Transrectal ultrasound-integrated spectral optical tomography of hypoxic progression of a regressing tumor in a canine prostate

Use of transrectal ultrasonography for assessment of the size and location of prostatic carcinoma in dogs

OBJECTIVE

To evaluate the use of transrectal ultrasonography (TRUS) for the assessment of prostatic tumors in dogs and to compare results for TRUS with results for other imaging modalities.

ANIMALS

10 client-owned male dogs.

PROCEDURES

Client-owned dogs identified with prostatic carcinoma were enrolled. Fluoroscopy, transabdominal ultrasonography (TAUS), TRUS, and MRI were performed on all dogs. Tumor measurements, urethral penetration (identification of abnormal tissue within the urethral lumen), and tumor extension into the urinary tract were recorded for all imaging modalities. Agreement between results for MRI (considered the criterion-referenced standard) and results for other modalities were compared.

RESULTS

Median body weight of the 10 dogs was 26.3 kg (range, 9.4 to 49.5 kg). No complications were encountered during or after TRUS. Significant moderate to good agreements (intraclass correlation coefficients, 0.60 to 0.86) among TAUS, TRUS, fluoroscopy, and MRI were identified for tumor length and height. Assessments of urethral penetration and tumor extension into the bladder with TRUS did not differ significantly from those made with MRI and were superior in terms of absolute agreement with MRI when compared with those for TAUS.

CONCLUSIONS AND CLINICAL RELEVANCE

TRUS was successfully and safely used to evaluate prostatic carcinoma in dogs. There was moderate to good agreement with MRI results for tumor height and length measurements, and TRUS was found to be superior to TAUS for some assessments. Transrectal ultrasonography can be considered an adjunctive imaging modality for the performance of prostatic interventional procedures or assessment of response to treatment.

Bench to bedside molecular functional imaging in translational cancer medicine: to image or to imagine?

Ongoing research on malignant and normal cell biology has substantially enhanced the understanding of the biology of cancer and carcinogenesis. This has led to the development of methods to image the evolution of cancer, target specific biological molecules, and study the anti-tumour effects of novel therapeutic agents. At the same time, there has been a paradigm shift in the field of oncological imaging from purely structural or functional imaging to combined multimodal structure-function approaches that enable the assessment of malignancy from all aspects (including molecular and functional level) in a single examination. The evolving molecular functional imaging using specific molecular targets (especially with combined positron-emission tomography [PET] computed tomography [CT] using 2- [(18)F]-fluoro-2-deoxy-D-glucose [FDG] and other novel PET tracers) has great potential in translational research, giving specific quantitative information with regard to tumour activity, and has been of pivotal importance in diagnoses and therapy tailoring. Furthermore, molecular functional imaging has taken a key place in the present era of translational cancer research, producing an important tool to study and evolve newer receptor-targeted therapies, gene therapies, and in cancer stem cell research, which could form the basis to translate these agents into clinical practice, popularly termed "theranostics". Targeted molecular imaging needs to be developed in close association with biotechnology, information technology, and basic translational scientists for its best utility. This article reviews the current role of molecular functional imaging as one of the main pillars of translational research.

Tumor functional and molecular imaging utilizing ultrasound and ultrasound-mediated optical techniques

Tumor functional and molecular imaging has significantly contributed to cancer preclinical research and clinical applications. Among typical imaging modalities, ultrasonic and optical techniques are two commonly used methods; both share several common features such as cost efficiency, absence of ionizing radiation, relatively inexpensive contrast agents, and comparable maximum-imaging depth. Ultrasonic and optical techniques are also complementary in imaging resolution, molecular sensitivity, and imaging space (vascular and extravascular). The marriage between ultrasonic and optical techniques takes advantages of both techniques. This review introduces tumor functional and molecular imaging using microbubble-based ultrasound and ultrasound-mediated optical imaging techniques.