Single energy metal artifact reduction performs better than virtual monoenergetic dual-energy reconstruction in CT of the equine proximal phalanx.

Metal artifacts in CT negatively impact the evaluation of surgical implants and the surrounding tissues. The aim of this prospective experimental study was to evaluate the ability of a single energy metal artifact reduction (SEMAR™, Canon) algorithm and virtual monoenergetic (VM) dual-energy CT (DECT) scanning techniques to reduce metal artifacts from stainless steel screws surgically inserted into the equine proximal phalanx. Seven acquisitions of 18 cadaver limbs were performed on a Canon Aquilion One Vision CT scanner (Helical +SEMAR, Volume +SEMAR, Standard Helical, Standard Volume and VM DECT at 135, 120, and 105 keV) and reconstructed in a bone kernel. Blinded subjective evaluation performed by three observers indicated a significant effect of acquisition in both adjacent tissues (P < 0.001) and distant tissues (P < 0.001) and the best metal artifact reduction was seen with Helical +SEMAR and Volume +SEMAR. The subjective overall preference of CT acquisition type was (1) Helical +SEMAR, (2) Volume +SEMAR, (3) VM DECT 135 keV, (4) VM DECT 120 keV, (5) VM DECT 105 keV, (6) Standard Helical, (7) Standard Volume (P < 0.001). Unblinded objective evaluation performed by one observer showed that VM DECT 120 keV, Helical +SEMAR, and Volume +SEMAR performed similarly and were objectively the best at reducing blooming artifact. Overall, the best metal artifact reduction was obtained with SEMAR, followed by VM DECT. However, VM DECT performance varies with energy level and was associated with decreased image quality in distant tissues and artifactual overcorrection of metal artifacts at high energy levels.

Role of Laparoscopy in Diagnosis and Management of Equine Colic.

Laparoscopy can be valuable in the diagnosis and treatment of specific types of colic in horses. Most commonly, it is used for horses with chronic recurrent colic for further diagnosis, such as by taking biopsies or to perform treatment. Laparoscopy is also often used for prevention of colic, for example, by closing the nephrosplenic space or epiploic foramen. There are fewer indications for laparoscopy in acute colic, though in some cases the technique can be useful for diagnosis, after which the procedure is converted to a hand-assisted laparoscopy. However, manipulation of the intestine is limited compared with an open laparotomy.

Comparison of transrectal and transabdominal transducers for use in fast localized abdominal sonography of horses presenting with colic.

Abdominal ultrasonography is valuable in the diagnosis of equine colic. Fast localized abdominal sonography of horses (FLASH) enables practitioners with limited experience to perform ultrasonography in emergency settings. However, many practitioners only possess rectal format linear array transducers (RFLT). The hypotheses are: (a) A low frequency curvilinear transducer (LFCT) and RFLT will detect free abdominal fluid and abnormal small intestinal loops with similar frequency during FLASH, and (b) there will be a difference between the transducers for detection of gastric abnormalities and nephrosplenic entrapment. The objective is to compare transcutaneous abdominal ultrasonographic detection of abnormalities in horses presenting with colic using a LFCT and RFLT. Twenty-four horses requiring FLASH for investigation of colic were enrolled. Horses that were too painful to undergo transcutaneous abdominal ultrasonographic examination were excluded. A single investigator performed FLASH on all horses using a RFLT, while one of three other clinicians simultaneously performed FLASH using a LFCT. Comparison of abnormal findings between the two transducers was performed using Chi square, Fisher's exact or Wilcoxon tests. The incidence of identification of abnormal findings was similar between the two transducers for all comparisons except the visibility of the left kidney and stomach (kidney LFCT 81.25% vs. RFLT 22.92%, stomach LFCT 87.5% vs. RFLT 62.5%). While there are limitations to using a RFLT to identify nephrosplenic entrapment of the colon and detection of the stomach, it reliably detects other common abnormalities, including peritoneal effusion, lesions of the small intestine, and changes to the wall of the large colon and cecum.

Incidence of superficial abdominal organ identification is similar using high-frequency linear (transrectal) and low-frequency curvilinear (abdominal) transducers in clinically healthy horses: A pilot study.

Abdominal organ displacement is a potentially life-threatening condition in horses. Primary care veterinarians commonly make referral decisions based on a combination of clinical and ultrasonographic findings. However, published studies describing the effects of transducer on identifying abdominal organ locations in horses are currently lacking. The objective of this prospective, methods comparison, pilot study was to compare organ identification using a high-frequency linear (transrectal) transducer and a low-frequency curvilinear (abdominal) transducer for transcutaneous abdominal ultrasonography of healthy horses. Twelve clinically normal adult horses owned by the University of Calgary were enrolled in the study. Abdominal ultrasonography was performed by four practitioners, each randomly assigned to an alternating rotation of transrectal or abdominal transducer and left or right side of a horse. Using a Chi square test or Fisher's exact test, the frequency of identification for each organ was compared between both transducers. There was no significant difference in organ identification on the right side of the abdomen. On the left side, the stomach, liver, and kidney were less likely to be detected with the transrectal transducer. Compared with a low-frequency abdominal transducer, a high-frequency linear transrectal transducer delivers images that allow for organ identification in transcutaneous ultrasonography of the equine abdomen except for the left kidney, left liver, and stomach.