Body CT and oncologic imaging

Radiological measurement of breast cancer metastases to lung and liver: comparison between WHO (bidimensional) and RECIST (unidimensional) guidelines

PURPOSE

Radiologic assessment of "response-to-treatment" during clinical trials of anticancer drugs has been conventionally based on bidirectional tumor measurement. Recently, the revised guidelines were published, which recommended unidirectional tumor measurements. The purpose of this study was to compare response to treatment between the two measurement techniques in breast cancer patients with lung and liver metastases.

METHOD

Contrast-enhanced computed tomography studies of 86 breast cancer patients who had lung (n = 27) and liver (n = 59) metastases and who were enrolled in a phase-III oncology trial were evaluated before initiation of treatment and at 6 months after treatment. Lesions were measured by subspecialist radiologists on digitized images using electronic calipers. The largest diameter of the lesions was extracted from bidimensional measurements. Response to treatment was categorized into one of four categories: complete response indicating lesion disappearance, partial response indicating >30% decrease in tumor diameter, or >50% reduction in tumor area, disease progression indicating >20% increase in tumor diameter, or >25% increase in tumor area, and stable disease (neither complete response, partial response, nor disease progression). Response to treatment between the two measurement techniques was compared statistically using the chi2 test.

RESULTS

Response to treatment was concordant in 76 patients between unidimensional and bidimensional measurement techniques. In 5 patients (2 lung and 3 liver metastases) the response assessment was improved using unidimensional criteria and in 5 patients (2 lung and 3 liver metastases) the response was worse using unidimensional guidelines. Thus, the overall response rate was 50% for both unidimensional and bidimensional measurement techniques. There was no statistical difference between the two techniques.

CONCLUSION

Unidimensional measurements are appropriate for measuring the size of liver and lung metastases for determining response to treatment during clinical testing of oncologic drugs.

Using a saline chaser to decrease contrast media in abdominal CT

OBJECTIVE

The purpose of this study was to compare hepatic tumor conspicuity on CT after injection of either 150 mL of contrast material or 100 mL of contrast material plus a 50-mL saline chaser.

SUBJECTS AND METHODS

We evaluated 86 hypoattenuating liver metastases in 26 patients. Patients underwent CT in two sessions separated by a mean of 85 days: one time with 150 mL of contrast material and the other time with 100 mL of contrast material followed by a 50-mL saline chaser. The order of the sessions was randomized. Contrast material was administered via power injector and matched for injection rate and delay time. Attenuation values were obtained from normal liver tissue and metastases and from the spleen, kidney, aorta, and inferior vena cava.

RESULTS

The 150 mL dose of contrast material caused slightly greater liver and tumor attenuation than 100 mL of contrast material with a chaser (mean hepatic attenuation, 95.6 vs 89.8 H, respectively; p < 0.03, paired t test; mean tumor attenuation, 53.2 vs 49.1 H, respectively; r = 0.71, p = 0.09). The difference in conspicuity of liver lesions was slightly greater with 150 mL than with 100 mL with a chaser (46.8 H vs 44.2 H; r = 0.46, p = 0.08, paired t test), but was of doubtful clinical significance (2.6 H). Kidney, spleen, and vascular structures enhanced more with 150 mL than with 100 mL and a chaser.

CONCLUSION

Using 100 mL of contrast material and a saline chaser did not result in a meaningful difference in liver parenchyma attenuation or lesion conspicuity compared with using 150 mL of contrast medium alone. Routine use of a chaser for abdominal CT may yield cost savings and a decreased risk of contrast nephropathy.

CT tumor measurement for therapeutic response assessment: comparison of unidimensional, bidimensional, and volumetric techniques initial observations

PURPOSE

To compare unidimensional, bidimensional, and volumetric techniques for evaluation of treatment response in patients with liver metastases from breast cancer in a phase III clinical trial.

MATERIALS AND METHODS

Helical computed tomographic (CT) studies in 38 patients with liver metastases from breast cancer who were enrolled in a phase III clinical trial were evaluated before treatment and at 6 months after treatment. Two subspecialty radiologists measured all lesions on transverse CT scans with use of electronic calipers according to both unidimensional and bidimensional criteria. Volumetric measurements were made by tracing individual lesions. Measurements of individual lesions were summed to obtain patient response, which was categorized as complete response, disappearance of lesions; partial response, greater than 30% decrease in tumor diameter (unidimensional), greater than 50% reduction in tumor area (bidimensional), or greater than 65% reduction in tumor volume (volumetric); disease progression, greater than 20% increase in tumor diameter, greater than 25% increase in tumor area, or greater than 73% increase in tumor volume: or stable disease (size response other than that of complete response, partial response, or disease progression).

RESULTS

In 37 patients, there was concordant treatment response with use of unidimensional and bidimensional techniques. Volumetric measurement produced results different from those of the unidimensional and bidimensional techniques in 12 and 13 patients, respectively. In six patients with partial response per unidimensional and bidimensional criteria, the response based on the volumetric technique was stable disease. In two patients with stable disease per bidimensional and unidimensional criteria, the response was partial response by volumetric measurement. In four patients with disease progression per bidimensional and unidimensional criteria, the response was stable disease per volumetric criteria.

CONCLUSION

Volumetric measurement of tumor burden gives different results for treatment response compared with that of the unidimensional or bidimensional technique in a considerable proportion of patients.

Administration of a CT division

A computed tomography (CT) division can be viewed as a business subsidiary of a larger corporation-the radiology department. While a large amount of radiologic literature has been devoted to specific CT techniques and applications, there has been less of a focus on the operational structure required to achieve quality and efficiency in a CT division. This report includes discussion of the managerial structure, equipment purchases, continuing education, protocols, billing, and quality assurance measures that can be used to administer a CT division.

The fusion of anatomic and physiologic imaging in the management of patients with cancer

Imaging is of major clinical importance in the noninvasive evaluation and management of patients with cancer. Computed tomography (CT) and other anatomic imaging modalities, such as magnetic resonance imaging (MRI) or ultrasound, have a high diagnostic ability by visualizing lesion morphology and by providing the exact localization of malignant sites. Nuclear medicine provides information on the function and metabolism of cancer. Over the last decade, there have been numerous attempts to combine data obtained from different imaging techniques. Fused images of nuclear medicine and CT (or to a lesser extent, MRI) overcome the inherent limitations of both modalities. Valuable physiologic information benefits from a precise topographic localization. Coregistered data have been shown to be useful in the evaluation of patients with cancer at diagnosis and staging, in monitoring the response to treatment, and during follow up, for early detection of recurrence. Time-consuming and difficult realignment and computation for fusion of independent studies have, until now, limited the use of registration techniques to pilot studies performed in a small number of patients. The development of the new technology of single photon emission computed tomography/CT and positron emission tomography/CT that allows for combined functional and anatomic data acquisition has the potential to make fusion an everyday clinical tool.

Fetus and uteroplacental unit: fast MR imaging with three-dimensional reconstruction and volumetry--feasibility study

In 22 fetuses, three-dimensional reconstruction was performed on the basis of T2-weighted magnetic resonance (MR) data sets by using a surface-rendering technique. Fetuses and uteroplacental units were segmented manually; volumes were calculated automatically. Three-dimensional reconstruction and volumetry of the fetus and uteroplacental unit are feasible with MR data sets. MR estimates correlated closely with ultrasonographic fetal biometric estimates and birth weight.

Recent advances in imaging endogenous or transferred gene expression utilizing radionuclide technologies in living subjects: applications to breast cancer

A variety of imaging technologies is being investigated as tools for studying gene expression in living subjects. Two technologies that use radiolabeled isotopes are single photon emission computed tomography (SPECT) and positron emission tomography (PET). A relatively high sensitivity, a full quantitative tomographic capability, and the ability to extend small animal imaging assays directly into human applications characterize radionuclide approaches. Various radiolabeled probes (tracers) can be synthesized to target specific molecules present in breast cancer cells. These include antibodies or ligands to target cell surface receptors, substrates for intracellular enzymes, antisense oligodeoxynucleotide probes for targeting mRNA, probes for targeting intracellular receptors, and probes for genes transferred into the cell. We briefly discuss each of these imaging approaches and focus in detail on imaging reporter genes. In a PET reporter gene system for in vivo reporter gene imaging, the protein products of the reporter genes sequester positron emitting reporter probes. PET subsequently measures the PET reporter gene dependent sequestration of the PET reporter probe in living animals. We describe and review reporter gene approaches using the herpes simplex type 1 virus thymidine kinase and the dopamine type 2 receptor genes. Application of the reporter gene approach to animal models for breast cancer is discussed. Prospects for future applications of the transgene imaging technology in human gene therapy are also discussed. Both SPECT and PET provide unique opportunities to study animal models of breast cancer with direct application to human imaging. Continued development of new technology, probes and assays should help in the better understanding of basic breast cancer biology and in the improved management of breast cancer patients.