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Biomedical subjects

H Bihl

Publications and source records attributed to H Bihl.

At least 19 recordsLinked to original sources
PubMed1992

Late cervical lymph node recurrence in differentiated thyroid carcinoma. An inherent problem of 131I beta dose distribution in small tumor deposits?

In differentiated thyroid carcinoma, postoperative radioiodine therapy is an undisputed element of the integral therapeutic concept. Sometimes, however, and years after initial diagnosis and therapy, cervical lymph node metastases occur without any evidence of local relapse or distant metastases, indicating that radioiodine therapy has not achieved definite tumor cell sterilization. A Monte Carlo computer simulation of the spatial energy dose distribution of 131I in small functioning tumor manifestations was performed to explain this phenomenon. It appeared that only a small fraction of the total beta-energy dose can be deposited inside the tumor if the latter becomes smaller than 1 mm in diameter: for tumors with homogeneous 131I uptake and diameters of 1.0, 0.5, 0.2, 0.1, 0.05 and 0.02 mm, this value does not exceed 86, 73, 39, 16, 8 and 4%, respectively. These data suggest a potential therapeutic gap for small tumor manifestations not apparent at the time of initial diagnosis and could explain the occasional occurrence of late cervical lymph node metastases.

Combined Modality Therapy↗
PubMed1991

Non-invasive detection of reduced regional myocardial perfusion at rest in patients with unstable angina pectoris: increased regional 81mKr deposition following intravenous injection of 81Rb.

The present study was to investigate whether combined imaging of 81Rb and 81mKr distributions after i.v. injection of 81Rb at rest might improve the differentiation between ischemic and irreversibly damaged myocardium as compared to 201Tl scintigraphy at rest. In 21 patients who had undergone diagnostic cardiac catheterization for evaluation of chest pain, 148 MBq ultrapure 81Rb were injected i.v. at rest immediately following 201Tl scintigraphy at rest. Of 14 patients with earlier myocardial infarction, 10 patients revealed decreased regional tracer uptake of 81Rb and/or 81mKr, compared to 12 patients with regional 201Tl uptake abnormalities. In 3 patients with unstable angina pectoris, however, an evident mismatch between either the regional 201Tl or 81Rb distributions and the distribution of 81mKr was observed: in contrast to the reduced uptake of 201Tl and/or 81Rb, 81mKr activity was increased in 3 myocardial segments with normal left ventricular performance but supplied by coronary arteries with high-grade stenoses. In patients with contraindications to exercise tests (e.g. unstable angina) 81Rb/81mKr rest scintigraphy may therefore assist the differentiation between malperfused but potentially viable and irreversibly damaged myocardium.

Angina, Unstable↗
PubMed1991

[Postoperative external radiotherapy of differentiated thyroid carcinoma: when is radioiodine therapy alone inadequate? The dosimetric considerations with a Monte Carlo simulation].

Indication for postoperative external radiation of differentiated thyroid cancer has remained an issue of controversial discussion and is generally restricted to those cases where local tumor control by I-131 therapy alone seems doubtful. This may be the case when lymph node metastases are present or occult micrometastasis are suspected, as the beta(-)-radiation caused by the incorporated I-131 may be deposited partly outside the tumor. This problem of dose distribution is analysed in a simulation model by Monte Carlo techniques where tumors are tissue equivalent spheres of various size (r = 20 microns to 2 cm). Homogeneous I-131 distribution in the whole tumor volume (a) is analysed as well as peripheral deposition confined to the tumour surface (b). In tumors of r = 0.5 mm or less, the percentage of the total dose deposited inside the tumor rapidly decreases, r = 20 microns: 4.1% (a) and 0.9% (b), respectively. Furthermore, extensive dose inhomogeneities appear in tumors of similar sizes. As in local lymph node metastases tumoricidal radiation doses are not necessarily achievable by I-131 therapy alone, postoperative external radiation should be taken into account in the above mentioned clinical situations.

Combined Modality Therapy↗
PubMed1991

[The place of 99mTc-MDP skeletal scintigraphy in neuroblastoma. Is a new assessment necessary?].

The present study compares the reliability of MIBG and MDP bone scans in detecting bone metastases of neuroblastoma. Out of 57 patients, 23 had both 99mTc-MDP and 123I/131I-MIBG scans within a 2-week period. In 10 patients at primary diagnosis there was an underestimation of skeletal involvement by MIBG in 1/5, in 13 patients at follow-up in 3/9; 99mTc-MDP scans were able to visualize skeletal involvement in all those cases. There was only one false positive MDP scan. These results suggest that MIBG alone may fail to visualize skeletal involvement of neuroblastoma and should therefore be complemented by additional 99mTc-MDP scintigraphy.

3-Iodobenzylguanidine↗
PubMed1990

Antibody accumulation in small tissue samples: assessment by quantitative autoradiography.

Uptake of radiolabeled 125I monoclonal antibodies in small metastases can only be characterized by autoradiographic techniques. To obtain quantitative data out of autoradiographic images, a transformation of the essentially two-dimensional signal into the Bq per unit volume information is needed. Part of the calibration problem could be solved by using tissue-equivalent standard preparations. However, when aiming at a quantification of radioactivity in small areas (less than or equal to 2 mm diameter), special criteria had to be expanded upon for the reconstruction of the area in the dose matrix and for the correct integration of the radioactivity content.

Animals↗
PubMed1990

Antibody transport and internalization into tumours.

Internalization of monoclonal antibody (MAb) conjugates is an important feature of tumour targeting, both with respect to the therapeutic action of substances coupled to the antibody and to retention of radionuclides. Problems of analysing internalization in vitro and in vivo, of manipulating internalization, and of evaluating the involvement of normal tissues are illustrated by recent experimental data and are discussed in the light of published evidence.

Animals↗
PubMed1990

Quantitation of antibody uptake in spontaneous metastases.

A procedure of high resolution quantitative autoradiography was established and tested in the murine ESb-Mp lymphoma system. Using 125I-labelled antibody 12-15A, liver metastases with diameters down to 100 microns were identified and intralesional radioiodine accumulation was assessed as % injected dose (iD) g-1. Uptake was found to be highest in intermediate size metastases, i.e., up to 100% iD g-1 in 1 mm lesions, while it gradually declined with both increasing and decreasing diameters of metastases. Lower uptake in large size metastases was due to a marked non-uniformity in radioactivity retention, while lower uptake in small metastases was possibly due to insufficient access of the antibody to intrahepatic processes which have not yet established an autonomous blood supply.

Animals↗
PubMed1989

[Bone marrow changes in Hodgkin's disease: MR tomography and chemical shift imaging].

A patient with Hodgkin's disease, who had received various forms of treatment, was examined by MR tomography and scintigraphy; the results are discussed together with the findings of the bone marrow biopsy. A spectroscopic imaging technique (modified Dixon method) and quantitative evaluation of the fat and water components of the RF signal provide new diagnostic information that may improve the differential diagnosis. Serial examinations following supra-lethal therapy and bone marrow transplantation have been able to show changes in the bone marrow and these could be evaluated quantitatively.

Adult↗
PubMed1988

Extrarenal abnormalities in Tc-99m DTPA renal perfusion studies due to hypervascularized tumors.

In cases of impaired renal perfusion and/or function, Tc-99m DTPA renal flow studies are often used as screening procedures. Besides the demonstration of pathological changes in renal perfusion and/or function, various extrarenal abnormalities may sometimes be detected. Three cases of hypervascular tumors were detected during the course of Tc-99m DTPA renography. These findings stimulated further diagnostic clarification revealing extended extrarenal lesions associated with several different etiologies: angiomyolipoma in tuberous sclerosis, extramedullary manifestations of plasma-cytoma, and metastasis of renal carcinoma. One should be aware of these extrarenal abnormalities in renal flow studies since these three tumor entities frequently exhibit increased vascularity.

Adolescent↗
PubMed1988

[Clinical picture and possible causes of functional disorders of the parotid gland in radioiodine therapy of differentiated thyroid cancer].

The parotid gland function was examined in 31 patients with thyroid carcinoma treated with radio-iodine. Beside enhanced values of sodium concentration, protein concentration and alpha-amylase activity following each therapy, a continuous reduction of flow rate and alpha-amylase activity is found according to the cumulative total dose. The importance of glandular kallikrein und phosphohexoseisomerase (PHI) are discussed with regard to their possible role in glandular damage. A comparison is made with chronic recurrent parotitis, and therapeutical aspects are considered. On the whole the present investigation shows that radio-iodine therapy causes damage to the parotid gland, which normally leads to measurable effects after cumulative doses of 470 mCi.

Combined Modality Therapy↗
PubMed1987

[False-positive findings of 67-gallium scintigraphy in staging/restaging of malignant lymphoma].

Gallium scintigraphy has been an established method for the diagnosis of malignant lymphomas for some years. If properly interpreted, the value of the method is not necessarily reduced by the lack of tumour specificity and the well known property of 67Ga to accumulate in inflammatory and granulomatous conditions. A retrospective analysis of 123 patients with malignant lymphomas showed false positive 67Ga scintigrams in 7%. These cases demonstrate the spectrum of possible errors. 'False positives' were all those localised areas of uptake which were due to some pathological condition which was not lymphomatous. All the positive gallium findings could be elucidated by clinical, radiological and histological investigations.

False Positive Reactions↗
PubMed1987

[Uptake behavior of bone metastases of hypernephroma in the 99m Tc-MDP bone scintigram. A comparison with x-ray findings].

Ninety-one radiologically confirmed osteolytic metastases in 30 patients with hypernephromas were studied with regard to their uptake of 99mTc-MDP and this was compared with the radiological findings. In 16% of the radiologically proven metastases, there was no correlation with their isotope uptake. Compared with other bone metastases whose isotope uptake has been studied and described in the literature, there appears to be a higher proportion of hypernephroma secondaries that do not show uptake of 99mTc-MDP.

Adult↗
PubMed1987

[Value of various radiological study results in the follow-up of Camurati-Engelmann disease].

Camurati-Engelmann disease is a rare progressive bone dysplasia; involvement of the skull base can lead to deafness, vestibular disturbances, facial paralysis and damage to the optic nerves. Treatment with corticosteroids, calcitonin and diphosphonates promises only very limited success. Conservative treatment of compression of the cranial nerves is almost ineffective, but the aim of surgical treatment is decompression of involved nerves. The differential diagnosis depends on radiological findings and clinical symptoms. Follow-up depends on radiographic examination and skeletal scintigraphy for showing the extent of the disease. CT may help in demonstrating compression of cranial nerves and define the indications for surgical decompression.

Adult↗
PubMed1987

Unilateral gallium-67 uptake in primary tuberculosis of the major salivary glands.

Unilateral radionuclide accumulation in salivary glands is an uncommon finding on gallium scintigraphy. The differential diagnosis includes malignant tumors and inflammatory processes of these organs. Two cases of unilateral gallium uptake of the parotid and submandibular gland respectively, verified as solitary tuberculosis, are presented, together with the correlative findings of Tc-99m pertechnetate scintigraphy, sialography, and sonography. None of these imaging modalities is specific enough to provide pathognomonic signs for tuberculosis. When assessing unilateral gallium uptake of the salivary glands, one should be aware of the possibility of tuberculosis.

Adult↗
PubMed1987

[Value of leukocyte and gallium scintigraphy in the differential diagnosis of splenic abscess/-infarct].

The authors describe the limited role of non-invasive imaging procedures in the differential diagnosis of splenic abscess versus infarction. Sonography and computed tomography often do not offer any characteristic findings in these splenic disorders. A case is reported as an example. By means of 111 In-labelled leukocyte and gallium-67-scintigraphy exclusion of acute inflammatory processes can be performed with great certainty, and unnecessary surgical interventions can thus be avoided.

Abscess↗