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P Leander

Publications and source records attributed to P Leander.

At least 19 recordsLinked to original sources
PubMed2004

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC): intra- and interobserver variability in standardized drawing of regions of interest.

PURPOSE: To establish the reproducibility of a standardized region of interest (ROI) drawing procedure in delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC). MATERIAL AND METHODS: A large ROI in lateral and medial femoral weight-bearing cartilage was drawn in images of 12 healthy male volunteers by 6 investigators with different skills in MRI. The procedure was done twice, with a 1-week interval. Calculated T1-values were evaluated for intra- and interobserver variability. RESULTS: The mean interobserver variability for both compartments ranged between 1.3% and 2.3% for the 6 different investigators without correlation to their experience in MRI. Post-contrast intra-observer variability was low in both the lateral and the medial femoral cartilage, 2.6% and 1.5%, respectively. The larger variability in lateral than in medial cartilage was related to slightly longer and thinner ROIs. CONCLUSION: Intra-observer variability and interobserver variability are both low when a large standardized ROI is used in dGEMRIC. The experience of the investigator does not affect the variability, which further supports a clinical applicability of the method.

Adult↗
PubMed2003

Peripheral arterial disease. Contrast-enhanced 3D MR angiography of the lower leg and foot compared with conventional angiography.

PURPOSE: To determine whether contrast-enhanced 3D MR angiography (CE MRA) could replace digital subtraction angiography (DSA) for the evaluation of atherosclerotic peripheral vascular disease of the lower leg and foot. MATERIAL AND METHODS: Thirty-five patients with symptoms of atherosclerotic disease of the leg were examined prospectively with CE MRA of the foot and the lower legs as well as with DSA from the aorta to the pedal arches. The MRA technique was focused on optimal imaging of the arteries of the foot. RESULTS: The agreement between CE MRA and DSA for grading of stenosis was moderate to good (weighted kappa-values 0.48-0.80). The sensitivity of CE MRA for detection of significant stenosis (> or = 50%) was 92% and the specificity was 64% with DSA as gold standard. CONCLUSION: CE MRA is a fairly accurate method for the demonstration of atherosclerotic disease below the knee including the pedal arches. It can replace DSA for the assessment of distal arteries in patients with impaired renal function. However, image quality and resolution still needs to be improved before CE MRA can become the method of choice in all patients.

Aged↗
PubMed2002

MR and ultrasound in screening of patients with suspected biliary tract disease.

PURPOSE: The diagnostic value and cost-efficiency of MR imaging were compared with US before endoscopic retrograde cholangiopancreatography (ERCP) in patients with clinically suspected biliary tract disease. MATERIAL AND METHODS: In a prospective study of 219 patients, 85 were examined with both MR and US before ERCP. RESULTS: To find the correct diagnosis in the jaundiced patients the sensitivity of US, MR and ERCP was 53%, 93%, and 89%, respectively. In the patients with abdominal upper quadrant pain and normal serum bilirubin, the sensitivity of US, MR and ERCP was 50%, 100% and 70%, respectively. Examination with MR costs four times more than US. Screening with US and supplemental MR in non-diagnostic cases would cost 80% of the total amount compared to screening with MR only. CONCLUSION: MR had a higher sensitivity than US for diagnosing biliary tract disease and MR was superior to US in visualising stones in the common bile duct and in diagnosing the cause of cholestasis. However, screening with US and supplemental MR in non-diagnostic cases is at present most cost-effective. With increased accessibility and slightly lower costs, MR will probably replace US as screening method in patients with suspected biliary tract disease.

Adult↗
PubMed2002

MR characteristics of acute cholangitis.

PURPOSE: To describe the MR appearance of acute cholangitis and discuss the role of MR imaging as a diagnostic method in this disease. MATERIAL AND METHODS: Of 60 patients with clinical acute cholangitis, 12 were examined with MR before endoscopic retrograde pancreatography (ERCP). A retrospective review was performed of MR and ERCP findings. The MR findings registered were presence of biliary duct dilatation, intraluminal filling defects due to stones or sludge, bands of mucosal oedema of the biliary ducts, intra- and retroperitoneal oedema/fluid, and definition of the cause of obstruction, e.g. stones, stenosis or tumour was made. RESULTS: Acute cholangitis was related to obstruction from choledocholithiasis (n=8), pancreatic cancer (n=1), benign biliary duct stricture (n=1), papillary stenosis (n=1) and without evidence of an obstructing cause (n=1). One patient had an acute obstructive suppurative (toxic) cholangitis. CONCLUSION: MR imaging has a role in the non-invasive radiographic arsenal of techniques to confirm or exclude the diagnosis of acute cholangitis, especially in older patients where the clinical symptoms may be vague.

Acute Disease↗
PubMed2002

On the appearance of bile in clinical MR cholangiopancreatography.

PURPOSE: To study the appearance of bile in clinical MR cholangiopancreatography (MRCP) with special reference to its chemical and physical properties. MATERIAL AND METHODS: Gallbladder bile was collected during surgery from 38 patients and studied with respect to chemical constituents. The relaxation rates 1/T1 and 1/T2 of bile were also determined in vitro. In 16 of these 38 patients, abdominal imaging was performed using MRCP as well as T1-weighted GE sequences. RESULTS: For 9 of the 13 chemical parameters studied, a positive significant correlation with 1/T1 as well as 1/T2 was found. The median relaxation rates 1/T1 and 1/T2 were 0.76 and 1.48 s-1, respectively. The corresponding ranges were 0.38-3.13 s-1 and 0.70-5.75 s-1, respectively. On the MRCP images a few patients showed gallbladder of poor visibility due to low signal-to-noise ratio. This coincided with a high relaxation rate 1/T2 of bile. On the T1-weighted GE sequences a few patients showed hyperintense gallbladder relative to liver, coinciding with high relaxation rates 1/T1 of bile. CONCLUSION: Bile was found to show a large interindividual variation with respect to relaxation rates 1/T1 and 1/T2. The relaxation rates increased with increasing amounts of substances in the bile. For some patients (11%) MRCP imaging is unsuccessful due to high relaxation rate of bile.

Bile↗
PubMed2001

Gd-DTPA2)-enhanced MRI of femoral knee cartilage: a dose-response study in healthy volunteers.

The negatively charged contrast agent Gd-DTPA2- distributes inversely to the cartilage fixed charged density. This enables structural cartilage examinations by contrast-enhanced MRI. In line with the development of a clinically applicable protocol for such examinations, this study describes the temporal pattern of Gd-DTPA2- distribution in femoral knee cartilage at three different doses in healthy volunteers. Nineteen volunteers (ages 21-28 years) were examined with a 1.5T MRI system. Quantitative relaxation rate measurements were made in weight-bearing central parts of femoral cartilage using sets of five turbo inversion recovery images with different inversion times. The cartilage was analyzed before and four times (1-4 h) after an intravenous injection of Gd-DTPA2- at single, double, and triple doses: 0.1, 0.2, and 0.3 mmol/kg body weight, respectively. The increase in R1 postcontrast was linearly dose-related at all times. The highest R1 values were registered at 2 and 3 h postcontrast, suggesting 2 h to be optimal in the clinical situation. The triple dose indicated a subtle compartmental difference in men, with higher contrast distribution medially than laterally. Results suggest that the triple dose is needed to detect minor cartilage matrix differences.

Adult↗
PubMed2001

Radiology of the spleen.

The spleen is generally not considered a challenge to the radiologist. Most often it poses a problem by anomalies or an irregular but normal contrast enhancement; however, a variety of inflammatory, infectious and neoplastic diseases may involve the spleen. CT and ultrasonography are screening modalities for the spleen. For problem solving, MR imaging can be helpful, especially due to its free choice of the imaging plane and because of the high resolution in contrast MR imaging. Splenic angiography as a diagnostic tool has generally been replaced by CT, ultrasound, or MR and is now used as an interventional method, e. g., in non-surgical management of patients with chronic idiopathic thrombocytopenia or in patients with splenic trauma. This article reviews the radiology of the spleen, including anatomy, embryology, splenomegaly, splenic injury, infarction, cysts, tumors, abscesses, sarcoidosis, and AIDS. Knowledge about the use of different imaging modalities and underlying gross and microscopic pathologic features leads to a better understanding of the radiologic findings.

Diagnosis, Differential↗
PubMed2001

A new liposomal liver-specific contrast agent for CT: first human phase-I clinical trial assessing efficacy and safety.

In this first clinical trial liposome-encapsulated iodixanol, CT particles (CTP) were studied. The aims of the present trial were to assess the efficacy of CTP in CT and to determine the safety of different doses of CTP. A total of 47 healthy volunteers were enrolled in the present study. The CTP was administered at doses 10, 30, 70 and 100 mg encapsulated I/kg bw. Efficacy was assessed using single-slice CT of the abdomen and evaluated by dose-response attenuation curves over time in liver, spleen, and abdominal vessels. Safety was assessed by blood tests, clinical examinations and recording of subjective adverse events (AE). The attenuations in liver tissue increased with the dose and maximal values above baseline were 20, 39 and 45 HU at the doses 30, 70 and 100 mg encapsulated I/kg bw, respectively. Maximal increases were seen 12.5 min after contrast administration. As for liver, the attenuations in spleen increased with the dose, but higher attenuations were obtained. In early images clinically significant enhancement was seen in abdominal vessels. Mild and moderate subjective AE were encountered at the doses 70 and 100 mg encapsulated I/kg bw. The CTP is efficacious in enhancing hepatic and splenic tissues and in early imaging of abdominal vessels. Adverse event precludes a clinical use of CTP in the current formulation.

Adult↗
PubMed2001

MR imaging of upper abdomen following cholecystectomy. Normal and abnormal findings.

PURPOSE: To describe the normal MR appearance after cholecystectomy and the findings in patients with postoperative complications using fast pulse sequences in abdominal MR imaging. MATERIAL AND METHODS: In a prospective study of 119 patients, 64 were examined with MR after cholecystectomy. In total, 56 patients with uncomplicated cholecystectomy were examined with MR 1--5 days (mean 1.6 days) after cholecystectomy. Nine patients had an abdominal postoperative complication and 8 of these were examined with MR after the complication commenced 1--12 days after the cholecystectomy. RESULTS: Oedema in the gallbladder fossa was the only finding in 39 patients (61%), all with uneventful recovery. Small fluid collections in an area consistent with the gallbladder fossa were seen in 9/64 (14%) patients, of which 3 had surgical complications: 1 bleeding and 2 bile duct leakage. Twenty-two (34%) patients had small locally situated fluid collections adjacent to the liver, 14 were uneventful and 8 showed postoperative surgical complications. Seven patients had fluid in the rest of the abdomen of which 5 had surgical complications; 4 due to bile duct leakage and 1 acute pancreatitis. One patient had a postoperative bleeding not seen on MR images. CONCLUSION: MR is very sensitive in detecting fluid collections. Early MR findings following cholecystectomy are normally only subtle changes, mainly in the gallbladder fossa. Fluid collections diagnosed elsewhere than in the gallbladder fossa usually indicate a surgical complication and a surgical complication is unlikely if MR fails to show a fluid collection.

Abdomen↗
PubMed2000

MR imaging following herniography in patients with unclear groin pain.

The aims of the present study were to assess if MRI gives the same diagnostic information as herniography concerning the presence of hernias and reveals other causes of groin pain. The prospective study enrolled 20 patients referred for herniography, 6 women and 14 men, mean age 48 years. After herniography the patients underwent MRI using T1-weighted, fat-suppressed inversion recovery (STIR), and magnetic resonance cholangiopancreaticography (MRCP) pulse sequences. No contrast medium was administered at MRI. Herniography revealed 11 hernias and MRI depicted 8 of these. Magnetic resonance imaging depicted well the anatomy in the groins. In 3 patients where hernias were not revealed, MRI revealed inflammatory changes in the symphysis region as a possible cause of groin pain. The primary diagnostic tool for diagnosing hernias is herniography. If the herniogram is normal, MRI may reveal other causes of groin pain and may also better visualize related structures in the groin.

Female↗
PubMed2000

CT and MR imaging of the liver. Clinical importance of nutritional status.

PURPOSE: In an experimental study in rats a correlation between nutritional status and hepatic attenuation in CT and signal intensities in MR imaging was shown. Is physiological nutritional status of importance in clinical CT and MR imaging? MATERIAL AND METHODS: In a cross-over study including 12 healthy volunteers (6 women and 6 men, mean age 34 years), CT and MR imaging of the liver were performed with nutritional status at three different levels, i.e., normal, fasting and after glycogen-rich meals. CT and MR were performed on clinical imaging systems and hepatic attenuation and signal intensity, respectively, were assessed. In MR, T1-weighted, proton density-weighted and T2-weighted pulse-sequences were used. RESULTS: In CT there were significantly (p<0.01) higher liver attenuations in normal nutritional status and after glycogen rich-meals compared to the fasting condition. The difference between fasting and glycogen-rich meals were 10.5 HU for men, 7.4 for women and mean 8.8 HU for all 12 volunteers. In MR imaging the differences were small and non-significant. The results of this study are in accordance with an earlier experimental study in rats. CONCLUSION: In CT it may be of importance not to have patients in a fasting condition as it lowers the attenuation in normal liver tissue. The findings are important for planning of clinical studies where hepatic attenuation will be assessed and may be of some importance in clinical CT. In MR imaging the results indicate that the nutritional status is of less importance.

Animals↗
PubMed2000

MR imaging in clinically suspected acute cholecystitis. A comparison with ultrasonography.

PURPOSE: The diagnostic value of fast pulse sequences in MR imaging was compared with US in patients with clinically suspected acute cholecystitis. MATERIAL AND METHODS: In a prospective study of 94 patients, 35 were examined with both MR and US within 24 h. RESULTS: MR diagnoses were acute cholecystitis in 23, gallbladder and common bile duct stones in 3, other pathologic conditions of the abdomen in 7 and normal in 2 patients. US diagnoses were acute cholecystitis in 17, gallbladder stones in 8, other pathologic conditions of the abdomen in 2, normal in 5 and non-conclusive in 3 patients. CONCLUSION: MR has a higher sensitivity than US for diagnosing acute cholecystitis and, with increased accessibility, may be the first imaging method.

Acute Disease↗
PubMed2000

Glycogen content in rat liver. Importance for CT and MR imaging.

PURPOSE: CT and MR imaging are appropriate modalities for imaging of the liver. Contrast media are used to obtain a greater difference in attenuation and signal intensity, respectively, between normal liver tissue and focal lesions. However, no studies have attempted to determine whether physiological nutritional status of the liver during fasting is of importance for the native signal of normal liver tissue. MATERIAL AND METHODS: Using normal and fasting rats, we performed hepatic CT and MR imaging and glycogen analyses from excised tissue. RESULTS: A significantly higher liver attenuation in normal rats compared to fasting rats was found in CT. In MR images, there was a small but significantly lower liver signal-to-noise ratio in normal rats compared to fasting rats in T1-weighted and proton density-weighted images. Glycogen analyses showed depleted glycogen deposits in fasting rats and a mean glycogen content of 50.1 mg glucose equivalent/g liver tissue in normal rats. CONCLUSION: In CT, a normal nutritional status increases the native attenuation in normal liver tissue. The changes in attenuation in normal liver tissue correlate well with the additional attenuation of glycogen storage in the hepatocyte. The results indicate that the nutritional status is of less importance in MR imaging.

Animals↗
PubMed1999

Image artifacts due to a time-varying contrast medium concentration in 3D contrast-enhanced MRA.

The purpose of this work was to study image effects due to time-varying contrast medium concentration in contrast-enhanced three dimensional (3D) magnetic resonance angiography (MRA) images. Two different simulation models (1D and 3D) and two different contrast medium variation schemes were used. Phantom measurements were also performed. Experiments were performed for several different bolus timings. Similar sequence and image object parameters were used in both simulations and measurements (TE/TR 2. 1/7.8 mses, flip angle 30 degrees, T1/T2 1200-80/150-40 msec, flow velocity 100 cm/sec). A small variation in bolus timing yielded large variations in the appearance of the image effects, especially if the center of k-space was sampled in the vicinity of rapid contrast medium concentration variation. For a typical bolus injection in a patient, a severe signal loss but only minor ringing and edge artifacts appeared if the bolus injection was poorly timed. Effects of pulsatile flow were minor. The 3D model proved to be a useful tool in these studies. J. Magn. Reson. Imaging 1999;10:919-928.

Aorta↗
PubMed1998

Neuronal projections from the mesencephalic raphe nuclear complex to the suprachiasmatic nucleus and the deep pineal gland of the golden hamster (Mesocricetus auratus).

Neuronal projections from the mesencephalic raphe system to the suprachiasmatic nucleus and the pineal complex were mapped in this study of the golden hamster, by use of the anterograde tracer Phaseolus vulgaris-leucoagglutinin and the retrograde tracer cholera toxin subunit B. From the median raphe nucleus, a rostral projection ascended in the ventral part of the mesencephalon to continue in the medial forebrain bundle of the forebrain. Nerve fibres from this bundle innervated the ventral and medial parts of the suprachiasmatic nucleus. At the level of the interpeduncular nucleus of the mesencephalon, fibres of the ventral bundle bent dorsally to reach the epithalamic area and to continue in the forebrain in a periventricular position. Some of these fibres innervated the dorsal tip of the suprachiasmatic nucleus. The dorsal raphe nucleus was the origin of a nerve fibre bundle, located in the periaqueductal gray of the mesencephalon, innervating the deep pineal gland and pineal stalk. Injection of cholera toxin B into the suprachiasmatic nucleus labelled cells in the median raphe. Combination of the retrograde tracing from the suprachiasmatic nucleus and serotonin transmitter immunohistochemistry showed that some of the cholera toxin B-immunoreactive nerve cells also contained serotonin. Thus, this study of the golden hamster shows a serotonergic projection from the median raphe nucleus to the suprachiasmatic nucleus and a projection from the dorsal raphe nucleus to the deep pineal gland supporting physiological indications of an influence of serotonin on the photoreceptive circadian system of the brain.

Animals↗
PubMed1997

[Who dies of morphine and dextropropoxyphene intoxication? Danish experiences from the period 1979-1992].

We studied deaths following intoxication with dextropropoxyphene (D) and opioids (M) in Denmark 1979-1992 with special reference to the sex, age group, contributory cause of death (secondary diagnosis) and manner of death. Deaths following D increased until 1985 for both sexes, where a total of 46 women and 64 men died. In 1985 the National Board of Health drew public attention to this problem which led to a decrease in these deaths among men, while in women a paradoxical increase in suicides outnumbered a reduction in deaths from intoxication accidents. In 1988 D was assigned to the more restrictive prescription rules of opioids, which further reduced the number of deaths. The reduction of D deaths was followed by a corresponding increase in deaths due to M. However, the demographic characteristics of D and M deaths were not entirely identical: The typical D victim had a history of psychiatric disease or drug/alcohol abuse and committed suicide; the age was 40-59 for women and 20-39 for men. The typical M victim also had a history of psychiatric disease and substance abuse but suicides were less common and the majority occurred in the age group 20-39 in both sexes. Both D and M deaths were rare in persons with a somatic secondary diagnosis. We conclude that these poisonings warrant continued attention, and that a more restrictive prescription practice of D and M to patients at risk is justified.

Adolescent↗