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Biomedical subjects

F Dammann

Publications and source records attributed to F Dammann.

At least 37 records · Page 2Linked to original sources
PubMed1999

Inverted papilloma of the nasal cavity and the paranasal sinuses: using CT for primary diagnosis and follow-up.

OBJECTIVE: Morphologic criteria for the diagnosis of primary and recurrent inverted papilloma as revealed on CT were evaluated in a large series. MATERIALS AND METHODS: Findings of 121 CT examinations that had been performed in 32 patients with histologically proven inverted papilloma were retrospectively analyzed using the following morphologic criteria: localization, size, surface configuration, and bony changes. RESULTS: Unilateral tumor localization involving the lateral nasal wall and the middle meatus was the feature that best correlated with the finding of primary inverted papilloma. A lobulated surface pattern was another typical sign, which was revealed on 19 of the 29 CT scans of patients with primary inverted papilloma. Although tumor localization and the finding of a newly grown soft-tissue mass were less reliable criteria to differentiate between recurrent inverted papilloma and postoperative complications or concomitant inflammatory disease, a lobulated surface pattern was seen on 26 of the 28 CT scans of patients with tumor recurrence but on only three of the 64 follow-up CT scans of patients without recurrent inverted papilloma. CONCLUSION: A unilateral mass within the nasal cavity or paranasal sinuses with a surface configuration that appears lobulated on CT is, to our knowledge, a new sign that strongly suggests inverted papilloma as a primary diagnosis and also suggests inverted papilloma in patients with tumor recurrence.

Adult↗
PubMed1998

[Value of Schüller conventional roentgen diagnosis and computerized tomography of the temporal bone in preoperative diagnosis of the Tübingen implantable cochlear amplifier].

Recently, the transducer and microphone of a cochlea amplifier implant (CAI) for the treatment of sensorineural cochlear hearing loss have been developed further for implantation into the mastoid cavity. At present, the University of Tuebingen implantable cochlea amplifier consists of an implantable microphone and an implantable piezoelectric transducer. It has been implanted into the first patients. Successful future application of this new implant depends on the suitable fit of the CAI within a patient's mastoid cavity. Using conventional X-ray and CT scans, we analyzed 50 cadaver specimens of the temporal bone before total mastoidectomy. After total mastoidectomy, the volume of the mastoid cavity was measured using CT scans and water volume determination. Finally, the CAI was implanted into those temporal bones that were large enough to house it. Our results demonstrate that the degree of pneumatization in the conventional Schüller X-ray is already a good parameter for preoperative evaluation.

Cochlear Implantation↗
PubMed1998

High-resolution cardiac imaging using an interleaved 3D double slab technique.

A three-dimensional (3D) gradient-echo sequence with interleaved double-slab excitation was developed and optimized for the requirements in pediatric cardiac imaging. For this purpose high contrast between blood and myocardium signal should be obtained without the use of contrast agents. An acceptable measuring time for a large region examined with high spatial resolution should be achieved as well, especially with regard to the small structures of the heart and vessels of infants. The presented approach works with gradient moment nulling and a short echo time of 5.5 ms resulting in generally high signal intensity and only minor signal losses due to turbulent flow. The sequence allows simultaneous ECG-gated recording of two separately excited slabs with small thickness (10 mm) and with a distance of several centimeters between them. Thus, common effects of presaturation in 3D imaging can be avoided, although a relatively short measuring time is achievable. In order to get a 3D data set with good signal homogeneity of blood and of the other structures across a large volume of interest several double-slab measurements with suitable positions must be performed. The latter aspect is especially important for postprocessing techniques as multiple planar reconstruction and maximum intensity projection. Examples of applications of the new technique and appropriately postprocessed images are presented allowing demonstration even of subtle cardiac malformations.

Artifacts↗
PubMed1998

[Intra-arterial calcium stimulation for preoperative localization of insuloma].

PURPOSE: Objective is to evaluate the efficacy of the intraarterial calcium test in the preoperative localisation of insulinomas. MATERIAL AND METHOD: To stimulate the pathological release of insulin, calcium gluconate (0.015 meq Ca++/kg) was selectively injected into the arteries supplying the pancreas. Prior to calcium injection and 30, 60, 90 and 120 seconds later, 5 ml samples of blood were obtained from the right or from both right and left hepatic veins. Insulin levels were then determined by mean of immunoassays. A twofold increase in insulin level in the venous sample after 30 or 60 seconds localised the insulinoma to the region of the pancreas supplied by the selectively injected artery. Results of the calcium test were prospectively analysed in 6 patients and compared with operative findings. RESULTS: All 6 patients had a surgically proved solitary and benign insulinoma. Calcium stimulation with venous sampling provided true-positive localisation of insulinomas in all patients without suspicion of liver metastasis. All 6 patients currently have normal insulin levels after a mean period of 16 months (range 4-24 months) with no evidence of hypoglycaemia on fasting. CONCLUSION: Intraarterial stimulation with calcium and hepatic vein samplings for insulin gradients is a very sensitive minimally invasive functional method and may replace transhepatic portal venous samplings for the preoperative detection of insulinomas.

Adult↗
PubMed1998

Insulinoma and islet cell hyperplasia: value of the calcium intraarterial stimulation test when findings of other preoperative studies are negative.

PURPOSE: To evaluate the efficacy of the intraarterial calcium test in localizing sources of hyperinsulinism that remain undetectable at preoperative morphologic studies. MATERIALS AND METHODS: Twenty-four patients with clinically proved endogenous hyperinsulinism due to tumorous insulin production were prospectively enrolled. They underwent ultrasound (US), computed tomography, magnetic resonance imaging, endoscopic US, abdominal arteriography, and a calcium test, in which insulin concentrations were measured in hepatic venous blood after selective intraarterial calcium stimulation. The results of the calcium test in seven patients (five women, two men; age range, 30-66 years; mean age, 47 years) with negative findings of morphologic studies are described. RESULTS: Six solitary insulinomas (mean diameter, 0.73 cm) and one nodular hyperplasia were diagnosed after surgery. In all seven cases, calcium test findings allowed accurate localization of the pathologic source of insulin secretion. In three of these seven cases, results of arterial calcium stimulation with hepatic venous sampling (ASVS) affected intraoperative management. An increase in insulin concentration after stimulation in the hepatic artery was not observed, making hepatic metastases unlikely. CONCLUSION: ASVS, which is procedurally simpler than transhepatic pancreatic venous sampling, is effective for localizing sources of hyperinsulinism not detected with preoperative morphologic studies.

Calcium Gluconate↗
PubMed1997

Perianal complications of Crohn disease: MR imaging findings.

The aim of this study was to revisit anal anatomy, to explain surgical terminology in perianal complications of Crohn disease, and to show the MR imaging findings of perianal fistulas and abscesses. To this end more than 200 patients were studied using surface coils (Helmholtz; phased array) at 1.0 and 1.5 T. Transverse and coronal T1- and T2-weighted images were obtained. Parks' classification was used to describe perianal abscesses and fistulas. This pictorial essay shows the normal anal anatomy and pathologic findings such as subcutaneous, para-anal, ischiorectal, intersphincteric, and supralevatoric abscesses and fistulas. MR imaging with surface coils is well suited to showing the anal anatomy and to reliably describing perianal abscesses and fistulas according to surgical terminology.

Abscess↗
PubMed1997

[In vitro study of morphology of the bladder wall using MR tomography at 1.0 Tesla: correlation with histology].

PURPOSE: Evaluation of the potential of various MR techniques to differentiate bladder wall layers verified by histological findings. MATERIAL AND METHOD: 6 bladder specimens of pigs were examined in vitro using T1-weighted spin-echo-sequences, T2-weighted Turbo-SE, fat suppressed T2-weighted SE, and inversion recovery sequences. The MR images were obtained before and after fixating the specimens in formalin. Measurements of the thickness of bladder wall layers were performed on both sets of MR images as well as on histological sections, RESULTS: T2-weighted SE images showed three layers of different signal intensities: one innermost band of very high signal, one inner band of low and one outer band of intermediate signal corresponding histologically tunica propria and two different muscle layers. Inversion recovery technique provided similar findings but were able to avoid chemical-shift artifacts. After 24 hours in formalin, the signal intensity relation of the two muscle layers was inverted. The thickness of total bladder wall was not reduced significantly. Concerning the thickness of urinary bladder wall, histological measurements and evaluation of MR images correlated well. CONCLUSION: MR imaging enables the differentiation of three bladder wall layers. Inversion recovery technique achieved the best image quality by avoiding chemical shift artifact.

Animals↗
PubMed1997

[Value of dacryocystography in localization diagnosis of lacrimal duct stenosis].

PURPOSE: Evaluation of dacryocystography in the preoperative localisation of stenosis of the lacrimal passage. METHOD: The lacrimal system of 20 patients (25 eyes) suffering from lacrimal passage obstruction was examined either by conventional (n = 20) or by digital (n = 5) technique. Diagnostic imaging was evaluated concerning topographic Information of the pathologic lacrimal system, localisation of the level and differential diagnosis of the cause of the obstruction. RESULTS: Cause of the obstruction was chronic dacryocystitis (n = 16), dacryolithiasis (n = 1), atresia of the lacrimal duct (n = 2), posttraumatic lesions (n = 3), rhinosinusitis (n = 1) and carcinoma of the maxillary sinus (n = 1). In 23 of 25 cases (92%) we found an exact correlation between dacryocystography and the intraoperative findings. The variation of stenosis types as well as different examination techniques are presented and compared with literature findings. CONCLUSION: Dacryocystography is a valuable method in the diagnosis and preoperative planing in lacrimal system obstruction.

Adolescent↗
PubMed1997

MR imaging of the liver with Resovist: safety, efficacy, and pharmacodynamic properties.

PURPOSE: To evaluate the safety, efficacy, and pharmacodynamic properties of a new superparamagnetic parenteral iron oxide contrast agent for magnetic resonance (MR) imaging. MATERIALS AND METHODS: Thirty-six patients with liver lesions received a bolus injection of Resovist (SH U 555 A; Schering, Berlin, Germany) at a dose of 4, 8, or 16 micromol iron per kilogram body weight (micromol Fe/kg). Fast low-angle shot, spin-echo, and turbo gradient spin-echo MR images were obtained before and 10, 40, and 70 minutes after injection. Blood samples were obtained, vital signs were monitored, and adverse events were recorded. Lesion detection was assessed by two independent, blinded readers. RESULTS: No drug-related adverse events occurred. Serum iron and ferritin levels were increased at all dose levels. Partial thromboplastin time increased and factor XI level decreased 4 hours after injection of 16 micromol Fe/kg. Lesion detection and diagnostic confidence were increased in patients who received 4 or 8 micromol Fe/kg, with no further increase with a 16-micromol dose. CONCLUSION: Resovist is safe and effective. The best MR imaging results were obtained 40 minutes after injection of 8 micromol Fe/kg.

Adult↗
PubMed1997

Do mammography, sonography, and MR mammography have a diagnostic benefit compared with mammography and sonography?

OBJECTIVE: The purpose of our study was to assess the added value of MR mammography, mammography, and sonography compared with mammography and sonography in diagnostic evaluation of the breast. MATERIALS AND METHODS: We evaluated reports of MR mammography, conventional mammography, and sonography of the breast in 89 patients who had been referred for surgical biopsy. The dynamic MR mammography examinations were obtained on a 1.0-T MR imager using a double-breast coil and a three-dimensional axial fast low-angle shot sequence. Each type of study was interpreted by a different observer. All mammograms and sonograms were available to all observers. Without knowledge of biopsy results, observers classified mammograms and sonograms (which we call the standard method) as well as mammograms, sonograms, and MR mammograms (which we call the combined method). Classifications were on a per-breast basis: no disease; probably a benign or malignant lesion; and most likely a benign or malignant lesion. A classification of no disease or most likely a benign or malignant lesion was considered to represent a high confidence of the observer in the diagnosis. RESULTS: Of 98 breasts evaluated with the standard method, observer confidence was high for 44% of all malignant lesions versus 86% with the combined method. The highest specificity (92%) was achieved by interpretation of the standard method (combined method, 64%). The highest sensitivity (95%) was achieved by interpretation of the combined method (standard method, 83%). Overall accuracy was 87% for the standard method and 83% for the combined method. In separate analyses of nonpalpable and palpable lesions, the combined method achieved an accuracy of 74% for nonpalpable lesions and 88% for palpable lesions. The standard method achieved an accuracy of 85% for nonpalpable lesions and 88% for palpable lesions. CONCLUSION: MR mammography as an adjunct to mammography and sonography reveals breast cancer with a higher confidence and sensitivity than do mammography and sonography only. The combined method can be recommended if the greatest possible sensitivity or negative predictive value is wanted. However, the combined method is not useful for screening or workup of suspicious lesions because of its lower specificity and accuracy.

Breast↗
PubMed1995

Adapted techniques for clinical MR imaging of tendons.

To determine whether the echo time of magnetic resonance gradient-echo and spin-echo imaging sequences may be important for the occurrence of high signal strength from tendon with pathological alterations, imaging sequences with sufficient spatial resolution and very short echo times were developed for whole-body imagers with standard gradient system. The sequences were applied on the Achilles tendons of five healthy volunteers and seven patients with achillodynia. Some affected regions inside tendon, probably corresponding with tissue with subtle edema in the collagen bundles were only revealed in images recorded with very short echo times TE < 5 ms, whereas stronger affections and protons in liquids between the fiber bundles were also shown in images with longer echo times TE > 10 ms. Gradient-echo methods allow shorter echo times than spin-echo techniques for a given gradient system of the imager and given spatial resolution. So minimum echo time gradient-echo sequences should be used for sensitive imaging of tendon alterations, because no considerable signal dephasing due to susceptibility effects were found in tendon.

Achilles Tendon↗