Biomedical subjects

Marcus Hörmann

Publications and source records attributed to Marcus Hörmann.

14 recordsLinked to original sources

PubMed2006

MRI investigation of normal fetal lung maturation using signal intensities on different imaging sequences.

To purpose of this paper is to study the relation between normal lung maturation signal and changes in intensity ratios (SIR) and to determine which magnetic resonance imaging sequence provides the strongest correlation of normal lung SIs with gestational age. 126 normal singleton pregnancies (20-37 weeks) were examined with a 1.5 Tesla unit. Mean SIs for lungs, liver, and gastric fluid were assessed on six different sequences, and SIRs of lung/liver (LLSIR) and lung/gastric fluid (LGSIR) were correlated with gestational age for each sequence. To evaluate the feasibility of SIRs in the prediction of the state of the lung maturity, accuracy of the predicted SIRs (D*) was measured by calculating relative residuals (D*-D)/D for each sequence. LLSIRs showed significant changes in every sequence (p<0.05), while LGSIRs only on two sequences. Significant differences were shown for the mean of absolute residuals for both LLSIRs (p<0.001) and for LGSIRs (p=0.003). Relative residuals of LLSIRs were significantly smaller on T1-weighted sequence, whereas they were significantly higher for LGSIRs on FLAIR sequence. Fetal liver seems to be adequate reference for the investigation of lung maturation. T1-weighted sequence was the most accurate for the measurement of the lung SIs; thus, we propose to determine LLSIR on T1-weighted sequence when evaluating lung development.

Feasibility Studies↗

PubMed2006

Fetal MRI of the urinary system.

The assessment of the urinary system is typically performed by ultrasound. Nevertheless, an ultrasound may be inconclusive in fetuses with renal diseases that result in anhydramnios or oligohydramnios. In such cases, and in other cases in which ultrasound is limited, further investigation with MR should be considered. In the following article, we will provide an overview of the most commonly encountered disorders of the urinary system and their appearance on fetal MR imaging. Fetal MR imaging can accurately diagnose a wide variety of urinary tract disorders and must be seen as a valuable complementary tool to ultrasound in the assessment of the urinary system, particularly in cases of inconclusive ultrasound findings.

Female↗

PubMed2006

Normal renal development investigated with fetal MRI.

OBJECTIVE: To evaluate age-dependent changes in fetal kidney measurements with MRI. PATIENTS AND METHODS: Fetal MRI examinations were used to study the kidney length (218 fetuses), signal intensities of renal tissue, renal pelvis, and liver tissue on T2-weighted images (223 fetuses), and the whole-kidney apparent diffusion coefficient (107 fetuses). A 1.5 T superconducting unit with a phased array coil was used in patients from 16 to 39 weeks' gestation. The imaging protocol included T2-weighted single-shot fast spin-echo, T2-weighted balanced angiography and diffusion-weighted sequences. Slice thickness ranged from 3 to 5mm. RESULTS: Fetal kidney length as a function of gestational age was expressed by the linear regression: kidney length (mm)=0.190 x gestational age (d) -8.034 (R(2) = 0.883, p < 0.001). Paired t-test analysis showed a highly statistically significant difference between the ratio of renal tissue signal intensity to renal pelvis signal intensity and the ratio of liver signal intensity to renal pelvis signal intensity on T2-weighted images (t = -50.963, d.f. = 162, p < 0.001), with renal tissue hyperintense to liver tissue. The apparent diffusion coefficient in relation to gestational age was described by the equation: ADC (microm(2)/s) = 0.0302 x square (gestational age (d)) -14.202 x gestational age (d) +2,728.6 (R(2) = 0.225, p < 0.001). CONCLUSION: The length, signal intensity on T2-weighted images, and apparent diffusion coefficient of the fetal kidney change significantly with gestational age. The presented data may help in the prenatal diagnosis of renal anomalies.

Female↗

PubMed2004

The effect of varying low-dose protocols on perceived image quality in multidetector CT in a rabbit model of acute appendicitis.

The aim of this study was to evaluate the value of multidetector CT (MD-CT) with low-dose protocols in the diagnosis of acute appendicitis in a rabbit model. Ten New Zealand white rabbits underwent ligation of the appendix. MD-CT (Siemens Somatom Plus 4 Volume Zoom) was performed using three low-dose protocols: 80 kV/70 mAs; 80 kV/50 mAs; and 80 kV/20 mAs. Axial and coronal reformations were performed. Three experienced radiologists evaluated the images using a four-grade score: (1) excellent; (2) good; (3) moderate; and (4) not sufficient. Diagnosis was confirmed histopathologically. The overall score for the 80 kV/70 mAs was 1, for the 80 kV/50 mAs protocol 1.3, and the 80 kV/20 mAs protocol reached an overall score of 2. The coronal reformations reached with 1.1 (80 kV/70 mAs), 1.2 (80 kV/50 mAs), and 1.4 (80 kV/20 mAs) had a slightly better median score than the axial reconstructions. In cases of inconclusive ultrasound and clinical presentation, the use of MD-CT can be considered when evaluating children for suspected appendicitis.

Acute Disease↗

PubMed2004

Imaging of the scrotum in children.

Clinical examination of the scrotum is difficult due to the small size of the testes and the epididymis in infants and young children, and eliciting patients' history is challenging. Therefore imaging of the scrotum in childhood bears great importance. Ultrasound is the standard imaging technique of choice providing the clinicians with a definitive diagnosis in most cases. However, in conditions of testicular torsion and epididymoorchitis--the most common differential diagnosis of scrotal pain--ultrasound findings can be inconclusive and further evaluation is required. Since there is a large overlap between paediatric and adult pathology, differences from adults in anatomy and pathology must be considered when evaluating the paediatric scrotum.

Child↗

PubMed2003

Longitudinal observation of antenatally detected congenital lung malformations (CLM): natural history, clinical outcome and long-term follow-up.

OBJECTIVE: The objective of the study is to present longitudinal observations in antenatally detected congenital lung malformations (CLM), particularly pulmonary sequestration (PS) and cystic adenomatoid malformation (CAM). METHODS: Fetuses found to have a CLM on prenatal ultrasound (US) were included in this study and followed up until delivery. In all newborns radiographs and computerized tomography (CT) studies of the thorax were performed. Surgical procedures included sequesterectomy, lobectomy, segmentectomy, and non-anatomic resection. Based on prenatal US findings, intrauterine course, postpartum chest radiographs and CT scans, as well as clinical signs and surgical findings patients were divided into six groups. RESULTS: Over a period of 6 years, routine prenatal US revealed suggestion of CLM in a series of 35 consecutive fetuses. In six cases pregnancy was terminated or the fetuses suffered fetal demise. Another four fetuses became symptomatic in utero when sequential scanning revealed hydrops, hydrothorax, and enlargement of cysts or polyhydramnios. Three cases in this group received serial therapeutic amniocentesis and serial puncture of either the hydrothorax or intrapulmonary cysts. After postpartum treatment in the intensive care unit surgical procedures were performed uneventfully and confirmed the diagnosis of CAM, PS or hybrid type lesions. In 11 patients US findings were considered to demonstrate spontaneous resolution of the lesion, but disappearance without sequelae could be confirmed only in six infants. Five infants were shown to have persistent CLM on postpartum CT scans. These infants underwent resection of the lesion within the first year of life. In 11 fetuses CLM were continuously demonstrated during pregnancy with only slight changes in size and structure. Postpartum the infants were asymptomatic and were subjected to a systematic plan of diagnostic work-up and treatment. Surgery in these infants revealed a large number of hybrid type lesions (n=5). In three infants, the primary diagnosis of PS or CAM had to be corrected during the diagnostic and therapeutic work-up. CONCLUSION: CLM are diagnosed antenatally with an increasing frequency and are shown to be quite different from previously applied concepts. The expected clinical outcome is far better than thought to be possible.

Abortion, Legal↗

PubMed2003

Three-dimensional volume rendering of multidetector-row CT data: applicable for emergency radiology.

Multidetector-row computed tomography (MD-CT) not only creates new opportunities but also challenges for medical imaging. Isotropic imaging allows in-depth views into anatomy and disease but the concomitant dramatic increase of image data requires new approaches to visualize, analyze and store CT data. The common diagnostic reviewing process slice by slice becomes more and more time consuming as the number of slice increases, while on the other hand CT volume data sets could be used for three-dimensional visualization. These techniques allow for comprehensive interpretation of extent of fracture, amount of dislocation and fragmentation in a three-dimensional highly detailed setting. Further more, using minimal invasive techniques like CT angiography, new opportunities for fast emergency room patient's work up arise. But the most common application is still trauma of the musculoskeletal system as well as face and head. The following is a brief review of recent literature on volume rendering technique and some exemplary applications for the emergency room.

Angiography↗

PubMed2003

First experiences with multidetector CT in traumatized children.

INTRODUCTION: The aim of this study was to describe and discuss first experiences with multidetector CT (MDCT) in the assessment of traumatized children. MATERIAL AND METHODS: Since the implementation of a MDCT scanner in April 2002, 85 children (31 girls, 54 boys with a mean age of 9.2 years) consecutively underwent MDCT (Siemens, Erlangen, Germany) with different protocols depending on age, weight, trauma mechanism and clinical presentation. In all patients in whom pathology was suspected, multiplanar reformations (MPR) in coronal and or sagittal orientation was performed. Examinations were evaluated by two radiologists retrospectively and in consensus. RESULTS: In 55 (65%) children, a MDCT solely of the head was performed, in 46 there was no pathology found. In six (7%), head and facial bones were scanned. Head and abdomen was examined in two (2%), in two (2%) the abdomen only and in one (1%) the pelvis solely. Scans of the spine were obtained in seven (8%) children. A thorax and abdomen examination only was obtained in one (1%) child each. In 11 (13%) children, a polytrauma protocol was performed. In all patients, the time of examination did not exceed 17 min, including setup time. All children survived at the writing of this report. CONCLUSION: MDCT was promising in the management of traumatized children and seems to shorten the necessary time to reach diagnosis and to initiate life-saving treatment.

Child↗

PubMed2003

Correlative high-resolution MR-anatomic study of sciatic, ulnar, and proper palmar digital nerve.

Aim of this study was o evaluate the effectiveness of high-resolution MR imaging in demonstrating the anatomic structure of peripheral nerves of different diameter and composition. The dissected sciatic, ulnar, and proper palmar digital nerve of fresh cadavers were imaged at pre-selected landmarks on a 3T MR scanner. The nerves were then embedded in formalin, sliced, stained, and microscopically analyzed. The size, shape, and signal intensity of the sheath and axonal structures in the nerves at the landmarks were identified in MR images by comparison with histologic sections. The fascicles were clearly distinguished and counted in all specimens with MR imaging and showed only small differences from the histologic evaluation. High resolution MR imaging has the potential to visualize the fascicular structure in nerves of all sizes, which may be helpful in the preoperative assessment.

Fingers↗

PubMed2003

Cystic echinococcosis of the thyroid gland in children and adults.

In humans, cystic echinococcosis is one of the most serious helminthic diseases worldwide. The larval stages (cysts) of Echinococcus granulosus are mainly located in the liver and the lung. Other locations of infection are rare, which may occasionally hinder its diagnosis. A 14-year-old girl from Kosovo presented with a cystic lesion in the left thyroid lobe of 4 years duration. Although two percutaneous punctures had been performed, she developed a recurrence and therefore had to undergo thyroid surgery. The results of the histopathologic examination revealed a hydatid cyst, and consequently, the patient received a long-term course of medication, namely, albendazole. Imaging of the cranium and chest were normal. A computed tomography of the abdomen detected a further cyst in the liver which did not show the typical signs of cystic echinococcosis. An echinococcus cyst in the thyroid gland is rare, especially in children. In a review of the literature published since 1965, only 12 children have been reported. Although by definition percutaneous drainage is contraindicated to avoid the spread of protoscolices, it is documented in eleven patients without complications. Surgical extirpation is mandatory. Chemotherapy with benzomidazole derivatives is necessary to avoid recurrence.

Adolescent↗

PubMed2003

US as a primary diagnostic tool in relation to negative appendectomy: six years experience.

PURPOSE: To evaluate the effect of ultrasonography (US) on the rate of appendectomy after false-positive diagnosis of acute appendicitis (negative appendectomy). MATERIALS AND METHODS: Data were analyzed in 736 pediatric patients (mean age, 13.2 years) who had undergone appendectomy between 1995 and 2000. Histologic data were compared in patients who underwent US with those who did not undergo imaging prior to surgery. US was performed by a radiologist or a pediatric surgeon or both. RESULTS: A total of 643 (87.4%) of the 736 pediatric patients underwent preoperative US, and 93 (12.6%) of the 736 did not undergo preoperative US. Of the 736 patients, 97 (13.2%) underwent negative appendectomy. Thirty-four (36.6%) of the 93 patients who underwent appendectomy with no preoperative US and 63 (9.8%) of the 643 patients who underwent preoperative US underwent negative appendectomy. There was a significant association between US and positive appendectomy (P <.001). CONCLUSION: US in pediatric patients suspected of having appendicitis can significantly lower the negative appendectomy rate.

Adolescent↗

PubMed2003

[Imaging of diseases of the thyroid gland in Austria].

Imaging techniques for first line investigation of diseases of the thyroid gland are sonography (US) and scintigraphy, followed in dedicated cases by magnetic resonance imaging (MRI). Malignant lesions are generally hypoechoic on US with calcifications visible in some cases. The appearance of lymph node metastases is similar to that of the primary tumour. The various forms of goiter are the most commonly occurring forms of thyroid diseases in Austria, they appear heterogenous with hyperechoic as well as hypoechoic or anechoic nodes, in some cases with calcification. US findings of thyreoiditis are in acute forms of the disease more hypoechoic with diffuse swelling and hyperechoic with scar formations in chronic forms. Ectopic thyroid tissue occurs often in the form of thyroglossal duct cysts which are anechoic or hypoechoic.

Austria↗

PubMed2003

[Imaging of the parathyroid gland].

Diseases of the parathyroid gland are rare and are especially in case of hyperparathyroidism associated with hyperacalcaemia. Enlarged glands are, therefore, generally not detected with imaging modalities. The aim of imaging studies is to locialize abnormal glands. Ultrasound is the modality of choice for the primary investigation followed by nuclear medicine studies. Computed tomography or angiography with vein sampling should only be performed if the results of other investigations are equivocal. Magnetic resonance imaging is performed rarely in Austria with its high prevalence of endemic goiter.

Adenoma↗

PubMed2002

Ultrasound of the appendix in children: is the child too obese?

The negative influence of obesity on the detection rate of the appendix for US in adults has been reported. It has been assumed that obesity is a limiting factor in the detection of the appendix with US in children as well, but this has not yet been proven. The aim of our study was to evaluate whether nutritional condition (defined by the body mass index-for-age percentiles: BMI-FAP) influences the detection of the appendix in children on US. One hundred twenty-six children (65 girls and 61 boys) with a mean age of 11.4 years with clinically suspected acute appendicitis underwent ultrasound on a commercially available high-end machine (HDI 5000, ATL, Bothell, Wash.). The BMI was calculated, and children were divided in three weight groups in accordance with the BMI-FAP, and were correlated with US findings. Evaluation of the three weight groups in accordance with the BMI-FAP demonstrated significant differences ( p=0.04) in the detection of the appendix. There was no statistical significance for the BMI, weight, height, and age solely for the detection of the appendix. In children there is a correlation between the nutritional condition as defined by the BMI-FAP and the detection of the appendix.

Acute Disease↗