Prospective investigation of positron emission tomography in lung nodules

PURPOSE

Solitary pulmonary nodules (SPNs) are commonly identified by chest radiographs and computed tomography (CT). Biopsies are often performed to evaluate the nodules further. An accurate, noninvasive diagnostic test could avoid the morbidity and costs of invasive tissue sampling. We evaluated the ability of fluorine-18 deoxyglucose positron emission tomography (FDG-PET) to discriminate between benign and malignant pulmonary nodules in a prospective, multicenter trial.

METHODS

Eighty-nine patients who had newly identified indeterminate SPNs on chest radiographs and CT were evaluated with FDG-PET. PET data were analyzed semiquantitatively by calculating standardized uptake values (SUVs) as an index of FDG accumulation and also by a visual scoring method. PET results were compared with pathology results.

RESULTS

Sixty SPNs were malignant and 29 were benign. Using SUV data, PET had an overall sensitivity and specificity for detection of malignant nodules of 92% and 90%. Visual analysis provided a slightly higher, but not statistically significant, sensitivity of 98% and lower specificity of 69%. For SPNs < or = 1.5 cm (34 of 89), the sensitivity and specificity of SUV and visual analysis were 80% and 95% and 100% and 74%, respectively.

CONCLUSION

FDG-PET can accurately characterize indeterminate SPNs. PET imaging provides a noninvasive method to evaluate indeterminate SPNs, which can reduce the need for invasive tissue biopsy.

Half-Fourier, three-dimensional technique for dynamic contrast-enhanced MR imaging of both breasts and axillae: initial characterization of breast lesions

PURPOSE

To evaluate the ability of asymmetric half-Fourier three-dimensional (3D) magnetic resonance (MR) imaging to characterize signal intensity changes in breasts and axillae after contrast material injection and to compare the spatial resolution and measured signal intensity change of asymmetric and symmetric (keyhole) partial Fourier techniques.

MATERIALS AND METHODS

Imaging was performed in 28 adult patients by collecting a single full-Fourier 3D data set with bolus injection of contrast material during the last 10 seconds followed by collection of six half-Fourier 3D data sets without interimage delays. Postcontrast keyhole and half-Fourier images were formed from the same full-Fourier raw data set.

RESULTS

The asymmetric half-Fourier 3D technique maintained the spatial resolution and lesion signal intensity of the full-Fourier image, whereas the 50% keyhole method degraded the spatial resolution by a factor of two and decreased the lesion signal intensity by 19% for a 2 x 2-pixel region of interest. Histopathologic correlation was attained in 32 lesions in 28 patients. Sensitivity was 100% (five of five) and specificity was 89% (24 of 27).

CONCLUSION

The asymmetric half-Fourier 3D MR imaging technique allows imaging of both breasts and axillae without loss of lesion contrast or temporal resolution and provides the maximum spatial resolution and lesion signal intensity attainable for the views sampled.

Dynamic sequential 3D gadolinium-enhanced MRI of the whole breast

Dynamic contrast-enhanced 2D MR imaging of the breast has shown high sensitivity and specificity for the detection and characterization of breast lesions. We investigated the ability of a dynamic fast 3D MR imaging technique that repeatedly scans the whole breast in 44-s intervals without an interscan delay time to obtain similar sensitivity and specificity as 2D imaging. Fifty-six patients scheduled for breast biopsy were entered into the study, and 83 lesions detected by 3D dynamic scanning were biopsied. Dynamic 3D contrast-enhanced breast imaging with subtraction detected and correctly classified all 23 cancers, and 44 of the 60 benign lesions yielding a sensitivity of 100%, a specificity of 73%, and a 100% predictive negative value. The enhancement profiles of metastatic lymph nodes were similar to those of primary cancer. This technique allowed detection of multifocal and multicentric lesions and did not require a prior knowledge of lesion location. These results indicate that dynamic contrast-enhanced 3D MRI of the whole breast is a useful and economically feasible method for staging breast cancer, providing a comprehensive noninvasive method for total evaluation of the breast and axilla in patients considering breast conservation surgery or lumpectomy.

Sonographic diagnosis of unsuspected gallbladder cancer: imaging findings in comparison with benign gallbladder conditions

OBJECTIVE

Several sonographic findings were analyzed to determine their significance in distinguishing gallbladder cancer from benign conditions of the gallbladder. The analyzed findings were gallstone number and size; floating stones; displaced stones; wall thickening, irregularity, and echogenicity; mucosal plaque; intraluminal mass; gallbladder-replacing mass; invasive gallbladder mass; gallbladder mucosal discontinuity; hyperechoic gallbladder mucosa; and submucosal or transmural echolucency.

MATERIALS AND METHODS

Sonograms of 20 patients with unsuspected, pathologically proven gallbaldder cancer and 65 patients with benign gallbladder conditions (predominantly acute or chronic cholecystitis) were retrospectively assessed by two observers who were unaware of experimental conditions. Gallstone number and size were assessed, and the presence of floating stone (neither settling nor wall-adherent), displaced stone (lifted from the gallbladder wall by mass or focal wall thickening), wall irregularity, mucosal plaque, intracystic mass, and gallbladder-replacing or invasive mass was evaluated. The echogenicity pattern of the gallbladder wall was characterized, and its thickness was measured and classified as normal/mildly thickened (< 7 mm) or moderately/severely thickened (> or = 7 mm). In addition, the gallbladder wall was evaluated for discontinuous mucosal echo, hyperechoic mucosa, submucosal or mural echolucency, and pericholecystic fluid collection. Sonographic findings were compared by the Mann-Whitney test for nonparametric variables and by Student's t test for continuous variables.

RESULTS

Solitary gallstone, displaced stone, intraluminal mass, gallbladder-replacing or invasive mass, and discontinuity of the mucosal echo were all statistically significantly more common in patients with gallbladder cancer (.001 < p < .05). Mucosal plaque and wall irregularity were nonspecific findings. Gallbladder wall thickening by itself was nonspecific, although associated echolayering, transmural or submucosal edema, or a distinctly specular mucosal lining favored benign etiologies.

CONCLUSION

Several sonographic findings were significantly more common in patients with gallbladder cancer compared with patients with benign gallbladder conditions. Assessment of these signs may be helpful in distinguishing gallbladder cancer from benign conditions of the gallbladder.