Biomedical subjects

L Pace

Publications and source records attributed to L Pace.

At least 37 records · Page 2Linked to original sources

PubMed1999

Influence of left ventricular cavity size on clinical presentation in hypertrophic cardiomyopathy.

The aim of this study was to assess whether left ventricular (LV) cavity size relates to functional impairment and syncope in patients with hypertrophic cardiomyopathy (HC). LV diastolic dysfunction influences functional limitation in HC. A reduced LV end-diastolic dimension may underlie impaired diastolic properties and be implicated in hemodynamic syncope. Eighty-two consecutive patients with HC (off drugs, in sinus rhythm) underwent echocardiography to measure LV end-diastolic dimension in the short-axis view (indexed to the body surface area) and radionuclide angiography (n = 50) to calculate peak filling rate (normalized to stroke counts/s). Patients in New York Heart Association functional classes II to IV had smaller LV end-diastolic dimension (23.2 +/- 2.6 vs 25.5 +/- 2.5 mm/M2, p = 0.0001) and lower peak filling rate (4.3 +/- 1.4 vs 5.1 +/- 1.3 stroke counts/s, p = 0.036) than those in New York Heart Association class I. LV end-diastolic diameter was correlated to peak filling rate (r = 0.37; p = 0.008). The most potent predictors of functional limitation were LV end-diastolic dimension (relative risk [RR] 0.63, confidence interval [CI] 0.45 to 0.88; p = 0.008), age (RR 1.09, CI 1.03 to 1.17; p = 0.003), and LV thickness score (RR 1.08, CI 1.02 to 1.13; p = 0.003). LV cavity size was smaller in patients with functional limitation irrespective of obstruction and hypertrophy. Patients with differed from those without a history of syncope for a smaller LV end-diastolic dimension (23.2 +/- 2.5 vs 25.0 +/- 2.7 mm/M2, p = 0.008), which was the only independent predictor of syncope (RR 0.77, CI 0.63 to 0.95; p = 0.013). Thus, a small LV cavity size is associated with functional limitation and history of syncope in HC.

Adolescent↗

PubMed1999

Determinants of aortic artifacts during transesophageal echocardiography of the ascending aorta.

BACKGROUND: The origin of artifacts of the ascending aorta during transesophageal echocardiography has not been widely studied. This study was undertaken to investigate in vivo whether anatomic features could determine the appearance of artifacts. METHODS AND RESULTS: Transesophageal echocardiograms of 46 patients studied for suspected dissection with proven diagnosis (30 patients with and 16 without ascending aortic dissection) were reviewed. The incidence of artifacts was 46%, and it was similar in patients with and those without dissection (chi-square 0.516; P = not significant). Artifacts were located in the aortic lumen twice as far from the transducer as the atrial-aortic interface. The aortic diameter was larger in patients with than in those without artifacts (6.4 +/- 1.1 vs 4.2 +/- 0.9 cm, P <.001). An aortic diameter >5 cm and an atrial-aortic ratio </=0.6 predicted the artifact appearance with good sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy; these parameters reached a value of 100% by analysis only of patients without dissection. CONCLUSIONS: An ascending aortic diameter >5.0 cm that exceeds the left atrial diameter with an atrial-aortic ratio </=0.6 creates in vivo the conditions for the reverberation of the atrial-aortic interface within the aorta. Therefore, in patients with such anatomic features, artifacts must be suspected in the presence of linear structures within the aorta.

Aortic Dissection↗

PubMed1999

Tc-99m sestamibi scintigraphy in multiple myeloma.

Tc-99m sestamibi imaging was performed in two patients with multiple myeloma. Focal areas of increased uptake in one patient and diffuse skeletal uptake in the second patient were found. Tc-99m sestamibi appears to identify bone marrow and osteolytic involvement in multiple myeloma.

Adult↗

PubMed1999

Detection of focal myeloma lesions by technetium-99m-sestaMIBI scintigraphy.

BACKGROUND AND OBJECTIVE: The tracer tachnetium-99m-2-methoxy-isobutyl-isonitrile (Tc99m-sestaMIBI) has recently been shown to concentrate in some neoplastic tissues, including myeloma. We investigated the diagnostic capacity and limits of this procedure in tracing focal myeloma lesions, and compared them with those of conventional radiological procedures (Xr). DESIGN AND METHODS: We studied 55 patients suffering from multiple myeloma (MM) or solitary plasmacytoma in different stages and clinical conditions, or from monoclonal gammopathy of undefined significance (MGUS), by whole body scans obtained 10 minutes after injection of 555 MBq of Tc99m-sestaMIBI. Scans were defined as normal (physiological uptake only), diffuse (presence of bone marrow uptake), or focal (localized areas of uptake), and were compared to conventional skeletal Xr. RESULTS: Thirty patients showed no focal areas of Tc99m-sestaMIBI uptake; this group consisted of 5 patients with MGUS, 6 with MM in stage IA and 2 in stage IIA, 11 patients studied after effective chemotherapy and 6 in early relapse. Twenty-five patients showed one or more spots of focal uptake: all of them had active disease (untreated, resistant or relapsing MM). In the setting of tracing focal lesions, Tc99m-sestaMIBI scans were concordant with the radiological examination in 38 patients and discordant in 17. Among the latter, in 4 cases Tc99m-sestaMIBI revealed focal lesions not detected by Xr, and in 13 cases lytic areas detected by Xr did not show Tc99m-sestaMIBI uptake. INTERPRETATION AND CONCLUSIONS: In untreated patients, the number of lesions revealed by Tc99m-sestaMIBI was comparable to that shown by Xr, while in pretreated patients Tc99m-sestaMIBI traced a number of lesions lower than that detected by Xr. The reason for this discrepancy is that Tc99m-sestaMIBI traces only active lesions. Tc99m-sestaMIBI limitations in identifying focal lesions may derive from the dimension of the smallest traceable lesion (about one centimeter), and from the possibility that focal plasma cell localizations in collapsed bone may not be visualized due to inadequate vascularization. Tc99m-sestaMIBI scintigraphy is an interesting tool for diagnosing, staging and following up focal myeloma lesions, in the bone as well as in soft tissues. It is more specific than conventional Xr in identifying sites of active disease.

Adult↗

PubMed1999

Primary eyelid mucinous adenocarcinoma of eccrine origin.

To report a case of mucinous adenocarcinoma of the eyelid. A 70-year-old man presented with a lesion of his lower left eyelid, which had been growing over the past few years. An excisional biopsy was performed. The lesion was incompletely excised and recurrence at the excision site was observed at a 3-month follow-up visit. A histopathological examination of the excised specimen showed it to be a mucinous adenocarcinoma of eccrine origin. Primary mucinous adenocarcinoma of the eye lid is a rare malignant sweat gland tumor with a high incidence of local recurrence. It has to be differentiated from other adenocarcinomas which may rarely metastasize to the skin.

Adenocarcinoma, Mucinous↗

PubMed1999

[Autoimmune hemolytic anemia in chronic hepatitis C virus infection treated with alpha-interferon: a therapy-related event or extra-hepatic immunologic manifestation?].

We report a case of Coombs' positive autoimmune haemolytic anaemia occurring in a patient with chronic hepatitis C virus infection, after five months of alpha-interferon administration. Prednisolone treatment induced a complete remission of both clinical and hematological findings after two months, while Coombs' tests became negative after three months. This points out the possibility of an additional unusual extrahepatic autoimmune feature during the course of hepatitis C virus infection.

Anemia, Hemolytic, Autoimmune↗

PubMed1998

Examination for heat-labile, heat-stable, and Shiga-like toxins and for the eaeA gene in Escherichia coli isolates obtained from dogs dying with diarrhea: 122 cases (1992-1996).

OBJECTIVE: To examine Escherichia coli isolates obtained from dogs dying with diarrhea for heat-labile, heat-stable, and Shiga-like toxins and for the eaeA gene, which is associated with attaching and effacing lesions. DESIGN: Retrospective study. ANIMALS: 122 dogs. PROCEDURE: E coli isolates were tested by means of dot-blot hybridization of DNA extracts of cultured bacteria. Medical records of dogs from which E coli isolates with virulence genes had been isolated were examined, and histologic findings and evidence of intercurrent bacterial and viral infections were recorded. RESULTS: None of the E coli isolates obtained from these dogs produced heat-labile, heat-stable, or Shiga-like toxins; however, E coli isolates from 44 of 122 dogs were found to have the eaeA gene. Histologically, multifocal bacterial adherence to the epithelium and epithelial necrosis and detachment were seen in colonic specimens from 20 of 44 (45%) dogs. Escherichia coli was the sole pathogen identified in 15 of 44 (34%) dogs. Intercurrent pathogens, including canine parvovirus (n = 19), Clostridium perfringens (8), rotavirus (5), hookworms (3), coccidia (3), and Salmonella agona (1), were identified in the remaining 29 (66%) dogs. CLINICAL IMPLICATIONS: Attaching and effacing E coli can be a primary or secondary pathogen in dogs with diarrhea. Antibiotic treatment is indicated in dogs with diarrhea because of the possibility that it is primarily bacterial in origin and because, even if it is primarily viral in origin, there may be secondary bacterial infection.

Adhesins, Bacterial↗

PubMed1998

Noninvasive evaluation of left ventricular diastolic function in hypertrophic cardiomyopathy.

Diastolic dysfunction is common in hypertrophic cardiomyopathy (HC). Previous studies suggest that Doppler transmitral flow velocity profiles, and the left atrial (LA) M-mode echogram can be used noninvasively to evaluate left ventricular (LV) diastolic function. However, this has not been proved in HC. In this study we determined the relation of Doppler transmitral flow velocity profiles and the LA M-mode echograms to invasive indexes of LV diastolic function in patients with HC. We studied 25 patients with HC, while off drugs, and calculated LA global and active fractional shortening and the slope of both early and late displacement of the posterior aortic wall during LA emptying by M-mode echocardiography. We calculated peak velocity of early (E) and atrial (A) filling, E to A ratio, and E-wave deceleration time by pulsed Doppler echocardiography, and simultaneous radionuclide angiography, LV pressures, time constant of isovolumic relaxation tau, and the constant of chamber stiffness k by cardiac catheterization. The time constant of isovolumic relaxation tau correlated with the slope of early posterior aortic wall displacement (r = 0.59; p <0.01). LV end-diastolic pressure correlated with global LA fractional shortening (r = -0.75; p <0.001); the constant of chamber stiffness k correlated with active LA fractional shortening (r = -0.53; p <0.02). In a subset of 13 patients, in whom echocardiography and cardiac catheterization were performed simultaneously, similar results were found. LA M-mode recordings provide a more reliable noninvasive assessment of diastolic function in HC than mitral Doppler indexes.

Adolescent↗

PubMed1998

Successful coronary revascularization improves prognosis in patients with previous myocardial infarction and evidence of viable myocardium at thallium-201 imaging.

The role of coronary revascularization of dysfunctional myocardium with preserved thallium-201 uptake in determining the prognosis in patients after myocardial infarction remains to be defined. This study was designed to evaluate the effects of successful revascularization on survival and left ventricular (LV) function in patients with previous myocardial infarction and evidence of dysfunctional but still viable myocardium at rest-redistribution 201Tl imaging. Seventy-six consecutive patients with LV dysfunction related to previous myocardial infarction and evidence of viable myocardium at rest-redistribution 201Tl tomography were followed for 17+/-8 months. LV ejection fraction (EF) was assessed by radionuclide angiography at baseline and after 13+/-2 months. Thirty-nine patients were revascularized (group A) and 37 treated medically (group B). During the follow-up there were nine cardiac deaths. Survival rate was 97% in group A and 66% in group B (P<0.01). By Cox multivariate analysis, the extent of viable myocardium was the best predictor of cardiac death (chi2=8.67, P<0.01) and provided additional information to clinical and functional data (P<0.01). The inclusion of revascularization as a variable improved the global chi2 of the model from 14.1 to 21.9 (P<0.01). At follow-up, EF had improved by >/=5% in 16 patients. By multivariate logistic analysis, the extent of viable myocardium was the best predictor of EF improvement (chi2=15.49, P<0.001) and provided additional information to clinical and functional data (P<0.01). The inclusion of revascularization as a variable improved the global chi2 of the model from 16.8 to 22.5 (P<0.01). These results demonstrate that the total extent of dysfunctional myocardium with preserved 201Tl uptake is the strongest predictor of cardiac death in patients after myocardial infarction. Successful revascularization of dysfunctional but viable myocardium improves survival and LVEF in such patients.

Angiocardiography↗

PubMed1998

Different patterns of technetium-99m sestamibi uptake in multiple myeloma.

Technetium-99m 2-methoxyisobutylisonitrile (99mTc-MIBI) has been proposed as a potential tracer in patients with multiple myeloma (MM). The aims of this study were to evaluate the incidence of various patterns of diffuse 99mTc-MIBI uptake in patients with MM, to assess their relationship with clinical status and stage of disease, and to try to clarify the meaning of the diffuse bone marrow uptake of 99mTc-MIBI. Thirty-nine consecutive patients with MM were studied. Twenty-nine of these patients had active disease (13 in stage I, ten in stage II, and six in stage III) and ten were in remission after chemotherapy. Anterior and posterior whole-body scans were obtained 10 min after i.v. injection of 555 MBq of 99mTc-MIBI. The scans were classified as showing: pattern N, when only physiological uptake was present; pattern D, when diffuse bone marrow uptake was observed; pattern F, when areas of focal uptake of the radiotracer were evident; or pattern D+F, when both D and F patterns were observed. Diffuse bone marrow uptake was scored according to extension and intensity. Seven of the 39 patients (18%) showed pattern N, 18 (46%) pattern D, 2 (5%) pattern F, and 12 (31%) pattern D+F. Of the 32 patients with a positive 99mTc-MIBI scan (i.e. showing pattern D, F or D+F), 29 (91%) had active disease. Only three patients in remission showed pattern D, but with a very low bone marrow uptake score. Both extension and intensity of diffuse bone marrow uptake correlated with the amount of the monoclonal component and the percentage of bone marrow plasma cells. The distribution of the 99mTc-MIBI uptake patterns differed among patients in different stages of disease. Using as criteria for advanced stage the presence of either focal uptake (pattern F or D+F) or pattern D with a high score, high (90%) diagnostic accuracy was obtained. In conclusion, the patterns of 99mTc-MIBI uptake in patients with MM are related to both the clinical status and the stage of disease. The presence of focal uptake or of intense diffuse bone marrow uptake suggests that the patient has active and advanced stage disease, while a negative scan in a patient with MM clearly indicates remission.

Antibodies, Monoclonal↗

PubMed1998

Combined evaluation of rest-redistribution thallium-201 tomography and low-dose dobutamine echocardiography enhances the identification of viable myocardium in patients with chronic coronary artery disease.

The purpose of this study was to evaluate whether combined evaluation by discriminant analysis of rest-redistribution thallium-201 tomography and low-dose dobutamine echocardiography enhances the accuracy in identifying viable myocardium in patients with chronic coronary artery disease. Rest-redistribution 201Tl has high sensitivity but low specificity in identifying viable myocardium, while the opposite is true for low-dose dobutamine echocardiography. Forty-six patients underwent low-dose dobutamine echocardiography and rest-redistribution 201Tl tomography on the same day. Rest echocardiography was repeated at least 30 days (mean 40+/-20) after myocardial revascularization. Discriminant analysis was applied to the results of 201Tl tomography and dobutamine echocardiography to classify a/dyskinetic segments as viable or non-viable. In 92 a/dyskinetic segments that were revascularized, rest-redistribution 201Tl tomography yielded an accuracy of 75%, while the accuracy of dobutamine echocardiography was 70% (P<0.05). When discriminant analysis was used, the combined evaluation gave an accuracy of 83% (P<0.05 vs both tests). These findings demonstrate that low-dose dobutamine echocardiography and 201Tl imaging are useful and complementary techniques for identifying viable myocardium in patients with chronic coronary artery disease. Combined evaluation by discriminant analysis significantly improves accuracy, although the cost-effectiveness of such an approach remains to be determined.

Adrenergic beta-Agonists↗

PubMed1998

Pattern of left ventricular filling in hypertrophic cardiomyopathy. Assessment by Doppler echocardiography and radionuclide angiography.

AIMS: The left ventricle in hypertrophic cardiomyopathy is anatomically and functionally non-uniform. This study was undertaken to verify whether a heterogeneity in the pattern of diastolic filling can be detected along the left ventricular inflow tract in hypertrophic cardiomyopathy. METHODS AND RESULTS: Early (E) and late (A) diastolic velocities were recorded by Doppler echocardiography at mitral and at mid-ventricular level in 16 normal volunteers and 30 patients with hypertrophic cardiomyopathy. Patients with hypertrophic cardiomyopathy also underwent radionuclide angiography to assess left ventricular function. E wave decreased significantly in normal volunteers (80 +/- 15 to 60 +/- 14 cm x s(-1); P<0.001), but it increased in hypertrophic cardiomyopathy (76 +/- 22 to 87 +/- 28 cm x s(-1) P=0.04), whereas the A wave decreased similarly in both. By multivariate analysis, systolic asynchrony and the ejection fraction of left ventricular lateral wall were directly related to the pattern of early filling progression (r=0.656, F=9.467; P<0.002). Moreover, systolic asynchrony showed a univariate direct correlation with changes in E velocity (r=0.42; P=0.02). CONCLUSION: Many patients with hypertrophic cardiomyopathy have an acceleration of filling within the left ventricular inflow tract; this phenomenon is directly related to systolic asynchrony and ejection fraction of the left ventricular lateral wall, suggesting increased suction.

Adolescent↗

PubMed1998

Identification of viable myocardium in patients with chronic coronary artery disease using rest-redistribution thallium-201 tomography: optimal image analysis.

UNLABELLED: With the widely used 50% threshold, sensitivity is high, but specificity is low in detecting viable myocardium on 201Tl SPECT. In this study, we sought to identify the best threshold for semiquantitative 201Tl analysis. METHODS: Rest-redistribution 201Tl SPECT was performed in 46 patients with chronic coronary artery disease before and after myocardial revascularization. Regional function was evaluated by two-dimensional echocardiography before and after myocardial revascularization using a 3-point scale (1 = normal, 2 = hypokinetic, 3 = a/dyskinetic). Myocardial segments with abnormal systolic function were defined as viable if the systolic function score decreased > or = 1 after myocardial revascularization. A second group of 12 patients with chronic coronary artery disease constituted the validation population. Sensitivity-specificity curves, as well as receiver operating characteristic curves, for rest and redistribution mages were generated by varying the 201Tl uptake threshold. RESULTS: A 65% threshold uptake using resting images was found to be the best for detecting a/dyskinetic segments that improve after myocardial revascularization from those that do not improve. Sensitivity was lower with a 65% threshold (75%) than with a 50% threshold (90%, p < 0.05), but specificity was higher (76% versus 26%, p < 0.05) resulting in better accuracy (76% versus 57%, p < 0.05) and positive predictive value (77% versus 55%), while the negative predictive value was not different (69% versus 75%, p not significant). The area under the receiver operating characteristic curve was significantly (p < 005) larger for rest (0.80 +/- 0.05) as opposed to redistribution (0.72 +/- 0.05) images. Similar results were obtained in a subgroup of patients with low ejection fraction. Significant correlations between the percentage of revascularized viable segments and both the change in ejection fraction and in postrevascularization ejection fraction were found. When these findings were applied in the validation group, a gain in specificity, accuracy and positive predictive value was obtained with the 65% threshold compared with the 50% threshold. CONCLUSION: This study demonstrated that analysis of resting images and use of the 65% 201Tl uptake threshold is preferable for separating viable from not viable dyssynergic myocardial segments in patients with chronic coronary artery disease.

Case-Control Studies↗

PubMed1997

Surface treatment of indirect resin composite surfaces before cementation.

STATEMENT OF PROBLEM: Controversy surrounds the use of hydrofluoric acid to prepare precementation surfaces of indirect composites. PURPOSE: This study was conducted to compare effects of combining hydrofluoric or orthophosphoric acid with microetching as precementation treatments. MATERIAL AND METHODS: Nine specimens of three composite materials were prepared to simulate heat-cured indirect restorations. The specimen surfaces were prepared with one of three treatments. Adhesive Bond II and Twinlook cements were used to bond a phosphoric acid-etched disk of P50 to the treated surface. Analysis of variance and Scheffé tests were used to assess the bond strength data. Scanning electron microscopy and microscopic analysis of the fractured and treated surfaces were also performed. RESULTS: Bond strengths for all surface treatments did not significantly differ. Hybrids had a higher bond strength with etching than microfills, and mechanical roughening produced the greatest bond strengths with microfills. Microetching with orthophosphoric acid produced higher bond strengths than microetching with hydrofluoric acid on hybrids. CONCLUSIONS: Acid etching alone is not sufficient to produce effective bond strengths, and hydrofluoric acid treatments are detrimental to the resin composite.

Acid Etching, Dental↗

PubMed1997

Left ventricular function and perfusion in Becker's muscular dystrophy.

UNLABELLED: The aim of this study was to evaluate left ventricular (LV) perfusion and function in patients with Becker muscular dystrophy (BMD). METHODS: Fourteen male patients (age range 14-40 yr) with BMD were evaluated by 201Tl SPECT and radionuclide angiography both at rest and after dipyridamole stress test. RESULTS: All patients showed uptake defect demonstrated by 201Tl SPECT (mean 4.1 +/- 2.2 uptake defect/patient). Significant relationships (p < 0.05) were found between the number of uptake defects and rest LV ejection fraction (LVEF) (r = -0.54); peak filling rate (PFR) (r = -0.57) and dipyridamole LVEF (r = -0.65). Dipyridamole induced reversible uptake defects were found in 7/14 (50%) patients with BMD. The 14 patients were divided into two groups on the basis of the presence (Group A, n = 6) or the absence (Group B, n = 8) of severe irreversible uptake defect (i.e., < 50% 201Tl uptake). Group A showed lower values of PFR and LVEF when compared to patients of Group B. CONCLUSIONS: In patients with BMD there is a relatively high incidence of uptake defects and LV function (both at rest and after dipyridamole) appears to be related to the number of uptake defects. Moreover, the presence of severe irreversible uptake defects identifies a subgroup of patients with BMD characterized by a severely depressed LV function.

Adolescent↗

PubMed1997

Adenosine coronary vasodilation in coronary artery disease: technetium-99m tetrofosmin myocardial tomography versus echocardiography.

UNLABELLED: This study compared the results of adenosine 99mTc-tetrofosmin cardiac tomography with those of adenosine echocardiography in identifying patients with coronary artery disease (CAD) and in localizing individual stenosed, coronary vessels. METHODS: Twenty-six consecutive patients with suspected or known CAD had simultaneous adenosine (140 micrograms/Kg/min intravenously) 99mTc-tetrofosmin tomography and two-dimensional echocardiography. All patients had coronary angiography within 4 wk from imaging studies. Regional 99mTc-tetrofosmin activity was quantitatively measured in 78 coronary vascular territories and echocardiographic left ventricular function was assessed in corresponding regions. RESULTS: At coronary angiography one patient had normal coronary vessels, 12 patients one-vessel and 13 had multivessel disease (> or = 50% luminal stenosis). Among the 25 patients with CAD, 22 showed perfusion defects at adenosine 99mTc-tetrofosmin tomography (sensitivity 88%) and 17 had abnormal echocardiographic study (sensitivity 68%, p < 0.05 versus 99mTc-tetrofosmin). Agreement for the identification of patients with CAD between adenosine 99mTc-tetrofosmin tomography and echocardiography was observed in 21 (81%) of the total 26 patients, with a kappa value of 0.45. Overall sensitivity, specificity and diagnostic accuracy for detection of individual stenosed vessels were 79%, 88% and 83% for 99mTc tetrofosmin and 57%, 68% and 61% (all p < 0.05 versus 99mTc-tetrofosmin) for echocardiography. Concordance between adenosine 99mTc-tetrofosmin tomography and echocardiography in the detection of individual stenosed coronary vessels was observed in 57 (73%) of the 78 vascular territories, with a kappa value of 0.36. CONCLUSION: Adenosine-induced coronary vasodilation associated with quantitative 99mTc-tetrofosmin tomography is more accurate than adenosine echocardiography in identifying patients with CAD and in detecting individual stenosed coronary vessels.

Adenosine↗

PubMed1997

Fractional retention of technetium-99m-sestamibi as an index of P-glycoprotein expression in untreated breast cancer patients.

UNLABELLED: The multidrug-resistant phenotype is characterized by the reduced intracellular retention of several structurally and functionally unrelated cytotoxic compounds due to the energy-dependent pump activity of P-glycoprotein (Pgp). Because 99mTc-sestamibi is a suitable transport substrate of Pgp, we tested whether the time-dependent fractional retention of this tracer could be used as an index of Pgp expression in untreated breast carcinomas. METHODS: Twenty-seven patients with histologically confirmed breast carcinoma were intravenously injected with 740 MBq (20 mCi) of 99mTc-sestamibi, and static planar images of the breast were obtained at 10, 60 and 240 min. The fractional retention of 99mTc-sestamibi was then calculated as the ratios between 60 and 10 min (R60/10) and between 240 and 10 min (R240/10) of decay-corrected counts/pixel registered in the region of interest drawn around the tumor. Surgically excised tumors were then obtained from each patient, and Pgp levels were determined using 125I-labeled MRK16 monoclonal antibody and in vitro quantitative autoradiography. RESULTS: The fractional retention of 99mTc-sestamibi at 60 and 240 min was significantly higher in tumors with low Pgp levels (Group I, n = 18) as compared to that measured in tumors with high Pgp expression (Group II, n = 9) (p < 0.001). In particular, R60/10 values were 0.86 and 0.59 in breast carcinomas of Groups I and II, respectively, whereas the values of R240/10 were 0.56 and 0.25 in low- and high-Pgp-expressing tumors, respectively. CONCLUSION: The determination of fractional retention of 99mTc-sestamibi may be used as a simple functional test for Pgp expression in untreated breast cancer. A preliminary estimate of the sensitivity and the specificity of the test indicates its potential use in clinical practice to identify patients with a high probability of developing multidrug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

Assessment of myocardial viability in patients with chronic coronary artery disease. Rest-4-hour-24-hour 201Tl tomography versus dobutamine echocardiography.

BACKGROUND: To date, late redistribution after resting 201Tl injection has not been evaluated. In addition, the concordance between resting 201Tl imaging and dobutamine echocardiography in identifying viable myocardium has not been assessed. METHODS AND RESULTS: Forty patients with coronary artery disease underwent rest-4-hour-24-hour 201Tl tomography and dobutamine echocardiography (5 to 10 micrograms.kg-1.min-1). Late redistribution occurred in 46 (21%) of 219 persistent defects at 4 hours. Systolic function and contractile reserve were similar among persistent defects at 4 hours with and without late redistribution. Contractile reserve was more frequent in segments with normal 201Tl uptake (59%), completely reversible defects (53%), or mild to moderate defects at 4 hours (56%) compared with severe defects (14%; P < .02 versus all). Of 105 hypokinetic segments, 99 (94%) were viable by 201Tl, and 88 (84%) showed contractile reserve. In contrast, of 155 akinetic segments, 119 (77%) were viable by 201Tl, but only 34 (22%) had contractile reserve. Concordance between 201Tl and dobutamine was 82% in hypokinetic segments but 43% in akinetic segments. In 109 revascularized segments, positive accuracy for functional recovery was 72% for 201Tl and 92% for dobutamine, whereas negative accuracy was 100% and 65%, respectively. Sensitivity was 100% for 201Tl and 79% for dobutamine. CONCLUSIONS: Late redistribution occurs in one fifth of persistent defects at 4 hours, and it does not correlate to systolic function or contractile reserve. Dobutamine and 201Tl yield concordant information in the majority of hypokinetic segments, whereas concordance is low in akinetic segments. Dobutamine demonstrates higher positive accuracy and sensitivity in predicting recovery of dysfunctional myocardium, whereas 201Tl shows higher negative predictive accuracy but reduced positive accuracy.

Aged↗