Diagnosis of breast cancer: contribution of US as an adjunct to mammography.

PURPOSE: To determine the value of ultrasonography (US) as an adjunct to mammography for the diagnosis of breast cancer. MATERIALS AND METHODS: In a 2-year prospective study, 4,811 mammograms were classified according to level of suspicion of malignancy. Targeted US was performed to analyze (a) circumscribed lesions, possibly cysts; (b) palpable lesions visible at mammography; (c) palpable lesions not visible at mammography; and (d) nonpalpable lesions visible at mammography. After US was performed in 1,103 cases (23%), cases were reclassified for level of suspicion. RESULTS: In 338 cases, breast cancer was diagnosed. The sensitivity of mammography for all 4,811 cases was 83%; the specificity was 97%. After US, the combined sensitivity increased to 91%, with a specificity of 98%. The increase was significant (P < .001). The increase in sensitivity was highest among women younger than 50 years. The positive predictive value for mammography was high (72%), which reflects a high threshold for biopsy; this may have augmented the yield of US. CONCLUSION: The use of US as an adjunct to mammography resulted in an increase in diagnostic accuracy. Its contribution to the diagnosis of breast cancer in this study was 7.4%.

Assessment of the progression of emphysema by quantitative analysis of spirometrically gated computed tomography images.

RATIONALE AND OBJECTIVES: The authors assessed the progression of pulmonary emphysema by means of quantitative analysis of computed tomography images. METHODS: Twenty-three patients suffering from emphysema due to an alpha 1-antitrypsin deficiency, aged 45 +/- 7 years and exsmokers, were scanned twice with a 1-year time interval. At 90% of the vital lung capacity, slices with a thickness of 1.5 mm were acquired at the level of the carina and 5 cm above the carina; slices with a thickness of 1 cm were acquired 5 cm below the carina. The entire lung was scanned spirally at a respiratory status, corresponding with 75% of the total lung capacity at baseline. The mean lung densities (MLD) were calculated in an objective manner with new analytic software featuring automated detection of the lung contours. RESULTS: Mean lung densities decreased by 14.2 +/- 12.0 Hounsfield units (HU; P < 0.001) above the carina, by 18.1 +/- 14.4 HU (P < 0.001) at the carina level, by 23.6 +/- 15.0 HU (P < 0.001) below the carina, and by 12.8 +/- 22.2 HU (P < 0.01) for the entire lung. The decrease in MLD was most obvious in the lower lung lobes. For the same patient group, the annual decrease in the forced expiratory volume (FEV1) and the carbon monoxide-diffusion were 120 +/- 190 mL (P < 0.01) and 10 +/- 70 mmol/kg/minute ( P < 0.2), respectively. No significant correlation was found between the decrease in MLD and the decrease in FEV1. CONCLUSIONS: Progression of emphysema can be assessed in an objective manner based on the mean lung density (MLD), measured from computed tomography volume scans as well as from single-slice scans. Mean lung density has proved to be more sensitive than FEV1 and carbon monoxide-diffusion.

Quantification of pulmonary and systemic blood flow by magnetic resonance velocity mapping in the assessment of atrial-level shunts.

The objective of this study was to asses the feasibility and accuracy of magnetic resonance (MR) velocity mapping to calculate pulmonary-to-systemic flow ratio (Qp:Qs) in patients with a suspected or diagnosed atrial-level shunt. During a one-year period, all patients referred to our department for further evaluation of an atrial-level shunt underwent the same imaging protocol. Multiphase-multisection gradient-echo MR image sets of the heart were acquired to measure left and right ventricular stroke volumes for validation. Ascending aorta and main pulmonary artery volume flow were measured with MR velocity mapping. Qp:Qs ratios were calculated from both stroke volume data and flow data. Twelve patients, including 6 children, were studied. Six patients had an established diagnosis of atrial septal defect, and the other 6 patients were suspected to have an atrial-level shunt. Measurements of left and right ventricular stroke corresponded closely with those of aortic (r = 0.98) and pulmonary flow (r = 0.99) respectively, and Qp:Qs flow ratios agreed with stroke volume ratios (r = 0.92). In 5 patients with a suspected shunt, the diagnosis could be rejected. Shunts were demonstrated in the other 7 patients. M(r) velocity mapping offers an accurate method to measure aortic and pulmonary artery volume flow that can be useful in the evaluation of atrial-level shunts, in order to establish a definite diagnosis and/or to quantify the Qp:Qs ratio.

Evaluation of cardiac function with magnetic resonance imaging.

A large body of evidence has accumulated to substantiate the accuracy of functional MR measurements of both ventricles. Because of good accuracy and superior reproducibility, MR imaging may be considered the gold standard for in vivo quantification of left and right ventricular ejection fraction, myocardial mass, and wall stress. New prospects for functional MR imaging include determination of the end-systolic volume-pressure relation as an index of myocardial contractility. The ability of MR imaging to detect wall motion disturbances may be enhanced further by combining myocardial tagging techniques with finite element analysis. Conventional MR imaging is limited by long examination times, but recent ultrafast modifications of echo-planar imaging allow completion of a functional heart study within seconds. Implementation of ultrafast MR imaging will greatly increase the usefulness of MR imaging for routine evaluation of cardiac function.

Accuracy and precision of quantitative digital coronary arteriography: observer-, short-, and medium-term variabilities.

Coronary arteriograms are increasingly acquired and stored in digital format, which allows instantaneous review of the pictorial data during the cardiac catheterization procedure. To support the angiographer in choosing the optimal sizes of the recanalization devices and studying the efficacy of the recanalization procedures, we have developed a new analytical software package (Automated Coronary Analysis = ACA) on the Philips DCI (-SX) digital cardiac imaging system. The ACA-package allows the objective and reproducible assessment of the morphologic and functional severity of coronary obstructions. Required user interaction is limited to the definition of the start and end points of the coronary segment to be analyzed. Automated contour detection is based on the use of first and second derivative functions along scanlines perpendicular to the automatically computed vessel pathline in the first iteration and perpendicular to the initial contours in the second iteration. These derivative functions have been modified based on the line spread function of the X-ray imaging chain, which is of particular importance for the accurate measurement of small vessel sizes. Phantom studies have indeed demonstrated that vessel sizes down to 0.66 mm can be measured accurately and reproducibly. Inter- and intraobserver variability studies have demonstrated a variability in the obstruction diameter of 0.11 mm and 0.10 mm, respectively, and in the percent diameter stenosis of 5.64% and 3.18%, respectively. These variability studies have been extended to short-term studies with repeated acquisition in the same angiographic views after 5 min and to medium-term studies with repeated acquisition in the initial angiographic views at the end of the catheterization procedures. With these standardized repeated acquisition and analysis procedures, the variabilities in the obstruction diameters increased to 0.19 and 0.18 mm, respectively, and remained below 6% in the percent diameter stenosis (5.61% and 5.28%, respectively). With an analysis time of approximately 15 sec on the DCI-SX, an efficient tool is now available in the catheterization laboratory for the objective and reproducible assessment of vessel dimensions and changes therein as a result of recanalization procedures.

Cardiac first-pass and myocardial perfusion in normal subjects assessed by sub-second Gd-DTPA enhanced MR imaging.

To evaluate first pass in the right ventricular (RV) and left ventricular (LV) cavities and myocardial perfusion, subsecond MR imaging was performed in seven normal subjects following intravenous bolus injection of Gd-DTPA. After the baseline scans, sequential ECG-triggered images were obtained every three to four RR intervals. The procedure consisted of an initial presaturation pulse (150 degrees), and the acquisition time for one image was approximately 500 ms with 64 phase-encoding steps. After bolus administration of Gd-DTPA (0.05 mmol/kg body wt), progressively increasing signal intensities were observed in the RV cavity, the LV cavity, and the myocardial wall. Gadolinium DTPA enhanced subsecond MR offers temporal information of the first transit in the cardiac chambers and may provide useful clinical reference data for assessment of myocardial perfusion in patients with coronary artery disease.

Magnetic resonance imaging of myocardial infarction: correlation with enzymatic, angiographic, and radionuclide findings.

Spin-echo cardiac magnetic resonance imaging studies were performed in 20 patients with a first 7- to 14-day-old (mean 10) myocardial infarction. The magnetic resonance imaging findings were compared with coronary angiography (14 patients), myocardial enzyme release (18 patients), radionuclide angiography (19 patients), and thallium-201 perfusion scintigraphy (19 patients). Regional T2 relaxation times determined from the signal intensities at echo times 30 msec and 90 msec were significantly prolonged in the infarcted areas. Based on abnormal T2 times for every patient, a regional and a total myocardial damage score was determined. The infarct-related artery was correctly identified in 93% of patients by magnetic resonance imaging, in 79% of patients by thallium-201 scintigraphy, and in 62% of patients by radionuclide angiography. The total damage score correlated well with enzymatic infarct size (r = 0.75, p less than 0.001). The correlation between left ventricular end-systolic volume index determined by magnetic resonance imaging and by radionuclide angiography was r = 0.89 (p less than 0.002). The left ventricular end-systolic volume index correlated significantly with enzymatic infarct size (r = 0.72, p less than 0.001), total damage score (r = 0.68, p less than 0.002), and radionuclide left ventricular ejection fraction (r = -0.68, p less than 0.002). Correlations between the magnetic resonance damage score and the thallium-201 perfusion score were r = 0.60 (p less than 0.01) for the exercise images, and r = 0.72 (p less than 0.001) for the redistribution images. This study shows that spin-echo magnetic resonance imaging is quite comparable with the established noninvasive imaging modalities currently used in patients with acute myocardial infarction.

Magnetic resonance imaging of the heart: perfusion, function, and structure.

The use of interventional therapy in acute myocardial infarction has intensified the desire to obtain accurate information on regional myocardial perfusion. MR imaging using ultrafast techniques and contrast agents may be useful to estimate myocardial perfusion in patients with coronary artery disease. In addition, MR imaging with contrast agents is capable of defining the infarcted region and the area at risk after coronary artery occlusion. Quantitative evaluation of regional myocardial contractile function with and without pharmacologic stress testing further improves the utility of MR imaging in defining the effects of reperfusion therapy on dysfunctional myocardium and in detecting myocardial ischemia. Furthermore, cine MR techniques are now used extensively to assess cardiac function and volumes and to obtain flow velocity maps. Cardiac MR applications are evolving rapidly and the clinical significance is expanding.

Acute, subacute, and chronic myocardial infarction: quantitative analysis of gadolinium-enhanced MR images.

The value of gadolinium enhancement to enable detection of infarcted myocardium at T1-weighted magnetic resonance (MR) imaging was assessed in 84 patients after acute myocardial infarction (AMI). Five healthy subjects served as controls. All patients underwent MR imaging before and 20 minutes after administration of gadopentetate dimeglumine. Contrast enhancement of normal myocardium varied 7% +/- 4 after administration of gadopentetate dimeglumine. Mean intensity ratio after gadolinium enhancement in group 1 (imaging less than 1 week after AMI), group 2 (imaging 1-3 weeks after AMI), and group 3 (imaging 3-6 weeks after AMI) was significantly higher than before gadolinium enhancement. In group 4 (imaging more than 6 weeks after AMI), no significant difference was observed. After gadolinium enhancement, the intensity ratio was abnormally increased in 82% of the MR examinations in group 1, in 62% of group 2, in 58% of group 3, and in 12% of group 4. Gadolinium enhancement improved visualization of myocardial infarction at MR imaging up to 6 weeks after onset of symptoms and had a maximal effect within 1 week after AMI.

Magnetic resonance imaging in the diagnosis and evaluation of myocardial infarction.

Magnetic resonance (MR) imaging with the aid of MR contrast agents may be helpful to assess myocardial infarct size, the area at risk, and myocardial viability. MR contrast agents may also prove useful for evaluating myocardial perfusion with ultrafast MR imaging techniques. Dynamic cine MR imaging is an accurate method to assess regional myocardial dysfunction in ischemic heart disease. In addition, myocardial contraction can be determined by MR imaging under pharmacological stress or by direct tracking of wall motion with MR myocardial tagging. Combining the information from these MR imaging techniques provides a comprehensive evaluation of patients with coronary artery disease.

Acute myocardial infarction: comparison of T2-weighted and T1-weighted gadolinium-DTPA enhanced MR imaging.

Magnetic resonance images were obtained from 32 patients with acute myocardial infarction, using a four-echo technique (echo time (TE) = 30, 60, 90, and 120 ms) pregadolinium(Gd)-DTPA injection and a TE = 30 ms sequence pre- and post-Gd-DTPA. Intensity ratios of infarcted and normal myocardium were calculated, as were contrast-to-noise and signal-to-noise ratios. The four intensity ratios pre-Gd-DTPA were 1.20 +/- 0.15, 1.42 +/- 0.22, 1.78 +/- 0.38, and 1.99 +/- 0.60 for TE = 30, 60, 90, and 120 ms, respectively, and 1.42 +/- 0.19 post-Gd-DTPA (p = NS for post-Gd-DTPA vs TE = 60, p = 0.007 for TE = 90 vs TE = 120, p less than 0.0001 for all other comparisons). The four contrast-to-noise ratios pre-Gd-DTPA were 1.69 +/- 0.97, 2.69 +/- 1.13, 3.17 +/- 1.15, and 2.90 +/- 1.09 for TE = 30, 60, 90, and 120 ms, respectively, and 2.71 +/- 1.26 post-Gd-DTPA (p = NS for post-Gd-DTPA vs TE = 60, 90, and 120, p = NS for TE = 120 vs TE = 60 and 90, p less than 0.01 for all other comparisons). The four signal-to-noise ratios pre-Gd-DTPA were 8.67 +/- 1.47, 6.52 +/- 0.76, 5.20 +/- 0.64, 4.17 +/- 0.53 for TE = 30, 60, 90, and 120 ms, respectively, and 9.17 +/- 1.92 post-Gd-DTPA (p = 0.03 for post-Gd-DTPA vs TE = 30, p less than 0.0001 for all other comparisons). In conclusion, the detectabilities of acute myocardial infarction were similar at TE = 60 ms and at Gd-DTPA enhanced short-TE MR imaging. However, image quality proved to be superior using the Gd-DTPA enhanced short-TE technique.

Follow-up of regional myocardial T2 relaxation times in patients with myocardial infarction evaluated with magnetic resonance imaging.

Multi-echo spin-echo cardiac magnetic resonance imaging studies (echo times 30, 60, 90 and 120 ms) were performed in 19 patients with a 7-14-day (mean 10) old myocardial infarction and were repeated in 13 patients 4-7 months (mean 6) later. Also, 10 normal subjects were studied with magnetic resonance imaging. T2 relaxation times of certain left ventricular segments were calculated from the signal intensities at echo times of 30 and 90 ms. Compared to normal individuals, the mean T2 values on the early magnetic resonance images of the patients with inferior infarction showed significantly prolonged T2 times in the inferiorly localized segments, while on the follow-up magnetic resonance images the T2 times had almost returned to the normal range. Also the patients with anterior infarction showed significantly prolonged T2 times in the anteriorly localized segments on the early nuclear magnetic resonance images, but the T2 times remained prolonged at the follow-up magnetic resonance images. For every patient a myocardial damage score was determined, which was defined as the sum of the segmental T2 values in the patients minus the upper limit of normal T2 values obtained from the normal volunteers (= mean normal + 2SD). The damage score on both the early and late magnetic resonance imaging study correlated well with infarct size determined by myocardial enzyme release. Only the patients with an inferior infarction showed a significant decrease in damage score at follow-up magnetic resonance imaging. It is concluded that the regional T2 relaxation times are increased in infarcted myocardial regions and may remain prolonged for at least up to 7 months after the acute event, particularly in patients with an anterior infarction. These findings demonstrate the clinical potential of T2-weighted magnetic resonance imaging studies for detecting myocardial infarction, and estimating infarct size for an extended period after acute myocardial infarction.

Myocardial infarct size after reperfusion therapy: assessment with Gd-DTPA-enhanced MR imaging.

In 21 patients with proved acute myocardial infarction, the size of the infarct was estimated with serial magnetic resonance (MR) imaging after intravenous injection of gadolinium diethylenetriaminepentaacetic acid (DTPA) (0.2 mmol per kilogram of body weight). Early reperfusion after thrombolytic therapy or percutaneous transluminal coronary angioplasty performed during the acute phase of infarction was documented with coronary angiography in nine patients (group 1). In 12 patients (group 2), no reperfusion was achieved (n = 5) or no thrombolytic therapy was given (n = 7). All group 2 patients were considered to have no reperfusion. Infarct sizes measured with MR imaging were significantly smaller in group 1 than in group 2 at 8 days +/- 4 after infarct onset (8% +/- 5% vs 15% +/- 4%, respectively; P less than .001). Serial MR images showed individual variations in infarct size, findings that may be clinically significant. Estimation of infarct size with Gd-DTPA-enhanced MR imaging is accurate in demonstrating the effect of successful reperfusion therapy on infarct size.

Gadolinium-enhanced magnetic resonance imaging in acute myocardial infarction.

To evaluate the usefulness of the paramagnetic contrast agent Gadolinium-DTPA (diethylenetriaminepentaacetic acid) in Magnetic Resonance Imaging of acute myocardial infarction, we studied a total of 45 patients with a first acute myocardial infarction by ECG-gated magnetic resonance imaging before and after intravenous administration of 0.1 mmol/kg Gadolinium-DTPA. All patients received thrombolytic treatment by intravenous streptokinase. The magnetic resonance imaging studies were performed after a mean of 88 h (range 15-241) after the acute onset of acute myocardial infarction. Five patients without evidence of cardiac disease served as controls. Spin-echo measurements (TE 30 ms) were made using a Philips Gyroscan (0.5 Tesla) or a Teslacon II (0.6 Tesla). The 45 patients were divided into four groups of patients. In Group I (5 patients) Gadolinium-DTPA improved the detection of myocardial infarction by Gadolinium-DTPA. In Group II (20 patients) the magnetic resonance imaging procedure was repeated every 10 min for up to 40 min following administration of Gadolinium-DTPA. Optimal contrast enhancement was obtained 20-25 min after Gadolinium-DTPA. In Group III (27 patients) signal intensities were significantly higher in the patients who underwent the magnetic resonance imaging study more than 72 h (mean 120) after the acute event, suggesting increased accumulation of Gadolinium-DTPA in a more advanced stage of the infarction process. In Group IV (45 patients) Gadolinium-DTPA was administered in an attempt to distinguish between reperfused and nonreperfused myocardial areas after thrombolytic treatment for acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnostic significance of gadolinium-DTPA (diethylenetriamine penta-acetic acid) enhanced magnetic resonance imaging in thrombolytic treatment for acute myocardial infarction: its potential in assessing reperfusion.

The diagnostic value of gadolinium-DTPA (diethylenetriamine penta-acetic acid) enhanced magnetic resonance imaging in patients treated by thrombolysis for acute myocardial infarction was assessed in 27 consecutive patients who had a first acute myocardial infarction (14 anterior, 13 inferior) and who underwent thrombolytic treatment and coronary arteriography within 4 hours of the onset of symptoms. Magnetic resonance imaging was performed 93 hours (range 15-241) after the onset of symptoms. A Philips Gyroscan (0.5 T) was used, and spin echo measurements (echo time 30 ms) were made before and 20 minutes after intravenous injection of 0.1 mmol/kg gadolinium-DTPA. In all patients contrast enhancement of the infarcted areas was seen after Gd-DTPA. The signal intensities of the infarcted and normal values were used to calculate the intensity ratios. Mean (SD) intensity ratios after Gd-DTPA were significantly increased (1.15 (0.17) v 1.52 (0.29). Intensity ratios were higher in the 17 patients who underwent magnetic resonance imaging more than 72 hours after the onset of symptoms than in the 10 who underwent magnetic resonance imaging earlier, the difference being significantly greater after administration of Gd-DTPA (1.38 (0.12) v 1.61 (0.34). When patients were classified according to the site and size of the infarcted areas, or to reperfusion (n = 19) versus non-reperfusion (n = 8), the intensity ratios both before and after Gd-DTPA did not show significant differences. Magnetic resonance imaging with Gd-DTPA improved the identification of acutely infarcted areas, but with current techniques did not identify patients in whom thrombolytic treatment was successful.