Automated comparison of scintigraphic images.

New algorithms for automated comparison of scintigraphic images have been developed and are described here. The first step presented here is the registration of the images, performed by optimizing, with respect to the registration parameters (two translational shifts, one angle of rotation, the two parameters of a linear transformation of the gray levels), the stochastic sign change (SSC) criterion. The optimization of this criterion is demonstrated to be efficiently performed using the adaptative random search strategy; a more limited but less time-consuming method is also presented. The second step described is the point-by-point comparison of the registered images. The pixel-by-pixel application of Poisson variable statistical tests permits the generation of the significant image differences. From such images it is possible to detect modifications which escape visual inspection. Examples of applications are given in controlled and routine conditions. These algorithms are useful for the processing of many investigations and are proposed for implementation on all nuclear medicine data processing systems.

Metastatic calcification in the thyroid gland demonstrated on bone scan in a patient with primary hyperparathyroidism.

Bone scanning agents are known to accumulate in extraskeletal sites. We report the case of a patient with primary hyperparathyroidism whose bone scan performed with [99mTc]HMDP revealed not only the classic pattern described in hyperparathyroidism, but also a striking visceral uptake in the lungs, heart, stomach, and thyroid gland. Metastatic calcification was found on histologic examination of the thyroid.

Thoracic and abdominal SPECT-CT image fusion without external markers in endocrine carcinomas. The Group of Thyroid Tumoral Pathology of Champagne-Ardenne.

UNLABELLED: Superimposition of SPECT and computed tomography (CT) slices from the thoracoabdominal region was achieved without the use of external markers for 14 studies in 13 patients with endocrine carcinoma. Technical feasibility and clinical validation of this retrospective fusion method were assessed. METHODS: Patients had a history of thyroid cancer or of carcinoid tumor. To detect tumor sites, CT scan and dual-isotope tomoscintigraphy were performed, with 99mTc-hydroxymethylene diphosphonate for bone scintigraphy and with 111In-pentetreotide, 131I or 131I-metaiodobenzylguanidine for tumor scintigraphy (TS). A superimposition method previously developed for the pelvic region was adapted to the nonrigid thoraco-abdominal region. CT-bone scintigraphy and CT-TS superimposed images were obtained. Clinical validation of the information obtained from the superimposed images was obtained from surgery or follow-up imaging studies performed after clinical evolution of the disease process. RESULTS: Reliable and reproducible registration was achieved in all patients. CT-TS superimposed images produced accurate localization of abnormal TS foci. Accuracy was limited primarily by variable relative displacements of the thoracoabdominal organs. For 10 sites in 8 patients, localization and/or characterization obtained from CT-TS images was confirmed by a reference technique. Superimposition enabled the localization of tumor sites that otherwise could not have been suspected from CT alone and allowed the characterization of CT suspicious masses and the confirmation of CT positive sites. Nonspecific tumor TS uptake sites were also localized. CONCLUSION: With standard CT and dual-isotope SPECT acquisitions, SPECT-CT fusion is feasible in the thoracoabdominal region without the use of external markers. Fused images were validated in 8 patients for 10 sites. The use of this technique could probably improve the management and care of patients with endocrine carcinoma.

Gastric emptying is accelerated in obese type 2 diabetic patients without autonomic neuropathy.

OBJECTIVE: To clarify the impact of type 2 diabetes mellitus on the gastric emptying rate. MATERIAL AND METHODS: Using a double-isotope scintigraphic technique, we assessed the gastric emptying of a standard liquid-solid meal in 13 obese type 2 diabetic patients without autonomic neuropathy (age: 47.4 +/- 8.6 yr, body mass index: 33.9 +/- 4.8 kg/m(2), glycaemia: 9.1 +/- 2.6 mmol/l) and in 7 controls with similar sex ratio, age, BMI and body fat distribution. RESULTS: The half gastric emptying time for the liquid phase was not significantly different between diabetic patients and controls (respectively: 52.7 +/- 14.5 min and 63.1 +/- 15.2 min). However, the half gastric emptying time for the solid phase was significantly shortened in diabetic patients versus controls (respectively 88.8 +/- 23.2 min in diabetic patients and 113.6 +/- 26.9 min in controls; p<0.04). Furthermore, a negative relationship was highlighted between the half gastric emptying time for the solid phase and basal glycaemia (r=-0.65, p<0.02) in diabetic patients. No significant relationship was found between gastric emptying parameters and cardiac autonomic nerve function, insulin or gastrin levels. CONCLUSION: Solid gastric emptying is accelerated in obese type 2 diabetic patients without patent autonomic neuropathy when compared to obese non diabetic patients.

What factors determine indium-111 antimyosin monoclonal antibody uptake in patients with myocardial infarction?

The intensity of indium-111 antimyosin monoclonal antibody uptake for visualization of myocardial infarction seems partially dependent on the state of the infarct related coronary artery. The aim of this study is to determine the factors which could account for the monoclonal antibody uptake variability. For this purpose, we investigated 27 patients (mean age 52.7 +/- 9.6 years) with a first proven myocardial infarction, by monoclonal antibody scintigraphy and coronary arteriography within the same period of time (7.12 +/- 6 days). The monoclonal antibody uptake was quantified by the heart/lung ratio on images recorded 24 h after injection. The infarct size was quantitatively estimated on wall motion analysis of twelve segments in 30 degree right anterior-oblique view with a radial method. The infarct related coronary artery state was assessed by the Thrombosis in Myocardial Infarction grade and the functional characteristics of collateral vessels by Rentrop's classification. These three variables as well as location of myocardial infarction, left ventricular ejection fraction, administration of a thrombolytic therapy, delay between myocardial infarction and monoclonal antibody scintigraphy were studied using non parametric test, or by linear regression method in order to determine whether these factors would influence the heart/lung ratio. None of these parameters except infarct size was related to heart/lung ratio. Consequently, monoclonal antibody uptake is only dependent on the extent of infarcted myocardium and the intensity of uptake cannot predict the patency of an infarct related coronary artery.

Assessment of divided renal function by renography. Validation in patients with separate urine collections from each kidney.

Divided renal function was measured by 99mTc-DTPA renography using a gamma camera and a computer-assisted program. In 14 patients with permanent bilateral ureterostomies (7) or temporary ureteric catheterization (7), split renal function was calculated by analysis of the initial phase of the kidney activity-time curve and measured simultaneously by conventional clearance techniques. A high correlation was found between individual clearances measured by computation and by the conventional procedure. The correlation coefficient between the results obtained by the two techniques was 0.94 (P less than 0.001). A high correlation was also shown to exist between the computed clearance and the renal uptake of mercury after administration of 197HgCl. It is concluded that 99mTc-DTPA is particularly useful for the measurement of divided renal function without the need for urine collection.

Improvement of the amplitude image through statistical filtering.

In order to perform automatically the thresholding of the amplitude image obtained by phase analysis, a filter based on the probability density of the amplitude is proposed. It generates the image of the significant amplitude by setting to zero the amplitude if its square is lower than 4a0 log(1/alpha)/N where a0 is the mean of the signal, alpha the risk of error and N the number of frames. The power of the test is discussed and the modification of the filter for pre-processed data is provided.

Cluster analysis for automatic image segmentation in dynamic scintigraphies.

An original and entirely automatic algorithm is proposed to select regions of interest (ROIs) on dynamic scintigrams. This algorithm is based on factor analysis and on cluster analysis. It consists of first extracting the orthogonal factor images of the series using factor analysis of correspondence. These factor images are then automatically segmented in ROIs using a hierarchical ascendant classification procedure. The distance used for the classification is the 'minimum added intra-class variance' distance. This algorithm has been implemented on a fast computer dedicated to nuclear medicine (Nodecrest Micas V system). The time of calculation on 1000 pixels from 40 images is less than 5 min when three factor images are used. This algorithm is validated using a numerical phantom and is illustrated using renal (99Tcm DTPA) and cardiac (equilibrium gated angiography) dynamic scintigraphies. The results show that the algorithm is able to recognize the bladder, the renal cavities and the renal parenchyma on the renal series, and the ventricules and the atria on the cardiac series.

Comparison of phase analysis with factor analysis in equilibrium gated radionuclide angiography.

This study is the intercomparison of phase analysis (PA), factor analysis of dynamic structures (FADS) and Karhunen-Loeve analysis (KLA) in the diagnosis of regional wall motion abnormalities, RWMA, of the LV. One hundred and twenty eight patients with proven or suspected CAD have been investigated by both X-ray angiography and radionuclide equilibrium angiography performed in the LOA view. FADS and KLA are performed twice, once on the whole-image (WI-FADS, WI-KLA), and once on the LV ROI (LV-FADS, LV-KLA) as suggested by Pavel. Resulting images and factors are interpreted by a well trained observer. In an attempt to quantify LV-FADS images, two numeric parameters, P1 and P2, are defined. They measure the relative weight of the so-called ventricular factor for 2 and 3 factor analysis, respectively. A ROC curve is calculated for each method, taking X-ray angiography as the gold-standard. The areas under the ROC curves are estimated by the maximum likelihood method and are compared using a test described by Hanley which takes into account the correlation between the responses. The areas are: 0.90 for PA, 0.84 for WI-FADS, 0.86 for LV-FADS, 0.83 for WI-KLA, 0.86 for LV-KLA, 0.65 for P1 and 0.72 for P2. The observed differences are significant (at 5% level) between PA and WI-FADS and between FA and WI-KLA; whereas they are not between PA and LV-FADS, between PA and LV-KLA and between LV-FADS and LV-KLA. The diagnostic value of the two numeric parameters is poor.(ABSTRACT TRUNCATED AT 250 WORDS)

The objective evaluation of the phase image: a comparison of different automated methods.

One hundred and twenty eight patients with suspected or proven CAD were investigated using both X-ray ventriculography and equilibrium gated radionuclide angiography. In order to diagnose regional wall motion abnormalities, the parametric images obtained by Fourier analysis of the radionuclide images were analysed by different automated methods based on the measurement of the homogeneity of the phase values within the LV ROI. The effect of a diastolic frames exclusion, smoothing the original data, weighting the phase histogram, using Bacharach's error corrected phase distribution functions, using different descriptors of the spread of the phase histograms or distribution functions were tested. Using the results of the X-ray examination as the gold standard, ROC curves were plotted for each method. The ROC curves were modelled by a binormal model using the maximum likelihood method. Statistical tests were applied on the area under the ROC curves. The results show that the diagnostic value of the automated methods depends mainly on the way the histograms or distribution functions are described and to a lesser extent on the type of histograms or distribution functions used. The best result is obtained after smoothing, diastolic frames exclusion, weighting the phase histogram by the amplitude and describing it by its standard deviation. Nevertheless, this result is not significantly different from the result obtained by visual analysis of the phase and amplitude images.

Shape preserving three-dimensional display of myocardial scintigraphic data.

A three-dimensional display has been developed which is specifically suited to the visualization of myocardial single photon emission tomographic (SPET) data. A set of radial maxima voxels, representative of the whole left ventricle uptake and shape is first extracted by cylindrical and spherical sampling of the short axis slices. A three-dimensional representation of these voxels is then obtained, with hues depicting the uptake amount and shades (i.e. intensity and saturation) depicting the shape. This technique is suitable for 201Tl and 99TCm-hexakis-2-methoxyisobutyl isonitrile (99TCm-sestamibi) myocardial images. It is proposed as an aid to interpreting myocardial SPET as it enables the physician to distinguish simultaneously the actual shape, the extent and the severity of perfusion defects on a single frame.

Visualization of myocardial infarction 6 h after injection of 111In-antimyosin antibodies using a blood pool subtraction technique.

111In-antimyosin antibodies are capable of visualizing myocardial infarction (MI). Because of slow blood clearance, images are usually recorded 24 or 48 h postinjection. In this pilot study, a blood pool subtraction technique, which makes it possible to visualize MI 6 h postinjection, is validated. Twenty-five patients with proven MI (16 anterior, 9 inferior) were imaged a few minutes, 6 and 24 h after an injection of 111 MBq 111In-labelled antimyosin antibodies. Three planar views are obtained each time. Using software which performs the geometric registration, the grey level normalization and the subtraction of images, the blood pool image (obtained a few minutes postinjection) is subtracted from the 6 h image. The resulting image is the blood pool corrected 6 h image. The 24 h images and the blood pool corrected 6 h images were interpreted blindly and the number of correct, incorrect and impossible MI localizations was counted. The number of correct localizations is 19/25 for the standard 24 h images and 22/25 for the blood pool corrected 6 h images. Then, with this blood pool subtraction method, it is possible to visualize MI 6 h postinjection. This has to be taken into account when discussing the role of antimyosin scintigraphy in the management of patients with MI.

[Thyroid cancer in Champagne-Ardenne: 1967-1984. Epidemiologic findings in a regional register]. / Les cancers thyroïdiens en Champagne-Ardenne: 1967-1984. Exploitation épidémiologique d'un registre régional.

Between 1967 and 1984, 600 cases of clinically diagnosed thyroid carcinoma were collected in an area (Champagne-Ardenne) of about 1,500,000 inhabitants. During this period, the complete collection of the cases was progressively ensured by involving all the general practitioners and by creating a cooperative multidisciplinary group. The collected data were sex, age at diagnosis, histological classification and clinical extension in TNM system. We found 19 patients with previous neck irradiation. Thyroid cancer was diagnosed in association with thyrotoxicosis in 36 patients: 13 Graves disease and 23 nodular hyperthyroidism. Incidence rates were estimated on a well defined population of two districts (850,000 inhabitants) and limited to the last four years. The following results were obtained: incidence 4.3/100,000/year, age-specific incidence progressively increasing up to a value of 10/000,000/year in the course of the fifth decade. Sex-ratio was 0.26.

Interest of direct radionuclide cystography in repeated urinary tract infection exploration in childhood.

108 children with repeated urinary tract infection were examined both with direct contrast cystography and radionuclide cystography. There was a good correlation between the two procedures in the majority of the cases (79), but in 21 cases, direct radionuclide cystography alone was positive and for 8 other children, direct contrast cystography showed a low-grade vesico-ureteric reflux even though radionuclide cystography was negative. When comparing the two procedures and taking into consideration the age of the patients we find that radionuclide cystography is more sensitive to detect vesico-ureteric reflux in the younger population (p < 0.02). This advantage is less clear for older children who more often present a low-grade reflux. Low radiation exposure is also a great advantage of radionuclide cystography, but anatomic definition is better with contrast cystography. It seems thus that the two procedures complement rather than rival each other. Their respective interest for evaluation of repeated urinary tract infection in children therefore depends on age, attain-ability of the procedure, and the possibility of a bladder or ureteral abnormality. Quite a few authors consider radionuclide cystography as at least as valid as contrast cystography, and even more sensitive. We have attempted to compare both procedures and to determine their respective role in repeated urinary tract infection exploration.

Detection of subclinical abdominal hernia by peritoneal scintigraphy.

This study investigated the incidence of subclinical abdominal hernia in patients starting peritoneal dialysis (PD). From April 1995 to August 1999, every new patient without clinical evidence of abdominal leakage underwent peritoneal scintigraphy. A total of 59 patients were enrolled in the study. Imaging of the peritoneal cavity was performed by mixing 74 MBq (2 mCi) of 99 m technetium sulfur colloid with 2 L of 1.36% dextrose peritoneal dialysis solution. Sequential gamma camera static images were obtained at 0 minutes, 60 minutes, and after drainage. Ten abdominal hernias (2 diaphragmatic leaks, 8 inguinal hernias) were observed in ten patients (6 males, 4 females; mean age: 65.1 years). One patient with diaphragmatic leak recovered partial renal function and stopped continuous ambulatory peritoneal dialysis (CAPD); the other was switched to automated peritoneal dialysis (APD). Among the eight patients with inguinal hernia, six had no clinical manifestations within eight months of follow-up. Two patients became symptomatic at 15 months and 25 months respectively. They underwent surgical repair. In CAPD patients without obvious abdominal hernias, peritoneal scintigraphy at onset of dialysis discovered 17% positive cases. The technique of scintigraphy is safe, with a low radiation exposure. Surgical repair for maintenance on CAPD is not always necessary, and a change in the PD strategy may be useful.

Bone scan and chemonucleolysis.

This study is based on 20 patients who underwent bone scanning before and after chemonucleolysis (CN) for a herniated lumbar disk. It shows that chymopapain, the proteolytic enzyme used for CN, does not induce early or late bone lesions of the adjacent vertebral plates. Abnormal uptake by one of the vertebral plates indicates a "chemical discitis." The pattern observed on the bone scan is different from the one presented by patients with bacterial spondylitis.

Comparison of phosphatase isoenzymes PAP and PSA with bone scan in patients with prostate carcinoma.

The aim of this study was to assess the diagnostic value of five biological markers--prostate acid phosphatase (PAP), prostate specific antigen (PSA), tartrate resistant (Tr-ACP), and tartrate labile (TI-ACP) acid phosphatases, and alkaline phosphatase bone isoenzyme (B-ALP)--for the detection of bone metastases in patients with prostate carcinoma. Using the Tc-99m HMDP bone scans of 80 patients scored from 0 (normal) to 2 (diffuse bone involvement) as the "gold standard," a receiver operating characteristic (ROC) analysis was performed. This method allows the determination of different threshold values (corresponding to different couples of sensitivity and specificity) for the assays. An ROC curve comparison was also performed. Results show that B-ALP is the best test for such detection (area under the ROC curve = 0.93; Spearman Rank correlation with bone scan r' = 0.81). Among the other markers, PSA was found to be the best (area under the ROC curve = 0.81; Spearman Rank correlation with bone scan r' = 0.58). In addition to the prostatic tumor markers (PSA and PAP), we suggest the use of the low-cost B-ALP assay in the follow-up of prostate carcinoma patients to determine the optimum moment to perform a bone scan. A normal result of this assay indicates a very low probability of bone metastasis; conversely, raising of B-ALP concentration must lead to a bone scan.

Immunoscintigraphy with indium-111 labeled monoclonal antibodies: the importance of a good display method.

A major drawback of In-111-labeled monoclonal antibodies (MoAb) is the presence of intense liver, renal, and bone marrow nonspecific activity. This makes the display of the images hardly optimal and their visual interpretation difficult. In this study, the "intrinsic color scale" (which consists of selecting the limits of the color scale as the highest and the lowest pixel value of the image) was compared to a new, simple algorithm for the determination of the limits of the color scale. This algorithm was based on the count density in the iliac crest areas. OC-125 or anti-CEA In-111 MoAb F(ab')2 fragments were used in 32 patients with suspected recurrence of ovarian (19 patients) or colorectal cancer (13 patients). Final diagnosis was assessed by surgery (21 patients), biopsy (five patients), or followup (six patients). A 10-minute abdomino-pelvic anterior view was recorded two days after injection. These views are displayed using the two methods and interpreted by two observers. Using their responses in each quadrant of the pelvis, the authors calculated two ROC curves. The comparison of the ROC curves showed better performances for the new method. For example, for the same specificity (73%), the sensitivity of the new method was significantly better (78% versus 68%). This result confirmed the importance of a good methodology for displaying immunoscintigraphic images.

Quantitative comparison of prone and supine myocardial SPECT MIBI images.

The myocardial count distribution and the stress/rest ratio distribution were compared between prone and supine Tc-99m MIBI myocardial SPECT acquisitions. Ninety-nine male patients with a low stress supine inferior wall count underwent stress and rest acquisitions in the supine and prone positions successively. For each study, values depicting the inferior, anterior, septal, and lateral wall counts were extracted from a medioventricular normalized circumferential profile and underwent a statistical analysis (Student's paired t-test). On prone imaging, when compared to supine imaging, counts showed a highly significant mean relative increase of 11% +/- 1% in the inferior wall and of 7% +/- 1% in the septum. Conversely, these counts showed a significant mean relative decrease of 4% +/- 1% in the anterior wall and of 3% +/- 1% in the lateral wall. Moreover, the inferior wall stress/rest ratio showed a highly significant mean relative increase (6% +/- 2%). The prone position is probably preferable for interpreting the inferior wall and septum, where relative counts are enhanced, as with TI-201, and because the inferior stress-rest discrepancies are reduced in that position. But the anterior and lateral wall information is impaired in the prone position. The authors suggest, in case of a low stress supine inferior count, the combination of both positions, which is feasible with Tc-99m MIBI, in order to prevent a misleading interpretation.

[Role of clinical manifestations, the exercise test and exertion angioscintigraphy in the diagnosis of coronary disease. A multivariate study]. / Place de la clinique, de l'épreuve d'effort et de l'angioscintigraphie d'effort dans le diagnostic de maladie coronaire. Une étude multivariée.

Data of clinical examination, exercise electrocardiography and stress radionuclide angiography in 102 patients referred for assessment of chest pain was included in a logistic regression to optimise the diagnosis of coronary artery disease with coronary angiography as the reference investigation. None of the patients had other cardiac problems nor previous myocardial infarction. In the absence of symptoms exercise testing was continued until at least 80 p. 100 of the theoretical maximal heart rate was attained. Each patient was characterised by the value of the logistic function or probability of coronary artery disease. A threshold value corresponding to 80 p. 100 sensitivity was determined by the technique of ROC graphs. The significant variables were: a clinical variable--the type of chest pain as assessed by the clinical history; two radionuclide angiographic variables--the ejection fraction at peak effort and the corrected variation of ejection fraction between rest and stress, that is not taking into account possible decreases at the last increment of exercise. Coronary patients can be identified with an 80 p. 100 sensitivity and 77 p. 100 specificity on these criteria. This specificity is greater than that obtained by clinical examination and exercise electrocardiography alone (65 p. 100). Stress radionuclide angiography may therefore reduce the number of unnecessary coronary angiographies.