Diseases of the prostate gland are common in dogs, accounting for up to 10% of the pathological conditions in sexually intact male dogs examined by veterinary surgeons.1 Among these, malignant neoplasias are rare, with estimated prevalences of prostate gland carcinoma of 0.2% and 0.6%.2 Because cancer of the prostate gland is highly aggressive, with macroscopic metastasis detected at necropsy in 80% of affected animals,3 an early diagnosis is crucial for the management of patients. In contrast to the United States, where most of the dogs are neutered, the percentage of sexually intact animals in Europe can be highly variable among countries. In some countries, most of the animals are gonadally intact4 and thus more prone to pathological conditions of the prostate gland. Moreover, dogs are the only animals other than humans that naturally develop prostate gland cancer; therefore, dogs can serve an important role for the study of prostate gland disease of humans.5 Thus, investigation of the prostate gland has been a focus of recent scientific studies.
A noninvasive method to diagnose prostate gland diseases in dogs relies on clinical examination, laboratory analysis, and diagnostic imaging. Radiographic and ultrasonographic findings are not pathognomonic for any prostate gland diseases.1 Contrast-enhanced ultrasonography has been described as an additional aid for use in differentiating benign from malignant prostate gland lesions,6 but this technique is not routinely used in veterinary medicine.
The incidence of prostate gland cancer is much higher in human medicine than in veterinary medicine, and the incidence of cancer progressively increases with age.7 Means of diagnosis with high specificity and sensitivity and that also can serve as adequate screening methods have been evaluated. Use of MRI to provide a combination of morphological and functional images has become the standard method for investigation of pathological conditions of the prostate gland.7 Morphological imaging (typically T2-weighted images and T1-weighted precontrast and postcontrast images) is commonly used for detection and localization of possible lesions, identification of changes after biopsy, and monitoring of disease. In addition, functional MRI (PW-MRI, DW-MRI, and spectroscopic imaging) have been recommended as potential complements.8 Perfusion-weighted MRI (or dynamic contrast-enhanced MRI) is widely used as a tool to discriminate between benign and malignant lesions9 and for accurate localization of tumors (primarily in the peripheral zone of the prostate gland), local staging of tumors, and detection of tumor recurrence.10
In human medicine, DW-MRI with corresponding quantification of the ADC value has been used to discriminate malignant neoplasia from normal prostate gland tissue or benign processes.11,12 Values for ADC correlate with the score of aggressiveness of prostate gland tumors.13,14
The availability of cross-sectional imaging modalities is increasing in veterinary medicine, and the use of such modalities to assess the prostate gland is garnering interest. There is a paucity of reports and lack of detailed description of the prostate gland and pathological conditions of the prostate gland. To the authors' knowledge, results of functional MRI of the prostate gland of clinically normal dogs have not been reported. Therefore, the objective of the study reported here was to assess the feasibility for use of PW-MRI and DW-MRI in the evaluation of the prostate gland of dogs in a clinical setting and to describe the perfusion pattern as well as the DW-MRI characteristics of the prostate gland in a sample of healthy sexually intact adult dogs. These data would provide baseline information for use in evaluation of pathological conditions of the prostate gland of dogs.
Supported by the Marie-Louise von Muralt Foundation. The authors declare that there were no conflicts of interest.
Apparent diffusion coefficient
Region of interest
Aloka Alpha 10 ultrasound machine, Hitachi Medical Systems Europe Holding AG, Zug, Switzerland.
7.5 MHz (5 to 10 MHz), Aloka UST-9120, Hitachi Aloka Medical America, Wallingford, Conn.
12 MHz (5 to 13 MHz), Aloka UST-5412, Hitachi Aloka Medical America, Wallingford, Conn.
Philips Ingenia scanner, Philips AG, Zurich, Switzerland.
dStream Flex M, phased-array detection, 6 channels, Philips AG, Zurich, Switzerland.
Omniscan, GE Healthcare AG, Glattbrugg, Switzerland.
Philips Intellispace Ingenia, Philips Medical System, Best, Netherlands.
SPSS Statistics, version 184.108.40.206, IBM Corp, Chicago, Ill.
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