Estimation of the wear volume after total hip replacement. A simple access to geometrical concepts.

Various formulas have been proposed to calculate the volume of prosthetic wear from the penetration depth of the head as assessed on plain radiographs, based on idealized, three-dimensional geometrical models of a prosthetic hip. However, for most published formulas no (or no simple) derivation is available and not all of them are correct. We describe a simple geometrical model that allows for transparent derivation of equations for various components of prosthetic wear volume and compare the calculated volumes with those obtained from published equations. These components are: (1) a right generalized cylinder resulting from a linear shift of a half spherical part of the prosthetic head into the hemispherical cup, (2) an additional wedge that is "cut" from the cup and (3) the wear from an optional additional cylindrical portion of the cup. We emphasize that calculation of a three-dimensional wear volume from linear penetration depth should be based on a geometrical concept that is transparent and simple enough for clinical research, such as the one presented. The incorrect formula of Kabo et al. should be completely abandoned.

Noninvasive procedures for diagnosis of renovascular hypertension in renal transplant recipients--a prospective analysis.

The purpose of this study was to clarify the selectivity and specificity of noninvasive procedures for diagnosis of clinically suspected posttransplant renovascular hypertension. We prospectively investigated 25 renal transplant recipients with arterial hypertension and clinically suspected stenosis of the graft artery (8 female and 17 male patients; ages 45 +/- 15 years). We performed a captopril test with 25 mg captopril (n = 25), renography with technetium-99m diethylene triamine penta-acetic acid (99mTc-DTPA) before and after angiotensin-converting enzyme (ACE) inhibition with determination of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) (n = 23) and color-coded duplex ultrasonography of the transplant kidney vessels (n = 24). Renal transplant artery stenosis (RTAS) was excluded by renal arteriography in 20 patients and by operative evaluation or clinical follow-up in 5 patients. We identified 4 patients with RTAS and renovascular hypertension. The noninvasive methods showed the following results (sensitivity/specificity): (1) captopril test: 75%/67%; (2) renography combined with ACE-inhibition: 75%/84%; and (3) color-coded duplex ultrasonography: 100%/75%. We conclude that in patients with clinical evidence of RTAS most noninvasive diagnostic procedures are not sufficiently accurate to exclude the diagnosis. Only color-coded duplex ultrasonography did not fail to detect all patients with RTAS and may act as a screening test. Intraarterial renal angiography remains the most reliable and as-yet indispensable diagnostic test for transplant recipients to rule out RTAS.

Detection of infection in postoperative orthopedic patients with technetium-99m-labeled monoclonal antibodies against granulocytes.

A prospective study of 106 orthopedic patients was performed for the detection of infection in the early postoperative stage using 99mTc-labeled murine Mabs directed against epitopes on granulocytes. Accuracy was 81% in the hips (n = 26), 81% in the thigh (n = 21), 84% in the knee (n = 19), and 100% in the tibia (n = 27). The technique did not work well in the spine where false-negative results were observed in the three patients studied. One patient suffered transient swelling of the eyelids following injection. Optimal imaging results were obtained 2-6 hr postinjection.

Fluorine-18-FDG and iodine-131-iodide uptake in thyroid cancer.

UNLABELLED: We conducted a prospective study to define the sensitivity of 131I scintigraphy and 18FDG PET whole-body scanning in the detection of thyroid cancer and metastases. METHODS: Forty-one patients with differentiated thyroid carcinoma who underwent thyroidectomy and 131I elimination of the remaining thyroid were studied by 18FDG whole-body PET in 52 examinations and by 131I whole-body scanning. RESULTS: Combined 18FDG and 131I imaging resulted in a sensitivity of about 95%, with alternating uptake of 131I and 18FDG in the metastases: 131I trapping metastases with no 18FDG uptake and 18FDG trapping metastases with no 131I uptake. Five uptake types were differentiated. Alternating uptake was found in about 90% of the patients, which was nearly identical to the sensitivity of the combined 131I/18FDG investigation. In six patients with increasing human thyroglobulin levels, we found that 18FDG whole-body PET localized positive neck metastases of papillary thyroid carcinomas that were histologically confirmed after extirpation. CONCLUSION: Combination 18FDG and 131I whole-body imaging protocol enables detection of local recurrence or metastases on whole-body scans that are often not shown by other imaging methods. Biochemical grading of thyroid cancer may also be possible with this method: Tumors with remaining functional differentiation for hormone synthesis and iodine uptake have low glucose metabolism in more than 95%; tumors without this functional differentiation of 131I uptake show high, glucose metabolism. Fluorine-18-FDG uptake seems to be an indicator of poor functional differentiation, and possibly higher malignancy, in thyroid cancer.

Catecholamine secreting glomus tumor detected by iodine-123-MIBG scintigraphy.

We report the case of a 41-yr-old woman who presented with arterial hypertension and tinnitus in the right ear synchronous with pulse. She had previously undergone surgery for suspected pheochromocytoma without positive therapeutic effect. CT and MRI revealed a homogenous tumor with contrast enhancement in the right hypotympanon and foramen jugulare, and [123I]metaiodobenzylguanidine (MIBG) scintigraphy demonstrated strong tracer uptake in the same area. Selective venous sampling of catecholamines in the ipsilateral jugular vein confirmed the tumor to have originated from hormone production.

Accurate local blood flow measurements with dynamic PET: fast determination of input function delay and dispersion by multilinear minimization.

Accurate determination of local blood flow in tissue using the Kety-Schmidt one-compartment model for freely diffusible tracers requires knowledge of the true arterial input function in tissue. Because measured input functions are usually delayed and dispersed with respect to true influx, a correction of the experimental input function is necessary. We describe a technique that uses a fast multilinear least-squares minimization procedure to determine simultaneously the dispersion, the blood flow and the partition coefficient as a function of delay. In this approach, a few multilinear fits are sufficient to determine the complete set of parameters necessary to describe the data. Because of the high speed of the procedure, dispersion effects may be taken into account on a pixel-by-pixel basis in calculating parametric images of blood flow and partition coefficient. The described procedure has been used at our institute for about 1 yr in more than 160 investigations and has proven well suited for routine use in a clinical environment.

Radiation-induced heart disease: morphology, changes in catecholamine synthesis and content, beta-adrenoceptor density, and hemodynamic function in an experimental model.

To study further the pathophysiology of radiation-induced cardiomyopathy, we investigated resting hemodynamics, myocardial catecholamine synthesis and storage, and beta-adrenoceptor density after local heart irradiation. In Wistar rats, a radiation dose of 20 Gy eventually leads to compromised myocardial function which is characterized by a reduction in cardiac output to 43 +/- 11% and in the left ventricular ejection fraction to 66 +/- 7.5%, and an increase in the left ventricular end-diastolic volume to 187 +/- 17% of control values. This reduction in function is correlated with focal degeneration of 23 +/- 4% of the myocardium. Measurement of tyrosine hydroxylase activity and catecholamine content revealed that catecholamine biosynthesis is unchanged in the adrenals but is significantly reduced in the hearts of irradiated animals, while cardiac beta-adrenoceptor density is increased to about 140% of that in age-matched controls. This is in contrast to findings in dilated or ischemic cardiomyopathy. Time-course studies showed that the development of myocardial degeneration starts simultaneously with the decrease in cardiac output and ejection fraction and the increase in beta-adrenoceptors at 50-80 days postirradiation. Myocardial degeneration is maximal in extent and severity at 100 days and does not progress thereafter. Cardiac output decreases at 80-100 days postirradiation to 60 +/- 7% of control values. A significant further decrease is seen only when congestive heart failure becomes manifest at 249 +/- 21 days after 20 Gy. Thus there is a delay between structural myocardial injury and hemodynamic deterioration which could be due to a compensatory increase in beta-adrenoceptor density during the initial stages of the cardiomyopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical importance of emission-computed tomography of the skull in bone scintigraphy]. / Klinische Bedeutung der Schädel-Emissionscomputertomographie in der Knochenszintigraphie.

Sixty-five ECT examinations were carried out in patients with abnormalities of the skull base and paranasal sinuses and the results were compared with ordinary scintigraphy and CT. ECT provides additional information as compared with scintigraphy by its images in three planes, which are free of superimposition. This is of value in the localisation of the lesion and for determining its extent and activity. It is a functional tomographic method which is complementary to the morphological information provided by CT. The indications and value of the method in inflammatory, metastatic and neoplastic diseases are discussed.

[Radiological investigation of the bile ducts following cholecystectomy. Paper III: Determination of the diameter of the common bile duct by isotope methods (author's transl)]. / Radiologische Gallenwegsdiagnostik nach Cholezystektomie. III. Mitteilung: Die nuklearmedizinische Weitenbestimmung des Hauptgallenganges.

The diameter of the common bile duct can be determined by means of quantitative hepato-biliary functional scintigraphy to an accuracy of +/- 2 mm. It is necessary to keep the conditions of the test constant, such as constant regions of interest and size of region. A common bile duct diameter greater than 10 mm. is suggestive of biliary obstruction, diameters above 15 mm. are definite proof. For the demonstration of post-hepatic obstruction, the hilar flow curve is confirmatory. Peristalsis of the common bile duct, which is an unlikely phenomenon in view of the anatomic studies of the muscle in the bile duct, cannot be demonstrated in this way.

[Angiodynography of circumscribed thyroid changes]. / Angiodynographie bei umschriebenen Schilddrüsen-veränderungen.

Conventional methods of thyroid diagnosis, such as scintigraphy, differentiate between hot and cold areas, but within cold areas no distinction between malignant and benign changes is possible. Angiodynography provides a new method which gives the usual sonographic information and also indicated variations in blood-flow in the organ. Various diagnostic methods--thyroid scintigraphy, conventional sonography, fine-needle biopsy and angiodynography--have been compared in patients with focal thyroid disease. It has been shown that it is possible to differentiate between malignant and benign lesions on the basis of their vascularisation.

[First clinical experience with axial emission computer tomography (author's transl)]. / Erste klinische Erfahrungen mit einem axialen Emissions-Computer-Tomographen.

104 examinations were carried out on 81 patients with a new commercial emission computer tomographic scanner. The technique provides additional information in half the brain scans, but only in one third of liver scans. No indications for this examination could be discovered in a relatively small clinical material for the examination of the kidneys or the skeleton. Other organs were not included in this assessment. The authors confirm reports in the literature which show that this method is not particularly valuable for finding pathology. It finds its application in conforming or excluding suspected abnormalities and for better localisation and delineation of lesions, thereby aiding differential diagnosis. However, further technical improvements and increased clinical experiency may increase the applicability of the technique.

[Determination of the arterio-portal blood flow relations of the liver--results using 99mTc-hepatobida and a review of methods]. / Die Bestimmung des arterio-portalen Durchblutungs-verhältnisses der Leber--Ergebnisse mit 99mTc-Hepatobida und Methoden-Ubersicht.

The arterial-to-portalvenous blood flow ratio (APV) has been determined routinely within liver bile studies carried out with 99mTc-hepatobida. Out of 1300 patients studied since 1978, 80 were analysed in detail concerning the fixed time parameters to separate the arterial and the portalvenous phase. The arterial phase was assumed to end 4 s after the first aortal peak, immediately followed by a portalvenous phase of 12 s duration. The "triangular area approach" of Biersack (1977) and George (1974) developed for pertechnetate and colloid, was directly applied to hepatobida. The fixed phase limits of hepatic circulation described above were compared to circulation parameters obtained from the beginning of the right ventricular recirculation and from the first decline of the spleen curve (for the end of the arterial phase), and from the second left ventricular peak (for the end of the portal phase). Our 4 s of aortal to end-arterial time agreed excellently with a corresponding control value of 4.1 s, as did the duration of the portal phase with 12 s compared to a control value of 12.1 s. An upper normal value of 45% APV was established, based upon sensitivity, specificity and a classification of hepatic curves. The "triangular area approach" appears at first to be inconsistent from a methodological point of view. We present a critical typology of assessing the APV. Basically we distinguish between strictly intravasal and all other types of tracer. The former are studied adequately by deconvolution and subsequent "real" area approaches, reflecting the full tracer passage through the liver. All not strictly intravasal tracers (pertechnetate, colloid, hepatobida) are subjected to a model assumption of a pure uptake without relevant tracer elimination during the first pass. We conclude that the Biersack-George method may be regarded as a heuristic correction of an amplitude approach within our typology, and that our fixed phase limits are justified by circulation analysis.

[Thyroid scintigraphy with Fresnel zone plates]. / Schilddrüsenszintigraphie mit Fresnel-Zonenplatten.

Coded apertures supply a decoupling of resolution and sensitivity in scintigraphic imaging. The reconstructed images are focussed on different planes. The approach presented replaces the conventional collimator by three Fresnel zone plates in order to simulate a complex projection. The theoretical advantages of scintigraphy with coded apertures could be demonstrated in thyroid imaging. Unresolved artifacts and the lack of availability impair its routine use.

[Planar imaging of emission-computed tomograms of the left ventricular myocardium using 201T1 chloride]. / Flächendarstellung von Emissionscomputertomogrammen des linksventrikulären Myokards mit 201T1-Chlorid.

A new method of processing SPECT of 201T1 myocardial images is demonstrated based on the idea that 3-dimensional myocardium might be a curved area which can be presented in an unfolded form as a single planar image. An example of the procedure including parametric pictures is demonstrated.

[Checklist for understanding magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS)]. / Checkliste zum Verständnis von Magnetresonanz-Imaging (MRI) und Magnetresonanz-Spektroskopie (MRS).

Overview on informations which are necessary to interpret MRI and MRS. The approach is related rather to application than it is a physical one. The central steps in comprehending MR are presented, e.g. frequency decomposition in order to obtain local information with MRI or chemical information with MRS, the spin echo in order to differentiate instrumental dephasation from dephasation by molecular interference, perfusion in MRI, and the components of sensitivity in measuring different nuclei etc. The report terminology is based on the description of grey scale pictures, but one has to consider that the information is not one-dimensional but multiparametric. Therefore new terms have to be developed, a problem similar to that of describing scintigraphic time sequences in nuclear medicine.

[Comparative diagnosis of focal liver changes using computed tomographic and scintigraphic methods]. / Vergleichende Diagnostik fokaler Leberveränderungen mittels Computer-Tomographie und szintigraphischer Methoden.

The value of scintigraphic methods for the diagnosis of focal lesions of the liver (IDA, colloids, blood pool) in comparison to dynamic sequential computer tomography (CT) has been examined in this study. We found CT to be diagnostic in typical cases. For example, focal nodular hyperplasia is characterized by a rapid, strong increase and subsequent decrease after application of contrast medium (71%), whereas hemangiomas show a delayed density increase mostly at the rim (20%). In the event of deviations from the typical pattern, scintigraphic methods have to be applied which then often yield a specific diagnosis, especially in hemangiomas, focal nodular hyperplasia, and adenomas (71%). Ultrasound findings indicating the possible presence of hemangiomas or focal nodular hyperplasia should lead to scintigraphic studies prior to CT, not only for reasons of economy.

[Comparison of the clinical value of an iterative reconstruction procedure with that of a filtered back projection in SPECT of the liver]. / Vergleich der klinischen Wertigkeit eines iterativen Rekonstruktionsverfahrens mit der gefilterten Rück-projektion bei der SPECT der Leber.

We have tested an iterative reconstruction procedure against the usual filtered back-projection in 14 patients with SPECT-examinations of various liver diseases. The aim of the examinations was to assess the presence of liver tumors in most cases. Further indications were Budd-Chiari syndromes and a liver malconfiguration in one case. Three of six haemangiomas and both liver metastases were better delineated with the iterative method, in one patient the haemangioma was visible only with this method. An irregular pattern after filtered back-projection led to misinterpretation as multiple metastases in another patient in whom there was no irregularity after iteration. Diagnostic improvement was not reached in the Budd-Chiari syndromes or in an atypical liver configuration, with a more homogeneous pattern after iteration however. The iterative reconstruction procedure was superior to the filtered back-projection method in the detection of small focal liver diseases.

[180 degree versus 360 degree rotation in SPECT of bone]. / 180 Grad- versus 360 Grad-Rotation bei der SPECT des Skeletts.

Opinions differ as to the advantages of the 180 degrees and the 360 degrees techniques concerning myocardial scintigraphy with 201Tl. Following our own encouraging experiences with the 180 degrees technique, we have looked for cases in bone scintigraphy where reconstructions from a semicircle could be advantageous over a full circle reconstruction. There were metastases and foci of osteomyelitis in spine, ribs and skull (especially in the skull base), to be seen better in reconstructions using images out of 180 degrees close to the object. In knee SPECT a closer radius of rotation can be chosen with single-head cameras so that, when using the 180 degrees technique, a better reproduction of the anatomical structures and pathological alterations is achieved.

Myocardial perfusion and left ventricular function early after successful PTCA in 1-vessel coronary artery disease.

Myocardial perfusion (201TI-ECT) and contractile function (99mTc-ventriculography) were studied during exercise and rest 3 to 6 days after PTCA in 20 patients (11 with stable and 9 with unstable angina pectoris). All patients had single vessel disease and no previous myocardial infarction. During exercise after PTCA the ejection fraction increased for 3 to 5% and no regional wall motion abnormalities, ST-segment depression or perfusion defects occurred (with exception in one patient with very early restenosis). Therefore, perfusion and wall motion were completely normalized at rest and during exercise within days after technically successful PTCA even in patients with previously unstable angina pectoris. Pathological stress test results after this time should thus be attributed to other causes e.g. early restenosis, multivessel disease, false positive tests) and are not due to the specific situation early after PTCA.

[18FDG whole-body PET in differentiated thyroid carcinoma. Flipflop in uptake patterns of 18FDG and 131I]. / 18FDG-Ganzkörper-PET bei differenzierten Schilddrüsenkarzinomen. Flipflop im Speichermuster von 18FDG und 131J.

In 27 examinations of 24 patients with differentiated thyroid carcinoma an alternating pattern of metastases with either 131I- or FDG-uptake was found. In the follow-up of these patients this flip-flop pattern was seen in 89% (17/19) of patients with metastases and uptake of 131I or FDG as described here as uptake types 1 and 2 (type 1: FDG-positive and 131I-negative; type 2: FDG-negative and 131I-positive). In 4 patients a mixed type was observed (uptake type 3), i.e. a combination of metastases with uptake types 1 and 2 in the same patient. Metastases of papillary or follicular thyroid carcinoma without uptake of iodine have all been found to be FDG-positive in patients with an increase of thyroglobulin and with negative diagnostic results from other imaging modalities, and were histologically confirmed by surgery. False-negative or false-positive cases were not observed in this study. The FDG uptake showed an inverse proportionality to iodine uptake and to tumor differentiation. Increased glucose metabolism is a sign of higher malignancy.