Assessment of morphological changes in cerebral venous sinus of small animal models is important to gain insights of various disease conditions such as intracranial hypotension, Idiopathic intracranial hypertension (IIH), Cerebral venous sinus thrombosis, subdural hematoma etc. Photoacoustic Tomography (PAT), a fast-growing non-invasive hybrid imaging modality which combines high optical contrast and resolution in deep tissue imaging offers a novel, rapid and cost-effective way to analyze the morphological changes of venous sinus in comparison with the conventional imaging modalities. In this study, we examined the morphological changes of sagittal sinus in the rat brain due to intracranial pressure changes induced by Cerebrospinal fluid (CSF) extraction using low cost pulsed laser diode (PLD) based desktop (PAT) system. Our results indicate that the desktop PLD-PAT system can be employed to evaluate the changes in the cerebral venous sinus in preclinical models. We observed a ~30% average increase in the area of sagittal venous sinus from the baseline, when the CSF is extracted.
Conventional photoacoustic tomography (PAT) systems use bulky, expensive Q-switched Nd:YAG lasers which limits its usage in clinics. The low repetition rate of these lasers makes them not suitable for real-time imaging as well. Compact pulsed laser diodes (PLD) are being currently used for PAT systems due to their high repetition rates and compact in size. These lasers can be mounted inside the PAT circular scanning geometry making the PAT system more portable. Using acoustic reflector based single-element ultrasound transducer (SUTR), the scanning radius can be reduced thereby making the PAT system more compact. In this work, we present a portable, high frame rate, more compact second generation PLD-PAT system using eight SUTRs in circular scanning geometry. This system provides high frame rate of ~1 Hz. We demonstrate the performance of this system using phantom imaging studies.
Vesicoureteral reflux is the abnormal flow of urine from your bladder back up the tubes (ureters) that connect your kidneys to your bladder. Normally, urine flows only down from your kidneys to your bladder. Vesicoureteral reflux is usually diagnosed in infants and children. The disorder increases the risk of urinary tract infections, which, if left untreated, can lead to kidney damage. X-Ray cystography is used currently to diagnose this condition which uses ionising radiation, making it harmful for patients. In this work we demonstrate the feasibility of imaging the urinary bladder using a handheld clinical ultrasound and photoacoustic dual modal imaging system in small animals (rats). Additionally, we demonstrate imaging vesicoureteral reflux using bladder mimicking phantoms. Urinary bladder imaging is done with the help of contrast agents like black ink and gold nanoparticles which have high optical absorption at 1064 nm. Imaging up to 2 cm was demonstrated with this system. Imaging was done at a framerate of 5 frames per second.
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