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Biomedical subjects

G Bongartz

Publications and source records attributed to G Bongartz.

At least 73 records · Page 4Linked to original sources
PubMed1995

[In vitro validation of intravascular ultrasound, computerized and magnetic resonance tomography in diagnosis of atherosclerotic vascular segments in comparison with direct magnification radiography].

The depiction of atherosclerotic vessel abnormalities is a prerequisite for percutaneous interventional therapy and long-term observations of peripheral artery disease. The aim of this in-vitro study was to determine the potentials and limitations of 12.5 and 20 MHz intravascular ultrasound, computed tomography and magnetic resonance (MR) imaging in comparison to direct magnification radiography for the localization and quantification of peripheral vessel wall calcifications. Forty-three postmortem, human iliac segments were examined by intravascular ultrasound (12.5 and 20 MHz), computed tomography and magnetic resonance tomography (gradient echo-and spin echo-technique). For comparative analysis, each segment was divided into eight sectors of 45 degrees each; using all five methods, the presence of calcified wall areas was examined in each sector, and luminal area (42 segments) and plaque area (32 isolated plaques) were quantitatively estimated. In the sonograms, the circumferential extension of the boundary between intima and media was measured. 122 of 344 sectors showed regional vessel wall calcifications. Sensitivity of 20 MHz intravascular ultrasound was 73% versus 59% with the 12.5 probe, specificity was 97% with 20 MHz, 96% with 12.5 MHz. Sensitivity of both 12.5 and 20 MHz intravascular ultrasound was higher with increased thickness of the calcified structures. 20 MHz ultrasound identified the intima-media boundary averaging 146.8 degrees of the vessel circumference; the corresponding value of 131.8 degree with 12.5 MHz did not differ significantly. Computed tomography detected calcifications with a sensitivity of 88%, specificity was 88%. With MR imaging, sensitivity of the gradient echo-technique was 94% versus a sensitivity of 86% with spin echo-technique. Quantification of luminal and plaque areas showed that luminal area was precisely estimated only by 20 MHz ultrasound (no significant difference to direct magnification radiography), whereas all other techniques showed significant overestimation. Plaque areas were markedly overestimated by computed tomography and MR imaging, too. In an in vitro set-up, intravascular ultrasound, MR tomography and computed tomography do not allow an authentic depiction of peripheral vessel wall architecture. Limited resolution, subintimal shadowing and and distortion are the main limitations of these new techniques so that details of regional vessel wall calcifications cannot be presented thoroughly. Relevant over-estimation of luminal and plaque areas must be considered.

Arteriosclerosis↗
PubMed1994

Initial feasibility studies using single-shot EPI for the detection of focal liver lesions.

Echo planar MR imaging (EPI) has been developed to completely eliminate motion artifacts and is currently being prepared for implementation into clinical MR systems. Thus, the purpose of this study was to evaluate the clinical utility of EPI in the detection of focal liver lesions and to compare EPI with in the detection of focal liver lesions and to compare EPI with contrast-enhanced CT. EPI studies were performed on an experimental 1.0 Tesla whole body system using fat-suppressed single-shot spin echo (SE) and inversion recovery (IR) pulse sequences. A total of 26 liver tumors in 12 patients scheduled for liver resection were prospectively examined and correlated with intraoperative ultrasound, surgery, and pathology as the gold standard. Quantitative analysis of EPI was performed by means of liver signal-to-noise and tumor-liver contrast-to-noise calculations. Diagnostic performance compared with contrast-enhanced CT was assessed by means of ROC analysis. Lesion-liver contrast was highest with EPI SE at a TE-time of 70 ms and this technique showed best lesion detectability as measured by area under curve (AUC) values. Among EPI techniques, the IR sequence with an inversion time of 300 ms to null the liver signal showed high lesion-liver contrast but all four reviewers reported problems assessing liver anatomy. Improved EPI techniques may prove useful for screening of focal liver lesions.

Adult↗
PubMed1994

[MRI in soft tissue tumors].

MRI has been shown to be very useful in the diagnostic work-up of soft tissue masses. Because of its multiplanar capability and excellent contrast resolution, MRI is the method of choice for identification of tumour extent and follow-up examinations of soft tissue lesions. Due to the unspecific appearance of most soft tissue tumours, MRI cannot replace biopsy for definitive determinations of the nature of the lesion (benign vs malignant) in the majority of cases.

Diagnosis, Differential↗
PubMed1994

[Magnetic resonance angiography of supra-aortic arteries].

MR angiography of the carotid system was found to be readily applicable due to the laminar and fast flow conditions in the supra-aortic arteries. Time-of-flight methods are superior to phase-contrast measurements for the investigation of atherosclerotic lesions. Recent developments in sequence design enable improvement of the MR angiographic results with respect to correct staging of stenotic alterations. Two-dimensional acquisitions are preferred in slow flow conditions with the disadvantage of decreased resolution, in-plane saturation effects, and poststenotic signal voids. In 3D MR angiography, the major advantage is improved resolution, although the saturation effects within the measurement volume must be compensated for either by sequential acquisition of multiple thin volumes or by the application of asymmetric excitation pulses. In a prospective trial with 50 patients, the advantages of a new type of rf-pulse (TONE) are demonstrated.

Blood Flow Velocity↗
PubMed1993

[Localization dependent patterns of findings in chondroblastoma].

In a retrospective study the radiographs of 48 chondroblastomas from the files of the Bone Tumour Registry of Westphalia were evaluated. The purpose of the study was to investigate whether chondroblastomas display localisation-dependent radiographic patterns. All radiographs were analysed using the Lodwick criteria. All chondroblastomas (mean age: 18 y., m:f = 1.25:1) showed a geographic pattern of bone destruction. 32 lesions affected long bones, 10 short bones, and 6 flat bones. Chondroblastomas localised in flat bones (Lodwick IA: 0%, IB: 33%, IC: 67%) demonstrated more aggressive patterns of bone destruction compared to lesions affecting long bones (Lodwick IA: 56%, IB: 31%, IC: 13%) or short bones (Lodwick IA: 40%, IB: 50%, IC: 10%). There was no difference between the three bone types in other radiographic patterns (periostitis, calcification, trabeculation).

Adolescent↗
PubMed1993

Polycystic disease of the kidneys complicating the diagnosis of myocardial echinococcosis.

The case of a 30-year-old woman with polycystic disease of the kidneys and a large cyst in the interventricular septum is presented. The hypothesis of an echinococcal disease or of a cardiac manifestation of a polycystic disease was raised. The patient's history, serologic data, and the morphological aspect of the cyst did not give evidence for echinococcal disease before surgery. However, the postoperative pathological evaluation confirmed the diagnosis of a single echinococcal cyst. The presented case shows that even in cases without proven diagnosis of echinococcal disease and preexisting hereditary cysts in other organ systems, care should be taken during surgery to avoid anaphylaxis and preoperative spread of the parasite throughout the body.

Adult↗
PubMed1992

[Magnetic resonance tomography of soft tissue tumors].

Soft tissue tumors are relatively often seen on MR tomography, although they make up a fairly small proportion of malignant lesions. To date, most soft tissue tumors have been investigated by MRI because of its unique soft tissue contrasts and its flexibility in slice orientation. But is MRI really adequate for staging and defining soft tissue tumors, or what role does it have pre-therapeutic work-up? Most malignant soft tissue tumors give rise to somewhat similar MRI findings and may not be sufficiently well characterized. On the other hand, some benign lesions can be clearly identified and staged. The goal of this paper is a critical discussion of the ability of MRI to define a lesion's degree of malignancy, to evaluate diagnostic criteria, and to describe requirements in the set-up of the investigation.

Humans↗
PubMed1991

[The place of magnetic resonance tomography in the diagnosis of diseases of the shoulder joint].

In a prospective study 43 patients with shoulder pain were examined by sonography and MRI. The findings were controlled by plain radiography, arthrography, and CT arthrography. Joint effusions and humeral head defects were equally identified by MR and sonography. In the diagnosis of labrum lesions, rotator cuff lesions, subacromial spurs, and synovial inflammatory disease sonography was not as accurate as MR. A special MR scoring system improved the diagnosis of an impingement syndrome.

Adult↗
PubMed1991

[MRT of the hypophysis: spin echo 2D or gradient echo 3D?].

Diagnostic efficacy of T1-weighted 3D gradient-echo and 2D spin-echo pulse sequences in the detection of adenomas were evaluated in a ROC study of 50 patients. Sensitivity, specificity and accuracy did not differ significantly, but in direct comparison gradient-echo received a clear lower rating due to susceptibility artifacts, lower signal-to-noise ratio, and inferior periglandular contrasts. Additional lesions could not be reliably detected in gradient-echo imaging at 1 mm slice thickness. A substitution of 2D spin-echo imaging by gradient-echo sequences cannot be recommended at present.

Adenoma↗
PubMed1991

Detection of hepatic masses in patients with carcinoma: comparative sensitivities of sonography, CT, and MR imaging.

To evaluate the sensitivity of sonography, CT, and MR imaging in the detection of hepatic masses in carcinoma patients, we conducted a prospective study of 75 consecutive patients with gastrointestinal tumors who were admitted for surgical resection of the primary tumor. Sonography was performed with convex transducers of 3.5 and 5.0 MHz. Three noninvasive CT techniques were used: unenhanced CT scans, the incremental bolus dynamic scanning technique, and delayed scanning 4-6 hr after bolus injection of 60 g of iodine. MR images (1.5 T) were acquired as presaturated T1- and T2-weighted spin-echo sequences and as breath-holding fast low-angle shot (FLASH) 60 degrees and FLASH 15 degrees sequences. As it is difficult to distinguish benign from malignant masses solely on the basis of morphologic criteria, the techniques for each imaging method were designed to detect and not to characterize hepatic lesions. Each examination was interpreted blindly, and the results were compared with surgical findings, intraoperative sonography, and biopsy of the liver as the gold standard. All focal hepatic masses verified at surgery, malignant or benign, were included in the analysis. Sixty-five (68%) of 95 focal hepatic masses were detected by CT, 60 lesions (63%) by MR, and 50 lesions (53%) by sonography. Although lesions 1-2 cm were shown almost equally well by CT and MR (74% and 77%, respectively), the detection rate of smaller lesions (less than 1.0 cm) decreased more drastically with MR (31%) than with CT (49%). Sonography had a sensitivity of only 20% with the smaller lesions. All imaging techniques had a sensitivity of 100% for focal hepatic masses larger than 2.0 cm. Our results show that CT has a higher overall sensitivity (68%) than MR and sonography for the detection of focal hepatic masses. When the results of the three procedures are combined, the overall sensitivity is 77%. This is unsatisfactorily low, as CT and MR have a size threshold of about 1.0 cm and are relatively unreliable for the detection of smaller lesions.

Adenocarcinoma↗
PubMed1991

[Hallervorden-Spatz syndrome. Indicative findings in cranial computerized and magnetic resonance tomography for intra vitam diagnosis].

We report the case of a female patient with a progressive therapy-resistant extrapyramidal movement disorder. Cranial computed tomography showed symetrical hyperdensities in the globus pallidus. The same areas are of decreased signal intensity in magnetic resonance imaging. These findings suggest an increased iron accumulation. The clinical symptoms and the radiological findings of the cerebrum are highly indicative for a Hallervorden-Spatz disease.

Adolescent↗
PubMed1991

[The diagnostic reliability of the occipitomental radiograph of the paranasal sinuses. Correlation with magnetic resonance tomography].

100 conventional occipitomental radiographs of the paranasal sinuses were studied independently by five radiologists. Predictive values were determined, based on MRI as the gold standard. Sensitivity and specificity for detection of mucosal thickening in the sinuses were: maxillary sinus: 0.73/0.76, frontal sinus: 0.20/0.85, ethmoid sinus: 0.38/0.87, sphenoid sinus: 0.14/0.96. In the maxillary sinus polypoid thickening was demonstrated with a significantly higher sensitivity than that of diffuse mucosal thickening (0.82 versus 0.65, Chi-square-test, p less than 0.01). Because of the low predictive values the occipitomental view is insufficient to assessing mucosal thickening in the paranasal sinuses, with the exception of polypoid mucosal thickening in the maxillary sinus.

Adult↗
PubMed1991

[Magnetic resonance tomography of the ankle joint].

To define the clinical role of MRI of the ankle joint, a total of 88 patients was investigated. In the evaluation of ligamentous injury, MRI was inferior to established imaging methods. By contrast, it provided additional therapy-relevant information in the assessment of hemophilic arthropathy, osteochondritis dissecans, and inflammatory and neoplastic diseases of the ankle joint. In the latter conditions, MRI may make other more conventional methods of examining the ankle joint unnecessary.

Ankle Injuries↗
PubMed1991

[Radiologic findings following supraglottic and total laryngectomy].

The treatment of carcinoma of the larynx has recently been greatly improved with the development of supraglottic and total laryngectomy. This has also led to a high five year survival rate. The normal postoperative radiological appearances are presented together with the spectrum of relevant radiological investigations and their indications. The most frequently seen postoperative complications and findings in patients with dysphagia are described with special reference to pharyngograms and cineradiography. The morphology of the vibrating segment after laryngectomy in patients who do not develop effective alaryngeal speech is demonstrated.

Cineradiography↗
PubMed1991

[The place of diagnostic imaging in xanthogranulomatous pyelonephritis].

The urographic, angiographic, sonographic and computed tomographic findings in 4 cases of xanthogranulomatous pyelonephritis are presented along with correlation with the pathological specimens. The parenchyma of the kidney was replaced by multiple, rounded, low-density respectively hypoechogenic areas on CT and sonography that corresponded to dilated calices and/or inflammatory tissue. For diagnosing the characteristic extrarenal extension of the disease sonography was not as accurate as CT.

Adult↗
PubMed1991

[Asymptomatic Moyamoya syndrome. Diagnosis by EEG and magnetic resonance angiography].

Alternating hemiplegias in children suggest the possibility of a Moyamoya syndrome. In the absence of clinical symptoms it is the EEG which will offer the decisive clue in childhood Moyamoya syndrome. The pertinent finding, which consists in progressive frequency decrease and amplitude activation after hyperventilation, has only been described in pediatric patients. It has been termed re-build-up phenomenon. Magnet resonance imaging and magnet resonance angiography (MR angiography) are able to confirm the tentative diagnosis of a Moyamoya syndrome based on the EEG.

Cerebral Angiography↗