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Biomedical subjects

N Hosten

Publications and source records attributed to N Hosten.

At least 109 records · Page 6Linked to original sources
PubMed1997

Uveal melanoma: detection of extraocular growth with MR imaging and US.

PURPOSE: To compare the sensitivity and specificity of magnetic resonance (MR) imaging with that of ultrasound (US) in the detection of extraocular extension of uveal melanoma. MATERIALS AND METHODS: In 70 patients, the diagnosis of melanoma and absence or presence of extraocular growth were confirmed with histologic examination (13 patients) or with ophthalmoscopy and surgery (57 patients). Unenhanced and enhanced T1-weighted and T2-weighted MR imaging was performed with surface coils at 1.5 T. A- and B-mode US scans were obtained with 8- and 10-MHz probes, respectively. RESULTS: Extraocular growth was confirmed in seven patients: Five patients had retrobulbar tumor, and two had optic nerve infiltration. US enabled detection in three cases, whereas six cases were diagnosed with MR imaging including both cases of optic nerve infiltration. False-positive findings were more frequent with US (n = 5) than with MR imaging (n = 1). CONCLUSION: MR imaging proved to be more sensitive and more specific than US in the detection of extraocular extension of uveal melanoma.

Eye Neoplasms↗
PubMed1997

["Second opinion" in online radiology via Internet: report on implementation and analysis of reliability of findings in sectional images].

Numerous medical on-line services have already been established in the world-wide internet. In connection with the Information service TELESCAN, sponsored by the EU, a pilot project has been initiated which offers a radiological "second opinion" via the transmission of radiological findings and images that have been previously rendered anonymous. In addition to a description of the basic implementation, tests of the diagnostic certainty of the transmitted cranial computed tomographs have been performed. The CT images were digitized with a document camera, transmitted over the Internet, and then evaluated on the receiver's monitor. Both the transfer of originally generated digital image files (in ACR-NEMA or DICOM) as well as graphic files after digitization of X-ray films, for example by a document camera, is possible via electronic post (e-mail). Visualization by the receiver requires the use of current proprietary software for special medical image formats, while standard graphic formats such as GIFF or JPEG can be visualized with the usual Internet software. In an ROC analysis, 56 individual images of cranial computed tomographs, half with pathological findings such as space-occupying lesions, infarcts, or brain edema, were tested with regard to the diagnostic certainty after digitization and transmission. In comparison with the original film findings, there was a slight but statistically not significant reduction in diagnostic certainty of the images evaluated on screen after transfer via the Internet. We believe that this result is due to the low local resolution, low dynamic range, the high image noise and of CT arising from the window technique. The same parameters are probably valid for MRI. The result cannot be applied to conventional radiography including mammography because, in comparison to the mentioned image techniques, their local resolution is high and image noise is considerably lower.

Computer Communication Networks↗
PubMed1997

MR of the eye with retrobulbar anesthesia.

MR imaging with retrobulbar anesthesia was performed in eight patients with uveal melanoma. Injection of 2 mL prilocain hydrochloride in 2% epinephrin into the eye muscle cone resulted in improved image quality in seven patients, without side effects. Ocular MR imaging can be indicated to clarify indeterminate sonographic findings in cases of extrascleral growth or to exclude optic nerve invasion in patients with tumors located at the posterior pole of the globe.

Anesthesia, Local↗
PubMed1996

Fast spin-echo MR imaging of the eye.

Magnetic resonance imaging of the eye usually includes T2-weighted images both for screening purposes and for characterization of melanoma. Conventional T2-weighted spin-echo (SE) imaging suffers both from long acquisition times and incomplete recovery of the vitreous' signal. A fast SE sequence was therefore compared prospectively with conventional sequences in 29 consecutive patients with lesions of the eye. Fast SE images delineated melanoma and other lesions of the eye from vitreous better than conventional T2-weighted images. Image quality and lesion conspicuity were improved on the fast sequence. Whereas melanoma appeared hypointense to vitreous on both types of images, subretinal effusion was hypointense on fast images and hyperintense on conventional T2-weighted images. Ghosting of the globe, which, however, did not decrease diagnostic value, was more pronounced on fast images. Conventional T2-weighted images may be replaced by fast SE images in MR studies of the eye with a gain in lesion conspicuity and significant time saving.

Eye Neoplasms↗
PubMed1996

Initial clinical experience with spiral CT and 3D arterial reconstruction in intracranial aneurysms and arteriovenous malformations.

We studied 32 consecutive patients with known or suspected cerebrovascular abnormalities studied with spiral CT following a intravenous bolus injection of iodinated contrast medium with a power injector. Flow was 3 or 4 ml/s. In an attempt to define the appropriate delay time and scan duration a cranial angio-CT without table increment was performed on 10 patients. Enhancement was measured by manually placed regions of interest within the left middle cerebral artery and the inferior sagittal sinus. All patients except one had intraarterial angiography (DSA) for comparison. In 6 patients with an arteriovenous malformation (AVM) follow-up was possible after one and/or two embolisation procedures. These patients had plain and contrast-enhanced spiral CT. The diagnosis was aneurysm in 9 (8 berry aneurysms, one giant fusiform aneurysm), AVM in 13 (all supratentorial) and traumatic arteriovenous fistula in one. In 9 patients there were no detectable pathological vascular findings. After 3D reconstruction the size (between 5 and 28 mm), location and the relationship to the parent vessel of the aneurysms, the extent of the AVMs and the distribution of the embolisation material could be demonstrated clearly. The main feeding vessel(s), nidus and draining veins were reliably shown. The decreased extent of the AVMs after embolisation was clearly demonstrated. There was no difference in diagnosis when DSA and 3D-CT were compared by two independent radiologists. We consider arterial spiral CT with 3D reconstruction to have the potential of offering important diagnostic information for the treatment of intracranial AVMs and aneurysms.

Adult↗
PubMed1996

Calcified brain metastases from ovarian carcinoma.

A case of calcified brain metastases from ovarian carcinoma is reported. Lesions developing during chemotherapy were thought on Ct to be parasitic and, to avoid dissemination of pathogens, biopsy was postponed. When neurological deficits progressed, MRI showed perifocal oedema and contrast enhancement. It also showed a new noncalcified focus which was biopsied, proving to be a metastasis.

Brain Neoplasms↗
PubMed1996

[Duplex sonography in functional thyroid diagnosis].

PURPOSE: Assessment of the functional diagnostic value of Doppler sonographic or sonographic parameters, especially of the peak flow velocity in the inferior thyroid artery in patients with newly manifest autoimmunothyroiditis. MATERIAL AND METHOD: Morphological and Doppler sonographic measurements were done at the inferior thyroid artery on 69 patients suffering from newly manifest Graves' disease or Hashimoto's thyroiditis, as well as on a control group of 18 subjects. The measured data were correlated with thyroid hormone levels and with quantitative scintiscanning. RESULTS: A linear functional correlation was found between the peak flow velocities in the inferior thyroid artery and the fT3 or fT4 level. If the peak flow velocities were greater than 1.2 m/s, hyperthyroid metabolism prevailed, whereas at velocities below 0.3 m/s latent hypothyroidism was present. CONCLUSION: These results show that Doppler sonography of the inferior thyroid artery can supply pointers (capable of being recorded) to the state of functioning of the thyroid even before knowing the laboratory parameters.

Adult↗
PubMed1996

[MRT of the eye: the normal anatomy and detection of the smallest lesions with a high-resolution surface coil].

PURPOSE: A new, high-resolution surface coil for MRI of the eye was evaluated with regard to practicability, image quality and sensitivity for small lesions. MATERIAL AND METHODS: 48 patients in whom a space-occupying lesion of the eye or orbit was suspected were examined (1.5 T tomograph, 5 cm surface coil, T1- and T2-weighted spin-echo sequences, the former before and after i.v. gadolinium DTPA). RESULTS: 45/48 patients tolerated MR with the high-resolution surface coil. No adverse effects were experienced by the patients. In 11/48 patients a space occupying lesion of the eye was detected (melanoma, 5; metastases, 2; haemorrhage, 1; malformation, hamartoma and scarring after melanoma, one each). The smallest detectable lesion had a thickness of < 1 mm. CONCLUSION: First experiences with the high-resolution surface coil indicate that this device is suited for detection of very small lesions of the eye.

Adolescent↗
PubMed1996

[Preoperative staging of bladder carcinomas with Gd-DTPA-supported dynamic magnetic resonance tomography. Comparison with plain and Gd-DTPA-supported spin-echo sequences].

PURPOSE: Evaluation of dynamic Gd-DTPA enhanced MR imaging in the staging of bladder cancer. METHODS: We studied 40 patients with histologically proven bladder cancer. All patients were examined with routine T1- and T2-weighted MRI and late Gd-DTPA enhanced T1-weighted MRI. Additionally, a dynamic study was performed with 10 subsequent short FLASH-2-D gradient echo sequences without delay immediately after bolus injection of Gd-DTPA. Signal intensities of the tumour and of the surrounding tissue as well as image contrast parameters were quantified. RESULTS: The dynamic study showed a higher accuracy in the evaluation of stage pTa to pT2 cancer compared to spin echo MRI (63% and 46%, respectively) and no difference regarding the sensitivity (87.5%). However, overstaging was a problem with both modalities. The contrast-to-noise ratio of bladder tumour and muscle was equal or significant higher with the dynamic study compared to spin echo MRI. A higher signal-to-contrast ratio of bladder tumour and bladder muscle was calculated for the dynamic study compared with the spin-echo MRI (p < 0.01; Mann-Whitney U test). CONCLUSION: Dynamic Gd-DTPA enhanced MRI is recommended to be used additionally in the preoperative staging of bladder neoplasms.

Adult↗
PubMed1996

[Teleradiology: use of multimedia PC for access to electronic patient records and teleconsultation].

A PC-platform is presented using internet technology on Ethernet (local) or ISDN (external) for access to digital hospital infrastructures comprising electronic multimedia patient records integrating information systems of all clinical departments. In addition, a videoconferencing system is implemented for teleconsulting, and a document camera allows transmission of analogue data. In combination with the multimedia-PC. Ethernet as well as ISDN offer satisfying performance for transmission of medical data including images. In 20 cases, visualisation of the electronic patient record, an average CT with report and 58 GIFF Images', or transfer of an ACR-NEMA file from CT, took seconds (Ethernet) or up to 3.5 minutes (ISDN - 58 CT images and report).

Computer Communication Networks↗
PubMed1996

[Can the high-resolution 13-MHz ultrasonography facilitate the preoperative localization and marking of microcalcification clusters?].

PURPOSE: The value of 13 MHz ultrasound regarding the preoperative localisation in combination with mammography were investigated into. MATERIAL AND METHOD: Out of 112 mammaographically detected calcifications, 30 (30 patients) were clusters of microcalcifications. Out of these, 23 were classified as suspicious of malignancy and were preoperatively localised with a 7.5 and 13 MHz probe. Upon marking the skin, a fine needle was inserted, and after due correction blue dye or coal solution was instilled. RESULTS: Following mammographically shown position, 23 clusters of microcalcifications could be localised using the 13 MHz probe. A localisation with the 7.5 MHz probe was impossible in all cases. A single correction of the needle's site was necessary with 35% (8/23) of patients. The maximum distance of the needle's tip in case of misposition measured 11 mm. CONCLUSION: Giving a known mammographic position and a sonographic perceptibility of clusters of microcalcifications in a maximal depth of penetration of 2 cm, 13 MHz high resolution ultrasound examination in combination with mammography prove to be a valuable means in facilitating the preoperative localisation.

Breast Diseases↗
PubMed1996

[Ultrasound examination of the female breast: comparison of 7.5 and 13 MHz].

PURPOSE: We investigated whether the high resolution ultrasound (13 MHz-scanner) shows smaller lesions and better differentiation than the 7.5 MHz-scanner. METHOD: Prospectively, sonography was performed on forty-seven patients with a 7.5 MHz-scanner as well as with a 13 MHz-scanner in identical slices. RESULTS: Obviously we could obtain more exact diagnoses by using the high resolution scanner. In two patients additional satellite of the primary tumor could be found. In four patients, unclear sonographic findings could be identified as cysts. A disadvantage in the usage of the 13 MHz-scanner is that mastopathy and benign lesions are more difficult to diagnose. With the high resolution more details could be seen although the inhomogeneity as well as the irregularity of the margins are seen more clearly and, therefore, the physician has to reestimate his point of view. To optimize the quality of the pictures made by high resolution ultrasound, it is necessary to regulate the system, which sometimes is quite difficult. CONCLUSION: The recognition of smallest lesions and the reliable presentation of cysts indicates that the 13 MHz-scanner is a good additive diagnostic parameter to the 7.5 MHz-scanner. Therefore, this method may become important for diagnosing multicentrity within carcinomas.

Adult↗
PubMed1996

[Differentiation of lacrimal gland tumors with high resolution computerized tomography in comparison with magnetic resonance tomography].

In a retrospective study of 15 patients with epithelial and non-epithelial masses of the lacrimal gland, the value of high-resolution computed tomography (CT) with multiplanar and three-dimensional reconstructions was compared to magnetic resonance imaging (MRI). For the differential diagnosis of lacrimal gland lesions the following parameters are important: shape of the lacrimal gland, internal structure, degree of contrast enhancement and integrity of adjacent bony structures. In evaluation of the extent of lacrimal gland lesions, thin-section CT with multiplanar and three-dimensional reconstruction is equal to MRI, while spiral CT with 1-mm slices is superior to standard CT with 2-mm slices. However, internal structure and contrast enhancement of lacrimal glands, integrity of adjacent bones and intracranial infiltration are better visualized with MRI than with CT. Only inhomogeneous mixed tissue tumors can be differentiated from homogeneous tumors by CT due to density differences. In conclusion, MRI is the method of choice if lacrimal gland tumors are suspected, while CT is only useful in doubtful cases concerning the bony structures as an additional method. Using modern imaging modalities, differentiation between epithelial and non-epithelial masses is possible for further diagnosis and therapeutic decisions. Both pleomorphic adenoma due to its different dense components and malignant masses due to bony destruction and intracranial attachment can be differentiated and treated in a specific way. Differentiation between non-epithelial masses (lymphoma and inflammatory pseudotumor) is only possible with a combination of imaging, clinical appearance and in some cases biopsy.

Adolescent↗
PubMed1996

[Anatomy and pathology of the retrobulbar space in MRI using a high-resolution surface coil].

Because of its high soft tissue resolution and its lack of radiation hazard, MRI is considered a valuable method in the diagnosis of orbital disease. Insufficient spatial resolution was considered the main drawback of orbital MRI. Another problem was the chemical shift artifact caused by shifting of the signal of fat and water. To optimize image quality, a high-resolution coil with a small diameter was constructed. Twenty patients with intraorbital changes were examined with MRI. We used a special surface coil with a diameter of 4 cm. For optimal image quality we modified the bandwidth and other parameters of the sequences. For comparison additional measurements were performed in 13 patients with the standard surface coil (diameter 11 cm) and/or the head coil. The best results were obtained with a middle bandwidth (78 Hz); the chemical shift was reduced significantly. Little motion artifacts are visible in every examination caused by involuntary eye movements, which led to evaluation limitations in 3 cases. Compared to the examination with normal coils, the detection of details was much better. In 3 cases small changes were only found with the high-resolution orbital coil. With the high-resolution surface coil it is possible to examine the orbit. It is like looking through a magnifying glass. Using an optimized bandwidth, both the signal-to-noise and the chemical shift are acceptable. The new orbital coil is especially useful for the detection of small orbital lesions.

Adolescent↗
PubMed1996

[Determining the depth of infiltration in urinary bladder carcinoma with contrast medium enhanced dynamic magnetic resonance tomography. With reference to postoperative findings and inflammation].

OBJECTIVE: The purpose of this study was to evaluate dynamic contrast-enhanced magnetic resonance imaging for the staging of urothelial bladder carcinoma and to compare it with plain and contrast-enhanced spin-echo MRI. METHODS: Pre-operative MRI was carried out in 62 patients. Post-operative histological examination confirmed bladder carcinoma in 50/62 patients. Carcinoma was excluded in 12 patients. Beside spinecho MRI a dynamic contrast-enhanced study was performed immediately after IV application of Gd-DTPA using 10 sequential FLASH-2Dsequences, each with a duration of 15 s. Images were evaluated visually by three radiologists in a blinded fashion. RESULTS: In 41/62 patients pre-operative tumor staging with the dynamic contrast-enhanced study was confirmed by the histological examination after surgery. MRI with spinecho sequences yielded correct staging in 30/62 patients (P = 0.028). Staging of superficial bladder cancer was more accurate with dynamic contrast-enhanced MRI than with conventional MRI (P = 0.024). Overstaging was observed in some patients with stage pT1 tumors. Furthermore, postoperative changes of the bladder wall could be differentiated from cancer due to significantly earlier contrast enhancement of bladder cancer compared with postoperative and inflammatory alterations (P < 0.001). CONCLUSION: Contrast-enhanced dynamic MRI is a helpful addition in the presurgical T-staging of bladder cancer.

Adult↗
PubMed1995

[Quantification of signal modulation of hematopoietic bone marrow in gradient echo sequences. Results of phantom and proband studies with simultaneous determination of T2* relaxation times].

The signals from spongy bone on gradient echo sequences depend on the fat and water proton content as well as the differences in magnetic susceptibility at the border between the trabeculae and the bone marrow. From the signal intensities for different echo times, signal modulation was quantified by a special algorithm and at the same time the T2 relaxation time was calculated. Using a fat-water phantom, it was shown that the product of the initial fat and water signal intensity (modulation coefficient) is applicable to indicate the extent of signal modulation and thereby the chemical shift and, moreover, to indicate changes in the fat/water ratio sensitively. In 16 individuals of different ages (23 to 64 years, average 42.4 years) there was a tendency for the T2 relaxation time from the spongiosa of lumbar vertebrae to increase with age, this can be explained by a reduction in the trabecular content, causing reduction in the magnetic inhomogeneity of the bone marrow. The results indicate the usefulness of the sequence and the mathematical model for evaluating the spongy bone in cases of osteoporosis and of malignant haematological disorders.

Adult↗