H. Mark Saunders

Noninvasive Monitoring of MurineTumor Blood Flow During and After PhotodynamicTherapy Provides Early Assessment of Therapeutic Efficacy

Purpose: To monitor tumor blood flow noninvasively during photodynamic therapy (PDT) and to correlate flow responses with therapeutic efficacy. Experimental Design: Diffuse correlation spectroscopy (DCS) was used to measure blood flow continuously in radiation-induced fibrosarcoma murine tumors during Photofrin (5 mg/kg)/PDT (75 mW/cm2, 135 J/cm2). Relative blood flow (rBF; i.e., normalized to preillumination values) was compared with tumor perfusion as determined by power Doppler ultrasound and was correlated with treatment durability, defined as the time of tumor growth to a volume of 400 mm3. Broadband diffuse reflectance spectroscopy concurrently quantified tumor hemoglobin oxygen saturation (SO2). Results: DCS and power Doppler ultrasound measured similar flow decreases in animals treated with identical protocols. DCS measurement of rBF during PDT revealed a series of PDT-induced peaks and declines dominated by an initial steep increase (average ± SE: 168.1 ± 39.5%) and subsequent decrease (59.2 ± 29.1%). The duration (interval time; range, 2.2-15.6 minutes) and slope (flow reduction rate; range, 4.4 -45.8% minute−1) of the decrease correlated significantly (P = 0.0001 and 0.0002, r2 = 0.79 and 0.67, respectively) with treatment durability. A positive, significant (P = 0.016, r2 = 0.50) association between interval time and time-to-400 mm3 was also detected in animals with depressed pre-PDT blood flow due to hydralazine administration. At 3 hours after PDT, rBF and SO2 were predictive (P ≤ 0.015) of treatment durability. Conclusion: These data suggest a role for DCS in real-time monitoring of PDT vascular response as an indicator of treatment efficacy.

Signalment, history, and outcome of cats with gastrointestinal tract intussusception: 20 cases (1986–2000)

OBJECTIVE To determine signalment, history, and outcome of cats with gastrointestinal tract intussusception and to identify physical examination, diagnostic imaging, surgical, histologic, and necropsy findings in affected cats. DESIGN Retrospective case series. ANIMALS 20 cats with intussusception. PROCEDURES Medical records were evaluated for information on signalment; history; physical examination, diagnostic imaging, surgical, histologic, and necropsy findings; and outcome. RESULTS Ten cats were < 1 year old, and 9 were >or= 6 years old. Anorexia (14/17), lethargy (12/17), and vomiting (12/17) were the most common reasons for examination. Dehydration (13/18), poor body condition (12/18), signs of abdominal pain (8/18), and an abdominal mass (8/18) were the most common physical examination findings. Abdominal radiography revealed intestinal obstruction in all 10 cats in which it was performed; abdominal ultrasonography revealed intussusception in all 7 cats in which it was performed. The most common intussusception was jejuno-jejunal (8/20), and no intussusceptions were found proximal to the duodenum. Eleven of 13 cats that underwent laparotomy required intestinal resection and anastomosis. Histologic examination revealed intestinal lymphoma or inflammatory bowel disease in 7 of 8 cats >/= 6 years old and idiopathic intussusception in 7 of 8 cats < 1 year old. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that in cats, intussusception has a bimodal age distribution, is most commonly jejuno-jejunal, often requires surgical resection and anastomosis, is often associated with alimentary lymphoma or inflammatory bowel disease in older cats, and is readily diagnosed by means of ultrasonography.

ULTRASONIC DETECTION OF SPLENIC NECROSIS IN THE DOG

Ultrasonographic findings of splenic infarction and necrosis in three dogs are presented. Two previously unreported ultrasonographic patterns are identified: (1) Focal, hypoechoic or isoechoic, circular, wellmarginated nodular masses with peripheral lesions causing deformation of the splenic margin. (2) Diffuse hypoechoic or heteroechoic coarse/“lacy” parenchymal pattern with no deformation of margin. The presence of gas within the splenic parenchyma of one dog was detected by both radiography and ultrasonography. Ultrasonographic patterns of splenic infarction in both man and the dog are discussed

Noninvasive monitoring hemodynamic responses in RIF tumors during and after PDT

Changes in blood flow and oxygenation during and after PDT provide information about tumor vessel and cellular damage. The characterization of these changes may improve our understanding of PDT mechanisms and help predict treatment efficacy. We have designed a hybrid system that can non-invasively measure in vivo hemodynamic changes and provide independent information about tumor oxygenation and blood flow. Diffuse correlation spectroscopy (DCS) monitors blood flow by measuring the optical phase shifts caused by moving blood cells, while diffuse photon density wave (DPDW) spectroscopy measures tissue absorption and scattering. When mounted on a camera, our unique probe allows non-contact measurements that avoid compressing the tumor and altering blood flow. An optical filter mounted in front of the camera lens cut off light below 650nm, which allowed monitoring of blood flow during PDT. The utility of the hybrid system was demonstrated by monitoring the hemodynamic changes during and after PDT in mice bearing the experimental radiation-induced fibrosarcoma (RIF). For the first time, we non-invasively and continually monitored the in vivo flow changes during PDT. Relative oxygen consumption was calculated using flow values measured by DCS and oxygenation measured by a broadband absorption spectrometer. During PDT an initial rapid increase in blood flow was found, followed by a decrease and slow recovery. After PDT, substantial and continued reductions in blood saturation, blood flow and oxygen consumption were found after 3 hours, suggesting that permanent damage to tumor cells and blood vessels had occurred. The comparison of flow values after PDT as measured by DCS and by Power Doppler ultrasound (CWFA) demonstrated that both techniques non-invasively detected similar global changes in tumor blood flow or perfusion after PDT.

Ultrasonography of Abdominal Cavitary Parenchymal Lesions

Cavitary parenchymal lesions are composed of varying amounts of soft tissue, fluid, and/or gas. These cavitary lesions are focal or multifocal and therefore readily detected ultrasonographically. The ultrasonographic appearance of cystic and noncystic cavitary lesions are described. Differential diagnoses for these cavitary lesions in abdominal organs are listed.