Is technetium-99 m-pyrophosphate scintigraphy valuable in the diagnosis of cardiac amyloidosis?

Amyloidosis is a systemic disease frequently involving the myocardium and leading to functional disturbances of the heart. Amyloidosis can mimic other cardiac diseases. A conclusive clinical diagnosis of cardiac involvement can only be made by a combination of different diagnostic methods. In 7 patients with myocardial amyloidosis we used a combined first-pass and static scintigraphy with technetium-99 m-pyrophosphate. There was only insignificant myocardial uptake of the tracer. The first-pass studies however revealed reduced systolic function in 4/7 patients and impaired diastolic function in 6/7 patients. Therefore, although cardiac amyloid could not be demonstrated in the static scintigraphy due to amyloid fibril amount and composition, myocardial functional abnormalities were seen in the first-pass study.

[The clinical relevance of human anti-mouse-antibody (HAMA) in immunoscintigraphy]

Murine monoclonal antibodies (MAb) are applied on a growing scale in radioimmunoscintigraphy (IS) for diagnostic and therapeutic purposes. This increasing use of xenogeneic substances in rapidly growing numbers of patients raises questions of accuracy and reliability of the MAb and also the problem of potential human immunoreaction (human anti-mouse IgG antibodies--HAMA). The aim of this study was to evaluate the clinical relevance of HAMA following IS regarding allergic complications and in vivo effects on IS after repeated applications of MAbs. Out of over 800 immunoscintigraphic examinations performed during the last 5 years in our department 289 studies (in 190 patients) with up to 10 applications (13 different MAbs all together) were considered. Only 1 patient with a high HAMA titer developed a mild allergic reaction (local urticaria) after the 3rd application of an anti-CEA MAb. In 171 intensively documented serum courses following IS, 50 (29%) showed elevated HAMA [1st application: 25/108 (23%); 2nd application: 20/41 (49%): 3rd application: 5/11 (45%); 4th-10th application: no HAMA/11 (2 anti-CEA, 9 Antimyosin)]. Only with strongly increased HAMA values (five times the value before 1st application) there was an altered biodistribution of the MAbs in IS with partially inhibited (8/25 studies with repeated applications) tumor localization. Some patients still demonstrated positive tumor localization despite a HAMA reaction. The problem of HAMA in the diagnostic work-up using MAbs is not the allergic reaction but the potential effects on IS in repeated studies. HAMA should be measured prior to repeated immunoscintigraphic studies.

Immunoscintigraphy using a technetium-99m labelled monoclonal anti-CEA antibody in the follow-up of colorectal cancer and other tumours producing CEA

Using the intact monoclonal IgG1 anti-CEA antibody BW 431/26 (Behringwerke Marburg, FRG) labelled with 99mTc by a new labelling procedure (Schwarz method), 72 patients suspected of tumour recurrences (colorectal cancer, n = 59) and with rising serum carcinoembryonic antigen (CEA) levels were studied. Sixty-nine of 72 studies had a positive result by immunoscintigraphy of which 52 have since been proven histologically/clinically. In six patients only immunoscintigraphy revealed a tumour recurrence while all other diagnostic modalities were negative. Of 52 studies 46 were true positive (diagnostic sensitivity 88%). In this series there was one false positive result. About one-third of all patients injected with the antibody developed a human anti-mouse response (HAMA), but no severe side effects were seen even after four applications. For the follow-up of colorectal and other CEA positive adenocarcinomas this 99mTc-labelled monoclonal antibody seems to be very promising in patients with rising serum CEA, especially if conventional diagnostic imaging procedures remain negative.

Tumour imaging of bladder carcinomas and their metastases with 111indium-labelled monoclonal anti-CEA antibody BW 431/26

Fifty-one patients with muscle-infiltrating bladder carcinoma (T2-T4, N0-3, M0-1) were studied with a new imaging technique using murine monoclonal antibody directed against the carcinoembryonic antigen (CEA). A total number of 67 investigations were performed. The intact 111indium-labelled antibody (BW 431/26, Behringwerke Marburg) detected 86% of primary tumours, 93% of local and 75% of distant metastases whether there was an elevated CEA level in serum or not. Immunohistologically (avidin-biotin-peroxidase method) positive frozen tissue sections from tumour biopsies stained with the same monoclonal anti-CEA antibody, thus confirming the presence of the CEA antigen in vitro. The method was of much higher sensitivity in detecting even very small metastases than X-ray computed tomography (86% versus less than 30%). The specificity was in the region of 90%. The response to chemotherapy (MVEC regimen) was shown by repeated studies demonstrating reduced uptake (partial remission) or no accumulation (complete remission) in the second immunoscan. We suggest immunoscintigraphy of bladder tumours and their metastases as an additional method in preoperative staging and postoperative care.

[In vitro and in vivo effect of thyroid hormones on the growth of neuroblastoma cells. II. The effect of thyroxine in vivo]

We studied the effect of thyroxine (T4 0.050 mg/kg/d, i.p.), TSH (0.08 U/kg/d, i.p.) and hypothalamic peptide (HF; 1 mg protein/kg/d, i.p.) given alone or in combination, on the growth of murine (NB C-1300) and human (NB Park) neuroblastoma transplanted onto the nude mouse (nu/nu). Both T4 and TSH caused a significant increase (perchlorate a decrease) of the serum T3. Histologically, the T4 treatment was followed by partial tumor necrosis and a marked growth of connective tissue within the tumors; there was no significant change in tumor weight as compared to the control group. Treatment with HF alone or in combination with T4 inhibited in 30% the invasive growth of the neuroblastoma transplants and a fatty degeneration was found in 25% of the human NB-TX after 28 days of treatment. The measurement of the intratumoral content of the cyclic nucleotides showed a significant increase of the cAMP and a decrease of the cGMP. The morphological and biochemical alteration observed under treatment with thyroid hormone or analogues could possibly be applied for therapeutic purposes.

[In vitro and in vivo effect of thyroid hormones on the growth of neuroblastoma cells. I. The effect of triiodothyronine in vitro]

The effect of triiodothyronine (T3) on the differentiation of cultured neuroblastoma (NB) cells was studied after 9 days of treatment with a dose of 10(-4) M/10(6) cells per day. Using phase contrast microscopy, 30-50% of NB cells showed formation of neurites as a morphological sign of cellular differentiation. The initial rise of the mitosis rate was followed by a plateau. Changes in cyclic nucleotide content, in the triphosphates and in the activity of the enzyme ornithine decarboxylase (ODC) were assessed in 2 human and 2 murine cell lines to serve as biochemical parameters of the cell differentiation induced by T3. Whereas the cAMP level increased significantly (3 to 7 fold compared with its initial value), the cGMP value dropped to 30 to 50% of that of the control group. ATP and GTP increased about 200%, the ODC showed a decrease of about 50%. The present studies show a biphasic effect of T3 on neuroblastoma cells: the initial rise of mitotic activity is followed by increased cell differentiation starting from day 4 of the treatment.

Multi-centre immunoscintigraphic study using indium-111-labelled CEA-specific and/or 19-9 monoclonal antibody F(ab')2 fragments

Six European nuclear medicine centres performed immunoscintigraphy first retrospectively in 34 patients using indium-111-labelled carcinoembryonic antigen (CEA)-specific and/or 19-9 F(ab')2 fragments. Results for sensitivity and specificity in tumour sites were 94% and 87%, respectively, for the pelvis and 73% and 100% for the extrahepatic abdomen. A second prospective series concerned 58 other patients previously operated on for colorectal adenocarcinoma (27 colon, 31 rectum). Two-thirds of these patients had a suspected recurrence signalled by an isolated rise in tumour markers, and 46 patients examined by immunoscintigraphy, X-ray computed tomography and ultrasonography were found to have a recurrence (a total of 62 tumour sites). Sensitivity and specificity with immunoscintigraphy were 90% and 97%, respectively, for the pelvis and 62% and 95% for the extrahepatic abdomen. For 29 patients injected with CEA-specific fragments, sensitivity was 90% and specificity 94% for the pelvis. For 25 patients injected with 19-9 fragments, pelvic sensitivity and specificity were 80% and 100%, respectively, whereas sensitivity for the extrahepatic abdomen was only 29% since several cases of peritoneal carcinosis were not visualized. In the prospective series, comparison of the three imaging techniques for all tumour sites (including liver and in 5 cases thorax) gave a sensitivity and specificity of 82% and 91%, respectively, for immunoscintigraphy, 52% and 95% for X-ray computed tomography and 59% and 100% for ultrasonography. These results thus confirm the advantage of using 111In-labelled CEA-specific or 19-9 to visualize and localize recurrences of colorectal cancer.

Early immunoscintigraphic localisation of a mediastinal tumour with indium 111-DTPA CEA-specific F(ab')2 monoclonal antibody fragments (BW 431/31) using second tracer isocontour technique

A female patient with steadily increasing carcinoembryonic antigen (CEA) serum levels of unknown origin was referred for immunoscintigraphy with indium 111-labelled CEA-specific monoclonal antibody. The procedure revealed a tumour, undetectable by conventional diagnostic methods. Anatomical landmarking using the second tracer isocontour technique allowed the distinction between an intra- or extrapulmonary lesion. Two months later, tumour infiltration along the aortic arch was confirmed by a targeted angio-CT scan. Upon surgery, the diagnosis was definitely established histologically (undifferentiated, solid large cell carcinoma, most probably arising from the bronchus), and staining by CEA-specific immunohistochemistry confirmed the presence of the CEA antigen.

[Successful immunoscintigraphic tumor detection with technetium 99m marked monoclonal anti-CEA antibodies]

Twenty patients aged 32-76 years (median 56 years) with various primary cancers or tumor recurrences (colorectal n = 14; lung, breast, medullary thyroid carcinoma n = 2, each) were studied with a technetium-99m labeled anti-CEA antibody. Intact monoclonal antibody BW 431/26 (Scintimum CEA-Tc-99m, Behringwerke AG, Marburg) was successfully labeled (Schwarz Method) by an instant 2-vial kit (labeling efficiency greater than 95% (TLC, HPLC), preserved immunoreactivity). The most frequent clinical indications were (1) the detection of tumor recurrences in patients with a steadily increasing serum CEA level (at a mean 2.3 years after complete removal of the primary tumor) but normal findings by conventional imaging modalities, (2) the search for extrahepatic tumor involvement in patients with known liver metastases scheduled for regional chemotherapy. Gamma camera scintigrams (planar and ECT) were performed 6-12 h and 18-26 h postinjection yielding a sensitivity of 95% (positive tumor contrast in 19/20 patients) with a specificity of 90% (positive predictive value 95%). Immunoscintigraphy successfully depicted tumor recurrences in 4/6 patients with elevated serum CEA values where all conventional imaging modalities had failed. The successful labeling of monoclonal antibodies with 99mTc represent an important step in clinical progress for the more practically orientated use of immunoscintigraphy and also opens new diagnostic fields.

A rapid method for the determination of human CEA/mouse anti-CEA immune complexes in patients undergoing immunoscintigraphy

We report here on a new and quick procedure to isolate human (hu) CEA mouse anti CEA immune complexes of sera from patients admitted for immunoscintigraphy with radiolabeled monoclonal anti CEA antibody. This method employs rabbit anti mouse IgG immune affinity chromatography together with a commercial CEA-IRMA kit for the specific isolation of immune complexes. By applying this procedure we were able to show that immune complex formation increased in parallel to CEA serum concentration. The formation of immune complexes did not significantly affect tumor detection by immunoscintigraphy.

99Tcm-labelled anti-CEA monoclonal antibody for tumour immunoscintigraphy: first clinical results

Twenty patients with malignant carcinoembryonic antigen (CEA)-producing tumour recurrences (colorectal n = 14; breast, lung, medullary thyroid carcinoma n = 2, each) were studied by immunoscintigraphy using an intact monoclonal anti-CEA antibody (BW 431/26) labelled with 99Tcm by a new labelling technique (Schwarz Method). This novel approach allows an almost quantitative labelling of the antibody, which is first reduced using a thiol, lyophilized in purified form, and then reacted with a stannous salt component before 99Tcm-pertechnetate binding. The labelling efficiency (as controlled by TLC) was greater than 95%, the in vitro stability at least 6 h. The imaging results (planar and SPECT) yielded a sensitivity of 91%, a specificity of 87% and a diagnostic accuracy of 90%. These first promising clinical results trigger the hope that the successful labelling of monoclonal antibodies with 99Tcm is a decisive step towards the more practically orientated use of tumour immunoscintigraphy.

[Immunoscintigraphy with radionuclide-labeled monoclonal antibodies for tumor diagnosis and in benign diseases]

Immunoscintigraphy using radiolabeled (technetium-99m, indium-111, iodine-131) monoclonal antibodies is successfully (sensitivity over 80%, specificity over 90%) applied since some years in the clinic for the detection of CEA- and or CA 19-9-producing colorectal and CA 125-positive ovarian carcinoma recurrences and just recently for the diagnosis of benign diseases (myocardial infarction/transplant rejection/thrombosis/abscess localization.

[Detection of the binding of 131I-meta-iodobenzylguanidine to structures of the plasma membranes of neuroblastoma cell lines]

In vitro studies of tumor tissue have shown that 131I-IBG is specifically bound to the plasma membrane-enriched fraction of two neuroblastoma cell lines (NA-2 and C-1300). NB C-1300 showed a slightly higher binding capacity than NB NA-2. It may be inferred from experiments performed with activators of the adrenergic and dopaminergic systems that binding of IBG to proteins on the plasma membrane which is physiologically important for binding of this guanidine derivative, is probable.

[Comparison of effort-ECG and radionuclide ventriculography in relation to the detection of myocardial ischemia in isolated stenoses of the anterior interventricular branch]

21 patients with LAD-stenoses of at least 70% and 21 patients with LAD-stenoses and additional intramural anterior wall infarctions were studied. 20 patients without heart disease or after successful transluminal coronary angioplasty and 18 patients with intramural anterior wall infarction after successful transluminal dilatation of the LAD (remaining stenosis maximal 30%) served as controls. The normal range of global and regional left ventricular ejection fraction response to exercise was defined based on the data of 25 further patients without relevant coronary heart disease. Thus, a decrease in global ejection fraction and regional wall motion abnormalities were judged pathological. All patients were comparable with respect to age, ejection fraction at rest and work load. Myocardial ischemia could be detected by the exercise ECG in 81% of all patients without infarction and in 71% of patients with infarction. The corresponding values for global left ventricular ejection fraction were 76% and 81%, respectively, and for regional ejection fraction 95% in both groups. No false-positive exercise ECGs were observed in the healthy controls and 2 (11%) in the corresponding group with intramural infarction. The global ejection fraction was pathological in 1 (5%) healthy subject without infarction and in 3 (17%) corresponding patients with infarction. Sectorial analysis revealed 5 and 22%, respectively. Our findings suggest that the exercise ECG has a limited sensitivity to detect myocardial ischemia in patients with isolated LAD-stenoses and intramural myocardial infarction. Radionuclide ventriculography yields pathological values more often; however, false-positive results also occur more frequently.

[Immunoscintigraphy using 111In-DTPA-labeled monoclonal antibodies: comparison with ECT and planar scintigraphy]

The present study was done in order to examine if the use of 111In-DTPA-labeled MAb fragments in place of 131I-labeled MAb fragments increases the sensitivity of tomographic immunoscintigraphy to reach the level of that of planar imaging techniques. In 11 patients with various primary tumors, local recurrences or metastases [colorectal carcinoma (n = 7), ovarian carcinoma (n = 2), papillary thyroid carcinoma (n = 1), undifferentiated carcinoma of the lung (n = 1)], immunoscintigraphy (IS) was carried out using 111In-DTPA-labeled F(ab')2 fragments of various MAbs (anti-CEA, OC 125, anti-hTG) and planar and tomographic imaging were compared intra-individually. By conventional diagnostic procedures, the presence of a tumor mass was confirmed (transmission computer tomography, ultrasound) or verified (131I whole-body scintigraphy, histology) in all cases. Immunoscintigraphy was positive in 9 out of 11 cases by ECT and in 10 out of 11 cases by planar imaging. When using 111In-labeled MAb fragments, intra-individual comparison of ECT and planar imaging resulted in a similar sensitivity. The increased sensitivity of ECT using this tracer in contrast to 131I-labeled MAb fragments may be attributed to the fact that the physical properties of 111In are much more suitable for the gamma cameras most commonly used (single detector, 3/8'' crystal); using 111In-labeled MAb fragments, count rates sufficient for ECT can be obtained within a reasonable acquisition time. This allows to combine IS with the advantages of ECT regarding tumour localization and prevention of artefacts due to superposition of background.

131-Metaiodobenzylguanedine therapy of neuroblastoma in childhood. One year of therapeutic experience

Eleven children with neuroblastoma refractory to conventional therapy or relapse of neuroblastoma were treated with 131-metaiodobenzylguanedine (MIBG). The therapeutic results and the side effects were evaluated. In one patient with disseminated bone marrow involvement complete remission was obtained. Partial remission was observed in six patients and stable disease in another. Three patients did not respond to MIBG, in two of them the tumours did not accumulate a sufficient MIBG dose. Clinical and laboratory examinations revealed an excellent tolerance of MIBG in all patients. First attempts to continue cytostasis after MIBG therapy were made. MIBG has a good therapeutic efficacy is sufficiently incorporated into the tumour cell.