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Biomedical subjects

U Mödder

Publications and source records attributed to U Mödder.

At least 55 records · Page 3Linked to original sources
PubMed2002

Early postoperative tissue harmonic sonography of the thyroid gland.

PURPOSE: Fundamental gray-scale imaging (FGI) is known to be unuseful for thyroid imaging in the early postoperative setting. Thus, we evaluated the feasability of tissue harmonic imaging (THI) early after thyroid resection. MATERIAL AND METHODS: FGI and THI of the neck were performed in 48 consecutive patients 4 days after surgery. The examiner was blinded to patient diagnoses and types of surgery. FGI and THI examinations were stored on videotape and reviewed offline by two different readers who rated the quality of delineation of the organ borders and presence or absence of focal lesions. The results were compared to neck US performed 12 weeks after surgery. RESULTS: Delineation of the thyroid remnants in THI/FGI was rated to be excellent in 22/2, good in 11/9, poor in 3/16 and not visible at all in 4/13 patients. The correlation between THI-volumetry and control-volumetry was very high (r=0.81; p<0.0001). THI but not FGI depicted presence or absence of solid thyroid nodules with 100% accuracy. CONCLUSION: THI is a feasible method for thyroid US in the early postoperative setting. It permits volumetry of the residual thyroid tissue and accurately depicts nodules within the thyroid remnant.

Female↗
PubMed2002

Contrast-enhanced MR urography in the evaluation of renal transplants with urological complications.

AIM: The diagnostic work-up of renal transplants with impaired function due to urological problems can be difficult. This study was performed to assess sensitivity and specificity of non-invasive contrast-enhanced MR urography (MRU). METHODS AND MATERIALS: Thirty-five patients with renal transplants (25 - 71 years, mean: 53.4 years) with sonographically diagnosed hydronephrosis or perirenal fluid collections were assessed by MR urography. MR examinations were carried out at a 1.5 T clinical scanner (Vision, Siemens, Erlangen, Germany) with a 512 matrix contrast-enhanced fat-suppressed T1-weighted FLASH 3D sequence in breath-hold technique. MIP reconstructions were used to produce MR urography. MRU diagnoses were compared to operative results. RESULTS: In all patients, images with sufficient contrast in the renal collecting system were obtained. Hydronephrosis was confirmed in 20 patients, 8 patients showed a different pathology while 7 had normal findings. Compared to operative results, sensitivity of MRU was 100% with a specificity of 78%, respectively. One ureteral stone was misdiagnosed as a stricture, and 2 suspected ureteral stenoses could not be found upon operation. CONCLUSIONS: Contrast-enhanced MR urography is a highly sensitive and specific non-invasive method to evaluate patients suspected of having typical post-transplant urological complications. It may replace invasive procedures such as antegrade pyelography in the pre-operative work-up.

Adult↗
PubMed2001

Radiation dose in dental radiology.

The aim of this study was to compare radiation exposure in panoramic radiography (PR), dental CT, and digital volume tomography (DVT). An anthropomorphic Alderson-Rando phantom and two anatomical head phantoms with thermoluminescent dosimeters fixed at appropriate locations were exposed as in a dental examination. In PR and DVT, standard parameters were used while variables in CT included mA, pitch, and rotation time. Image noise was assessed in dental CT and DVT. Radiation doses to the skin and internal organs within the primary beam and resulting from scatter radiation were measured and expressed as maximum doses in mGy. For PR, DVT, and CT, these maximum doses were 0.65, 4.2, and 23 mGy. In dose-reduced CT protocols, radiation doses ranged from 10.9 to 6.1 mGy. Effective doses calculated on this basis showed values below 0.1 mSv for PR, DVT, and dose-reduced CT. Image noise was similar in DVT and low-dose CT. As radiation exposure and image noise of DVT is similar to low-dose CT, this imaging technique cannot be recommended as a general alternative to replace PR in dental radiology.

Cervical Vertebrae↗
PubMed2001

Magnetic resonance imaging and miniarthroscopy of metacarpophalangeal joints: sensitive detection of morphologic changes in rheumatoid arthritis.

OBJECTIVE: To evaluate and characterize magnetic resonance imaging (MRI) findings in the metacarpophalangeal (MCP) joints of rheumatoid arthritis (RA) patients macroscopically, using miniarthroscopy (MA; needle arthroscopy). METHODS: The second MCP joint of the dominant hand of 22 RA patients (13 with various RA activities/stages; 9 with early RA [< or = 1.5 years' duration]) was examined by MRI followed by MA. Findings were evaluated by standardized semiquantitative measures of synovial and bony pathologic changes of the MCP joint, and were compared with the clinical and conventional radiologic findings. RESULTS: Erosions and pre-erosions were detected in 17 of 22 patients by MRI; 2 of the other 5 patients (all early RA) displayed bony changes on MA. All 10 joints with pre-erosions on MRI (grade I bony alterations on MRI) exhibited significant cartilaginous and bony pathology on MA. Synovial membrane pathology was detected in all but 1 patient by MRI and in all patients by MA, although findings of plain radiography were normal in 6 of the 22 patients and another 9 patients had a Larsen score of 1. Semiquantitative analysis of synovial findings of MRI revealed gadolinium diethylenetriaminepentaacetic acid enhancement as a significant marker of macroscopically varied synovial vascularity and hyperemia, both of which strongly correlated with clinical activity (as measured by the Disease Activity Score). The extent of synovitis/synovial proliferation shown by MA and MRI were significantly correlated with each other, but not with any other activity or damage parameter analyzed. CONCLUSION: In RA, both MRI and MA findings support early detection and staging of synovial changes. Ongoing longitudinal studies are aimed at evaluating the value of synovial proliferation as visualized by both methods.

Adult↗
PubMed2001

Proton MR spectroscopy of the lumbar spine in patients with glycogen storage disease type Ib.

Glycogen storage disease type Ib is an autosomal recessive inherited metabolic disorder resulting from deficiency of the microsomal glucose-6-phosphatase enzyme system. Six patients (three of which were treated with granulocyte colony stimulating factor) suffering from this disease were examined using image guided localized proton magnetic resonance (MR) spectroscopy. The relative signal intensities of water and lipid protons of the lumbar spine were determined. Comparison was made with iliac crest biopsies in the glycogen storage disease type Ib patients and localized proton MR spectroscopic values of the lumbar spine obtained by thirteen healthy volunteers. The data demonstrate for the first time that hypercellularity and myeloid hyperplasia in subjects with glycogen storage disease type Ib due to functionally impaired leucocytes results in a strongly increased water proton signal with a very low or absent lipid signal in localized proton MR spectroscopy. Upon granulocyte colony stimulating factor treatment, the water proton signal in the lumbar spine is not further augmented.

Adolescent↗
PubMed2001

Imaging diagnosis of retroperitoneal ganglioneuroma in childhood.

PURPOSE: To demonstrate the typical appearance of retroperitoneal ganglioneuromas on CT and MRI. MATERIALS AND METHODS: Retrospective analysis of diagnostic imaging (five CT scans, three MRI scans) in five children aged 3-15 years with the histological diagnosis of ganglioneuroma. RESULTS: The scans showed large (maximum 11 cm diameter), round or oval tumours with sharply defined margins. Intraspinal tumour involvement occurred in two cases. Comparing CTwith MRI, MRI was more accurate in defining the intraspinal involvement. The ganglioneuromas were hypodense on unenhanced CT and showed moderate enhancement with administration of contrast medium. In three patients, CT demonstrated tumour calcification with a disseminated speckled pattern. On T1-weighted MRI the tumours were homogeneous and hypointense, showing marked enhancement after gadolinium administration. On T2-weighted scans the tumours were hyperintense. CONCLUSION: At the time of diagnosis, retroperitoneal ganglioneuromas are generally large tumours that can be shown well by CT and MRI. The appearance on CT more readily suggests the diagnosis, but MRI is superior for documenting local or intraspinal tumour extension and lacks radiation load.

Adolescent↗
PubMed2001

Magnetic resonance imaging of bone marrow changes in Gaucher disease during enzyme replacement therapy: first German long-term results.

OBJECTIVE: Since 1991, enzyme replacement therapy (ERT) has been available for patients with Gaucher disease in Germany. The aim of this study was to analyse the MR pattern of bone marrow involvement and response to ERT in Gaucher disease type I. PATIENTS AND DESIGN: Thirty patients with Gaucher disease type I had MRI examinations prior to initiation of ERT with alglucerase/imiglucerase and during follow-up. Median MR follow-up and duration of ERT were 36 months. Coronal T1- and T2-weighted spin-echo images of the lower extremities were obtained to evaluate changes in the appearance of yellow marrow. MR images were categorized as having either a homogeneous (type A) or non-homogeneous patchy (type B) appearance of bone involvement and response to ERT was assessed by two radiologists. RESULTS: Overall, 19 of 30 patients (63%) showed an increased signal intensity on T1- and T2-weighted images after 36 months of ERT, consistent with partial reconversion of fatty marrow during treatment. Focal bone lesions surrounded by a low signal intensity (SI) rim did not respond to ERT, suggesting bone infarcts. Of the 11 patients with bone infarcts (low SI rim lesion), 82% had the non-homogeneous type B pattern (P=0.0021). In 86% of patients with splenectomy, bone infarcts were seen (P<0.05). CONCLUSIONS: MRI using T1- and T2-weighted spin-echo sequences is a valuable, non-invasive method for monitoring bone marrow response in patients receiving ERT. A non-homogeneous patchy signal intensity of bone marrow involvement correlates with the presence of bone infarcts (P=0.0021).

Adult↗
PubMed2001

Estimation of antithyroid drug dose in Graves' disease: value of quantification of thyroid blood flow with color duplex sonography.

The purpose of this study was to evaluate if there is an association between the antithyroid drug dose that is needed to establish euthyroidism and thyroid blood flow measurements. A total of 23 Graves' disease patients with euthyroidism taking antithyroid drug therapy were enlisted to undergo spectral duplex sonography of the thyroid arteries and color-flow mapping of the thyroid gland. Color pixel density (CPD) was calculated with computer assistance from the color-flow maps. There was a strong correlation between the CPD and methimazole dose (rp = 0.79). Methimazole maintenance dosage could be predicted from CPD values with a coefficient of determination of 0.62. In conclusion, CPD measurements could be a useful tool for the clinical endocrinologist to estimate the antithyroid drug dose that is needed to maintain euthyroidism.

Adult↗
PubMed2001

In vitro determination of cardiac ventricular volumes using MRI at 1.0 T in a porcine heart model.

PURPOSE: To determine the accuracy of a 1.0 T MR system with a standard gradient system for quantification of left and right ventricular volumes. A porcine heart model in vitro was used. METHODS: In eight explanted porcine hearts the atria were removed and the aorta and the pulmonary truncus were cannulated. Defined volumes were injected into the ventricles. Magnetic resonance imaging (MRI): FFE-EPI (Multishot EPI) was used. Papillary muscles and trabeculae were excluded. True volumes and MR measurements were analysed separately for both ventricles and by both investigators. RESULTS: The correlation of the true volumes and MR measurements was >0.99. MRI was found to be investigator independent in assessing right and left ventricular volumes in vitro. CONCLUSIONS: MRI at 1.0 T using standard equipment can be used to quantitate cardiac ventricular volumes in vitro with high accuracy.

Animals↗
PubMed2001

[Signal changes of the bone marrow in MRI under long-term treatment with granulocyte colony-stimulating factors].

PURPOSE: Recurrent infections in patients with glycogen storage disease (GSD) type Ib resulting from an associated neutropenia are frequently treated with granulocyte colony-stimulating factors (G-CSF). The aim of this study was to evaluate the changes occurring in bone marrow by magnetic resonance imaging (MRI) in these patients. MATERIAL AND METHODS: The distal femoral and tibial bones of six patients with GSD Ib were evaluated by MRI. Four of these patients were treated with G-CSF for at least 3.9 to a maximum of 8.2 years (mean 5.8 years). The imaging sequences encompassed spin-echo as well as short-time inversion recovery sequences. 4 of the 6 patients had bone marrow aspirations. RESULTS: The patients who had undergone therapy with G-CSF showed a marked increase in signal strength in STIR sequences which encompassed the entire medullar cavity. In T1-weighted images these areas were hypointense. Biopsies obtained from these patients showed a bone marrow hypercellularity. The patients without G-CSF therapy showed the same signal intensity changes but with a more discrete and localized pattern in the metaphyseal cavities. CONCLUSION: In subjects with GSD Ib, an increased myelopoetic activity of the bone marrow which is intensified under long-term treatment with G-CSF can be demonstrated by MRI.

Adolescent↗
PubMed2001

[Does tissue harmonic imaging allow early determination of postoperative thyroid volume?].

AIM: Therapy for endemic goitre after surgical resection depends on the residual thyroid volume. Post-operative changes have been known to impair the fundamental sonographic evaluation of residual thyroid tissue. It was our aim to determine whether THI is a feasible method for thyroid volumetry after surgery. METHODS: 48 patients underwent thyroidectomy, hemithyroidectomy, near total resection, or partial resection of the thyroid gland. In all patients THI of the neck was performed 4 (mean; range: 2-7 days) days after surgery using an Elegra sonographic device (Siemens, Erlangen, Germany) with a transmitted frequency of 3.4 MHz and received frequency of 6.8 MHz. The examiner was blinded to the patient's diagnosis and the type of surgery. The residual tissue volume measured by means of THI and intra-operative volumetry were both compared to sonographic volumetry 12 weeks after surgery, the latter serving as the gold standard. Accuracy of THI and intraoperative volumetry were tested for significant differences using a paired t-test. RESULTS: Volumetry by the surgeon was available in 26 patients (54%). The men error of THI volumetry was 2.4 ml (SD: 3.3 ml; maximum: 17 ml). The mean error of intraoperative volumetry was 1.4 ml (SD: 1.9 ml; maximum: 6 ml). The mean difference between THI and intraoperative volumetry was 1 ml (SD: 2.7 ml; maximum: 7 ml; p = 0.085). CONCLUSIONS: THI permits early volumetry of the residual tissue after thyroid surgery comparable with the intraoperative volumetry. Thus, THI may be helpful in guiding the substitution of thyroid hormones.

Adult↗
PubMed2001

[MRI of the cerebellopontine angle in patients with cleidocranial dysostosis].

PURPOSE: Cleidocranial dysostosis (CCD) is an autosomal dominant bone disorder in which deafness is common secondary to malformation of the middle ear structures. The study aimed at MRI evaluation of the cerebellopontine angle in 7 patients with a history of CCD--two generation spanned relatives. MATERIAL AND METHODS: Cranial MRI in 7 patients with CCD (4 women/3 men aged between 8 and 46 years) was performed. In two patients hearing disorders were present. The examinations encompassed multi-planar spinecho sequences of the cerebellopontine angle in 3-mm slice thickness before and after administration of contrast medium. RESULTS: The clinically most conspicuous female patient (hearing loss, ataxia, headache) showed a strongly contrast-enhancing tumor in MRI that was histologically proved to be an acoustic schwannoma. Concerning the other family members, no pathological findings were noted except for non-pneumatized mastoids. CONCLUSION: The first report of a patient with CCD and an acoustic schwannoma shows that in case of hearing loss in these patients also a retrocochlear cause must be considered.

Adolescent↗
PubMed2001

[Real-time compound imaging: improved visibility of puncture needles and localization wires as compared to single-line ultrasonography].

AIM: To compare the visibility of biopsy needles and localization wires using real-time compound imaging (SonoCT) and single-line ultrasound (SLU). METHODS: 14-18 G biopsy needles and 5 different localization wires with and without puncture needle were placed into cadaverous muscle in 4 different angulations (0, 12, 18 and 25 degrees). Sonography was performed with an ATL HDI 5000 sonography device with a 5-12 MHz linear array using single-line ultrasound and compound imaging with 3 and 9 frames (Comp3 and Comp9) from different viewing angles. Images of the needles were obtained in the longitudinal plane without changing depth, focus position, and gain settings between the measurements. The mean grey values of the needle (gv_n) and of the background (gv_b) were obtained from histograms. Contrast was calculated using the equation (gv_n-gv_b)/gv_b + gv_n). Mean contrast in single-line and compound images was compared for each angulation using a Student t-test. RESULTS: The mean contrast at 0 degree was 0.686 in single-line ultrasound. This was significantly higher than in Comp3 (0.62) and Comp9 (0.633) (p < 0.05) images. At 12 degrees no significant differences could be observed. At 18 degrees image contrast was significantly higher in compound images with 0.493 (Comp3) and 0.498 (Comp9), compared to SLU (0.433) (p < 0.05). At 25 degrees the difference between compound images (Comp3: 0.394; Comp9: 0.402) and SLU (0.306) was greatest (p < 0.0001). CONCLUSION: At 0 degree and 12 degrees visibility is very good for all tested materials. For steeper angulations contrast was partly critical in SLU and significantly enhanced with compound imaging. Thus, SonoCT may be useful to increase precision of ultrasound-guided percutaneous interventions.

Animals↗
PubMed2001

Radiation exposure in multi-slice CT of the heart.

PURPOSE: To assess radiation exposure of patients undergoing Multi-Row Detector CT (Multi-Slice CT, MSCT) of the heart. MATERIAL AND METHODS: Four different cardiac MSCT protocols with changing slice collimation (4 x 1, and 4 x 2.5 mm), and pitch-factor (1.5, 1.8, and 4) were examined. An anthropomorphic Alderson-Rando phantom was equipped with LiF-thermoluminescent dosimeters at several organ sites, and effective doses were calculated using ICRP-weighting factors. These data were compared to data from standard MSCT of chest and abdomen. RESULTS: Effective dose in different protocols for cardiac MSCT varies from 2.8 to 10.3 mSv (male), and from 3.6 to 12.7 mSv (female). In protocols with thin collimation and low pitch or a combination of several heart examinations, radiation exposure may be comparable to the effective dose of standard MSCT of the chest (male: 11.9 mSv, female: 12.9 mSv) or the abdomen (male: 16.1 mSv, female: 15.7 mSv). Highest organ doses were found for the female breast (up to 46.6 mGy), and the lungs (up to 36.4 mGy) with surface doses as high as 54.3 mGy. CONCLUSIONS: Cardiac MSCT adds significantly to the radiation exposure of patients and can reach the effective dose applied by standard MSCT of chest or abdomen.

Bone Marrow↗
PubMed2001

[MR-morphological changes of the metacarpophalangeal joints in patients with rheumatoid arthritis: Comparison of early and chronical stages].

UNLABELLED: MR-morphological changes of the metacarpophalangeal joints in patients with rheumatoid arthritis: Comparison of early and chronical stages. PURPOSE: Evaluation of MRI findings in the metacarpophalangeal (MCP) joints in patients with early (eRA) and chronical rheumatoid arthritis (cRA). MATERIAL AND METHODS: In 22 RA patients (9 with disease duration </= 1.5 years = eRA) the dominant hands were examined by MRI in coronal T(2) weighted turbo-spin-echo (TSE). T(1) weighted spin-echo (SE) sequences before and after injection of Gd-DTPA and fat-suppressed short tau inversion recovery (STIR) sequences, followed by miniarthroscopy (MA) of the MCP II joint after an interval of 24 hours. MRI and MA findings were assessed using standardised semiquantitative items of synovial and bony pathologies and a statistical comparison between eRA and cRA patients was performed. RESULTS: In MRI synovial proliferation was detected in 13/13 cRA and 8/9 eRA patients. It was statistically not significant; the degree of synovial proliferation was however lower in the eRA group. All eRA patients with synovial changes showed enhancement after administration of contrast medium, a marker which correlated with the clinical activity. In 2/13 cRA patients no uptake of contrast medium was evident. Bony erosions and strongly narrowing joint space correlated with disease duration and were documented significantly rarer in the eRA patients (1/9, 2/9) than in the cRA patients (9/13, 10/13). CONCLUSION: In RA patients, MRI of the metacarpophalangeal joints can detect specific pathological changes which are observed significantly more often in either early or chronic stages and which are associated with disease activity and duration.

Adult↗
PubMed2001

[Gaucher disease: MR evaluation of bone marrow features during treatment with enzyme replacement].

PURPOSE: Enzyme replacement therapy (ERT) arrests and reverses the hematological and visceral symptoms of adult Gaucher disease, the most frequent lysosomal storage disorder. There are only a few studies available evaluating bone disease during ERT. The aim of this study was to investigate the features of bone marrow (bm) by magnetic resonance imaging (MRI) in these patients during ERT. MATERIALS AND METHODS: MRI was performed prospectively in thirty adult type I Gaucher patients before and during ERT with a mean follow-up of 3 years. Spin-echo sequences (T(1)/T(2)) of the lower extremities were obtained and the reconversion (response) or lack of reconversion (non-response) to fatty marrow during treatment was analyzed. The morphological features of bm involvement, a homogeneous or non-homogeneous distribution of bm changes and focal bone lesions surrounded by a rim of reduced signal intensity (SI), were analyzed. RESULTS: Infiltration of bm by Gaucher cells is characterized by a reduction of SI on both T(1)- and T(2)-weighted sequences. Bone marrow responses were seen in 19 patients (63 %) during treatment. Focal bone lesions, surrounded by a rim of reduced SI, did not respond to ERT and correlated with a non-homogenous distribution of bone involvement and splenectomy. CONCLUSION: In adult patients with type I Gaucher disease receiving ERT, treatment effects on bone disease can be demonstrated by MRI using Spin-echo sequences due to the partial reconversion of fat marrow. A non-homogeneous type of signal appearance and a status post splenectomy correlate with the presence of bone infarcts.

Adult↗
PubMed2001

Noninvasive investigation for renal artery stenosis: contrast-enhanced magnetic resonance angiography and color Doppler sonography as compared to digital subtraction angiography.

INTRODUCTION: The question about the most appropriate non-invasive method for detecting a renal artery stenosis (RAS) when comparing contrast enhanced magnetic resonance angiography (MRA) and color Doppler sonography (CDS) is still under discussion. Therefore we conducted a prospective study in order to evaluate both methods as compared to digital subtraction angiography (DSA). PATIENTS/METHODS: Thirtysix consecutive patients (53,9 +/- 13,7 years) with suspected RAS were investigated. MRA was performed using gadolinium for contrast enhancement. CDS was performed using a 2.5 and 3,5 MHz transducer. A peak systolic velocity (Vmax) >200 cm/sec within renal arteries and/or a side to side difference of the resistive index (RI) of >0,05 were used to discriminate stenosis. A diameter reduction of > or = 60% by DSA was considered a stenosis relevant to the patient. RESULTS: Sixty-eight main renal arteries and 9 accessory vessels were detected by DSA. Twenty main and 3 accessory arteries were found to be stenosed > or = 60%, while 4 main and 1 accessory artery presented with occlusion. MRA detected 70 renal vessels (65 main and 5 accessory arteries). Twenty-one stenosed arteries and 4 occluded vessels were correctly diagnosed by MRA. With CDS 68 renal vessels (62 main and 6 accessory arteries) could be visual- ized out of which 21 stenoses were diagnosed because of increased Vmax and 6 stenoses were detected because of a side to side difference of RI. For main renal arteries sensitivities and specificities were 96% and 86% for MRA and 96% and 89% for CDS. CONCLUSIONS: MRA and CDS are both comparable methods for detection of a renal artery stenosis > or = 60%. Despite several limitations, CDS can at the moment still be favored as a screening method.

Adult↗