PET and functional anatomic fusion imaging in lung and breast cancers

Multimodal breast cancer imaging using coregistered dynamic diffuse optical tomography and digital breast tomosynthesis

Diffuse optical tomography (DOT) is emerging as a noninvasive functional imaging method for breast cancer diagnosis and neoadjuvant chemotherapy monitoring. In particular, the multimodal approach of combining DOT with x-ray digital breast tomosynthesis (DBT) is especially synergistic as DBT prior information can be used to enhance the DOT reconstruction. DOT, in turn, provides a functional information overlay onto the mammographic images, increasing sensitivity and specificity to cancer pathology. We describe a dynamic DOT apparatus designed for tight integration with commercial DBT scanners and providing a fast (up to 1 Hz) image acquisition rate to enable tracking hemodynamic changes induced by the mammographic breast compression. The system integrates 96 continuous-wave and 24 frequency-domain source locations as well as 32 continuous wave and 20 frequency-domain detection locations into low-profile plastic plates that can easily mate to the DBT compression paddle and x-ray detector cover, respectively. We demonstrate system performance using static and dynamic tissue-like phantoms as well as in vivo images acquired from the pool of patients recalled for breast biopsies at the Massachusetts General Hospital Breast Imaging Division.

Combined optical and X-ray tomosynthesis breast imaging

PURPOSE

To explore the optical and physiologic properties of normal and lesion-bearing breasts by using a combined optical and digital breast tomosynthesis (DBT) imaging system.

MATERIALS AND METHODS

Institutional review board approval and patient informed consent were obtained for this HIPAA-compliant study. Combined optical and tomosynthesis imaging analysis was performed in 189 breasts from 125 subjects (mean age, 56 years ± 13 [standard deviation]), including 138 breasts with negative findings and 51 breasts with lesions. Three-dimensional (3D) maps of total hemoglobin concentration (Hb(T)), oxygen saturation (So(2)), and tissue reduced scattering coefficients were interpreted by using the coregistered DBT images. Paired and unpaired t tests were performed between various tissue types to identify significant differences.

RESULTS

The estimated average bulk Hb(T) from 138 normal breasts was 19.2 μmol/L. The corresponding mean So(2) was 0.73, within the range of values in the literature. A linear correlation (R = 0.57, P < .0001) was found between Hb(T) and the fibroglandular volume fraction derived from the 3D DBT scans. Optical reconstructions of normal breasts revealed structures corresponding to chest-wall muscle, fibroglandular, and adipose tissues in the Hb(T), So(2), and scattering images. In 26 malignant tumors of 0.6-2.5 cm in size, Hb(T) was significantly greater than that in the fibroglandular tissue of the same breast (P = .0062). Solid benign lesions (n = 17) and cysts (n = 8) had significantly lower Hb(T) contrast than did the malignant lesions (P = .025 and P = .0033, respectively).

CONCLUSION

The optical and DBT images were structurally consistent. The malignant tumors and benign lesions demonstrated different Hb(T) and scattering contrasts, which can potentially be exploited to reduce the false-positive rate of conventional mammography and unnecessary biopsies.

Clinical biomarkers of angiogenesis inhibition

INTRODUCTION

An expanding understanding of the importance of angiogenesis in oncology and the development of numerous angiogenesis inhibitors are driving the search for biomarkers of angiogenesis. We review currently available candidate biomarkers and surrogate markers of anti-angiogenic agent effect.

DISCUSSION

A number of invasive, minimally invasive, and non-invasive tools are described with their potential benefits and limitations. Diverse markers can evaluate tumor tissue or biological fluids, or specialized imaging modalities.

CONCLUSIONS

The inclusion of these markers into clinical trials may provide insight into appropriate dosing for desired biological effects, appropriate timing of additional therapy, prediction of individual response to an agent, insight into the interaction of chemotherapy and radiation following exposure to these agents, and perhaps most importantly, a better understanding of the complex nature of angiogenesis in human tumors. While many markers have potential for clinical use, it is not yet clear which marker or combination of markers will prove most useful.

Multidisciplinary frontiers in breast cancer management: a surgeon's perspective

The current paradigm of breast cancer management may be altered significantly over the coming years by the adoption of new treatment schema and devices outside of the surgical arena. New advances in breast cancer imaging will improve our ability to detect early-stage disease but also will assist in monitoring treatment outcomes and support the development of nonsurgical ablation techniques. These advances, some already in use, include a 3-dimensional adaptation of digital mammography, color Doppler ultrasonography that can visualize neovascularization in growing tumors, contrast-enhanced magnetic resonance imaging with improved accuracy for the detection of occult cancers, a specialized approach to positron emission tomography designed for use on the breast, and the development of nanoparticle contrast agents that can be visualized with near-infrared light. Systemic therapy, which revolutionized breast cancer management in the last half of the 20th century, is being reconceptualized, with attention turning to adjusting the timing of chemotherapy. Dose-dense regimens are being tested, and there also is interest in so-called metronomic chemotherapy in which very low doses are given on a very frequent schedule, resulting in reduced toxicity and treatment outcomes that reflect an antiangiogenic mode of action. Finally, the possibility of a breast cancer vaccine continues to intrigue and excite physicians and patients alike, with the promise of enlisting the body's own immune system to seek out and destroy cancer cells and/or prevent the development of future disease. It will be important for surgeons to stay aware of all developments that may improve the care of their patients and to be true surgical oncologists rather than merely surgical technicians.

Whole body positron emission tomography/computed tomography staging of metastatic choroidal melanoma

PURPOSE

To evaluate whole-body positron emission tomography (PET)/computed tomography in staging of patients with metastatic choroidal melanoma.

DESIGN

Interventional non-randomized clinical study.

METHODS

Twenty patients were referred for whole-body 18-fluoro-2-deoxy-D-glucose (FDG) PET/computed tomography imaging because of suspected metastatic choroidal melanoma. PET/computed tomography images were studied for the presence and distribution of metastatic melanoma. Subsequent biopsies were performed to confirm the presence of metastatic disease.

RESULTS

Twenty patients underwent PET/computed tomography. Eighteen were imaged because of abnormal clinical, hematologic, or radiographic screening studies during the course of their follow-up after plaque brachytherapy or enucleation. Two were imaged before treatment of their primary tumor. PET/computed tomography revealed or confirmed metastatic melanoma in eight (40%) of these 20 patients. The mean time from initial diagnosis to metastasis was 47 months (range 0 to 154). The most common sites for metastases were the liver (100%), bone (50%), lung (25%), lymph nodes (25%), and subcutaneous tissue (25%). Cardiac, brain, thyroid, and posterior abdominal wall lesions (12.5%) were also noted. Six patients (75%) had multiple organ involvement. No false positives were noted. PET/computed tomography imaging also detected benign lesions of the bone and lymph nodes in three patients (15%). All patients had hepatic metastases and liver enzyme assays were abnormal in only one (12.5%) of eight patients.

CONCLUSIONS

PET/computed tomography imaging is a sensitive tool for the detection and localization of hepatic and extra-hepatic (particularly osseous) metastatic choroidal melanoma.