller und erster klinischer Ergebnisse.

Numerous pathologic studies in the 1990's have shown atherosclerosis to be a chronic inflammatory disorder. This new insight and the advent of new plaque-stabilizing drugs, in particular antilipemic agents (statins), have led to an increased clinical interest in the development of new imaging modalities. These are aimed at visualizing the inflammatory atherosclerotic wall lesion as reflecting the active progression of the disease process and at identifying so-called vulnerable or high-risk lesions that are associated with a higher rate of vascular complications. A diagnostic modality currently undergoing investigation in terms of its potential for the diagnostic assessment of atherosclerosis is contrast-enhanced magnetic resonance imaging (MRI) using certain blood pool contrast media such as ultrasmall superparamagnetic iron oxide (USPIO) particles. Endothelial dysfunction and macrophage infiltration are two crucial pathomechanisms of atherosclerosis and these mechanisms also underlie the accumulation of iron oxide particles in experimental and human atherosclerotic lesions. Experimental results furthermore suggest that there is selective uptake of iron oxide by thrombi. The following experimental MR imaging techniques have a potential for providing complementary diagnostic information in assessing atherosclerotic lesions: 1. Unenhanced MRI for visualizing vulnerable plaques (wall thickness, fibrous cap, lipid core). 2. Visualization of the vessel lumen and quantitative assessment of stenosis using iron-oxide-enhanced MR angiography. 3. Delayed MRI studies for the functional characterization of inflammatory lesions (T 2 -effects produced by iron oxide uptake in macrophages of inflammatory lesions) with a potential for identifying mural thrombus as a sign of plaque rupture (T 1 -effects produced by binding of iron oxide to the thrombus). This article presents the experimental and initial clinical results obtained with iron-oxide-enhanced MRI of atherosclerotic lesions.

[Superparamagnetic iron oxide enhanced MR angiography of the portal vein system]. / SPIO-unterstützte MR-Angiographie des portalvenösen Systems.

PURPOSE: Superparamagnetic iron oxide (SPIO) is used for the detection of focal liver lesions. The current study examines whether the blood-pool effect of an approved substance is adequate for contrast-enhanced MR angiography of the portal venous system. METHODS AND MATERIALS: Fifteen patients [9 women, 6 men, mean age 57 (34-73)] were examined with a breathhold 3D-FISP sequence (TR/TE/FA; 5 ms/2 ms/25 degrees) at 1.5 Tesla (Vision; Siemens, Erlangen) during the last third of a half-hour Infusion of a standard dose (15 mumol Fe/kg) of AMI-25 (Endorem, Guerbet Co., France). The image quality of source images and 3D reconstructions was evaluated by two examiners using a 3-point scale. RESULTS: Large vessels (portal vein, left and right branch of the portal vein, superior mesenteric vein, splenic vein) are visualized well or adequately in 80-93% of the cases, while this was achieved in only 53-60% of the small veins (vessels of the first order emptying into the superior mesenteric vein and the spleen). Venous arcades of the mesenterium are not visible by this technique. CONCLUSION: SPIO-supported MRA of the portal venous system yields usable results in the majority of patients. A possible indication is preinterventional angiography together with an SPIO examination for the detection of focal liver lesions.

[SPIO-enhanced MR angiography for the detection of venous thrombi in an animal model]. / SPIO-unterstützte MR-Angiographie zur Detektion venöser Thromben im Tiermodell.

PURPOSE: An animal model is used to investigate whether MR angiography combined with super-paramagnetic particles of iron oxide (SPIO) is suitable for detecting thromboses. METHODS: 42 rats in groups of 7 each were examined on days 1, 3, 5, 7, 9 and 11, respectively, after mechanical/chemical thrombus induction in a 1.5 Tesla magnet with a FISP sequence (TR/TE/FA 50 ms/6 ms/40 degrees). Imaging was performed before and up to 90 minutes after intravenous injection of 30 mumol FE/kg BW of the experimental SPIO (hydrodynamic diameter, 34 +/- 17 nm LLS; R1 and R2 relaxivity at 0.47 T, 31 and 57 L/(mmol*s)). MIP reconstructions of MR angiographies were submitted to consensus assessment by two examiners. using histology as the gold standard. RESULTS: The image quality of MIP reconstructions was rated as good in 38 of 42 cases. With regard to thrombotic vessel occlusion, MR angiography coincided with histology in 17 of 42 cases and differed in 25, lumen narrowing being overestimated by MRI in 4 cases and underestimated in 21. In these 21 cases, the histologically observed recanalization could not be detected by MR angiography. CONCLUSIONS: SPIO-enhanced MR angiography achieves adequate vessel contrast and reliable thrombus detection in animal experiments. Partial volume effects prevent microscopically observed recanalization from being detected by clinical MRI.

Establishing a clinical cardiac MRI service.

After several years of research development cardiovascular MRI has evolved into a widely accepted clinical tool. It offers important diagnostic and prognostic information for a variety of clinical indications, which include ischaemic heart disease, cardiomyopathies, valvular dysfunction and congenital heart disorders. It is a safe non-invasive technique that employs a variety of imaging sequences optimized for temporal or spatial resolution, tissue-specific contrast, flow quantification or angiography. Cardiac MRI offers specific advantages over conventional imaging techniques for a significant number of patients. The demand for cardiac MRI studies from cardiothoracic surgeons, cardiologists and other referrers is likely to continue to rise with pressure for more widespread local service provision. Setting up a cardiac MRI service requires careful consideration regarding funding issues and how it will be integrated with existing service provision. The purchase of cardiac phased array coils, monitoring equipment and software upgrades must also be considered, as well as the training needs of those involved. The choice of appropriate imaging protocols will be guided by operator experience, clinical indication and equipment capability, and is likely to evolve as the service develops. Post-processing and offline analysis form a significant part of the time taken to report studies and an efficient method of providing quantitative reports is an important requirement. Collaboration between radiologists and cardiologists is needed to develop a successful service and multi-disciplinary meetings are key component of this. This review will explore these issues from our perspective of a new clinical cardiac MRI service operating over its first year in a teaching hospital imaging department.

Computed tomography of the human pineal gland for study of the sleep-wake rhythm: reproducibility of a semi-quantitative approach.

PURPOSE: To propose a semi-quantitative computed tomography (CT) protocol for determining uncalcified pineal tissue (UCPT), and to evaluate its reproducibility in modification of studies showing that the degree of calcification is a potential marker of deficient melatonin production and may prove an instability marker of circadian rhythm. MATERIAL AND METHODS: Twenty-two pineal gland autopsy specimens were scanned in a skull phantom with different slice thickness twice and the uncalcified tissue visually assessed using a four-point scale. The maximum gland density was measured and its inverse graded on a non-linear four-point scale. The sum of both scores was multiplied by the gland volume to yield the UCPT. The within-subject variance of UCPT was determined and compared between scans of different slice thickness. RESULTS: The UCPT of the first measurement, in arbitrary units, was 39+/-52.5 for 1 mm slice thickness, 44+/-51.1 for 2 mm, 45+/-34.8 for 4 mm, and 84+/-58.0 for 8 mm. Significant differences of within-subject variance of UCPT were found between 1 and 4 mm, 1 and 8 mm, and 2 and 8 mm slice thicknesses (P<0.05). CONCLUSION: A superior reproducibility of the semi-quantitative CT determination of UCPT was found using 1 and 2 mm slice thicknesses. These data support the use of thin slices of 1 and 2 mm. The benefit in reproducibility from thin slices has to be carefully weighted against their considerably higher radiation exposure.

Quantitative assessment of iron-oxide-enhanced magnetic resonance imaging of the liver: Vessel isointensity is a potential characteristic of liver hemangiomas on late T1-weighted images.

PURPOSE: To test whether a new quantitative measure, the tumor-to-vessel ratio, obtained from late post-iron-oxide-enhanced T1-weighted images allows for differentiating hemangiomas from liver metastases or all malignant liver lesions. MATERIAL AND METHODS: Twenty-six patients (mean 57, range 33-79 years) were prospectively studied at 1.5T magnetic resonance imaging (MRI) with a T1-weighted 2D fast low-angle shot (FLASH) sequence (repetition time/echo time/flip angle; 200 ms/4.8 ms/90 degrees ) and a T2-weighted turbo spin-echo sequence (4072 ms/99 ms/180 degrees ). Imaging was carried out before and at intervals up to 18 min after IV injection of Ferucarbotran (Resovist, Schering, Germany). In 19 patients, one representative malignant lesion was analysed. Eleven hemangiomas were evaluated in 7 patients. Two readers performed a consensus reading with a signal intensity measurement in a lesion, normal liver and hepatic veins, from which ratios were computed. RESULTS: On T1-weighted iron-oxide-enhanced MRI of 30 lesions, tumor-to-vessel signal intensity ratios were distinct in hemangiomas (median 1.04, range 0.99-1.10) as opposed to either metastases (0.64, 0.33-0.77; P < 0.05) or all malignant lesions taken together (0.64, 0.33-0.98; P < 0.05), while the tumor-to-liver ratio was not. CONCLUSION: The tumor-to-vessel ratio may help to differentiate between hemangiomas and metastases. A ratio greater than 0.98 allowed differentiating hemangiomas from metastases with a wide safety margin.

Technical report: Magnetic resonance direct thrombus imaging at 3 T field strength in patients with lower limb deep vein thrombosis: a feasibility study.

AIM: To investigate the feasibility of imaging lower limb deep vein thrombosis using magnetic resonance imaging (MRI) at 3.0 T magnetic field strength with an optimized a T1 magnetization prepared rapid gradient echo technique (MP-RAGE) in patients with normal volunteers as controls. MATERIALS AND METHODS: Patients with deep vein thrombosis (n = 4), thrombophlebitis (n = 2) and healthy volunteers (n = 9) were studied. MRI of the distal thigh and upper calf was performed at 3.0 T with MP-RAGE using two pre-pulses to suppress blood and fat (flip angle 15 degrees, echo time 5 ms, and repetition time 10 ms). A qualitative analysis was performed for detection of thrombi and image quality. Contrast-to-noise ratios were determined in thrombosed and patent veins. RESULTS: Thrombi were clearly visible as high-signal intensity structures with good suppression of the anatomical background. A blinded reader accurately diagnosed 15 out of 16 cases. The contrast-to-noise ratio measurements showed a positive contrast of thrombus over background muscle 16.9 (SD 4.3, 95% CI: 12.5-21.3) and a negative contrast of the lumen to muscle in patent veins of normal volunteers -7.8 (SD 4.3, 95% CI: -11.1 to -4.5), with p = 0.0015. CONCLUSION: Thrombi generate high signal intensity at 3.0 T allowing for their direct visualization if flowing blood, stationary blood and fat are sufficiently suppressed. This preliminary data supports the development of these techniques for other vascular applications.

MR angiography with superparamagnetic iron oxide: feasibility study.

Magnetic resonance (MR) angiography with blood-pool superparamagnetic iron oxide (SPIO) particles was evaluated in the whole-body vascular system. In 12 adult patients, three-dimensional fast imaging with steady-state precession was performed in successive steps from the lungs to the calves before and after a standard dose for liver imaging (15 mumol of iron per kilogram of body weight) of AMI-25. On SPIO-enhanced MR angiograms, visualization of the pulmonary arterial, whole-body, and lower extremity venous systems was graded as good or sufficient in all patients, and femoral vein thrombosis was clearly demonstrated in one patient.

Magnetic resonance imaging of the normal and diseased feline middle ear.

The magnetic resonance imaging appearance of the feline middle ear is described in three healthy cats and in five cats with middle ear disease. Owing to the good spatial resolution, multiplanar slice orientation as well as display high contrast resolution of soft tissue, in particular fluids, MR imaging was helpful prior to surgery. It is superior to radiography which failed to allow identification of the abnormality in two of our five cats. MR imaging for middle ear disease should include dorsal and transverse plane images using T1- and T2-weighted sequences. In the presence of a mass within the bulla or the external ear canal application of contrast medium is helpful.

Lipomatous hypertrophy of the interatrial septum: a commonly misdiagnosed mass often leading to unnecessary cardiac surgery.

Lipomatous hypertrophy of the interatrial septum is a benign cardiac mass that should be considered as part of the differential diagnosis for any atrial cardiac tumour. In the reported case, this lesion was initially suspected to be malignant and the patient was thus referred directly to cardiac surgeons for surgical removal. Unnecessary surgical intervention was swiftly averted because the cardiac surgeon promptly referred the patient for an expert echocardiogram that confirmed the diagnosis of lipomatous hypertrophy. The authors discuss the characteristic features of this lesion and how the diagnosis may be made based on several non-invasive imaging modalities without the need for a tissue biopsy. This condition is more common than initially thought and remains under-recognised by most clinicians. In such cases an increased awareness of this lesion along with the opinion of a specialist echocardiologist would help to avoid a misdiagnosis and unnecessary intervention.