Scintigraphic assessment of distal extremity perfusion in 17 patients

Case report: Evaluation of hindlimb ischemia using 18F-fluorodeoxyglucose positron emission tomography in a cat with cardiogenic arterial thromboembolism

A 12-year-old castrated male domestic shorthair cat weighing 6.7 kg presented with acute hindlimb paralysis and tachypnea. The femoral pulse was absent bilaterally. Thoracic radiography showed finding compatible with cardiogenic pulmonary edema. Echocardiography revealed hypertrophic cardiomyopathy phenotype and a spontaneous echocardiographic contrast in the left atrium, suggesting cardiogenic arterial thromboembolism. Oxygen supplementation, diuretics, and antithrombotic and thrombolytic agents were also administered. However, hindlimb motor function was not restored. Severely increased aspartate aminotransferase and creatinine phosphokinase, as well as neutropenia with a degenerative left shift were identified, and amputation was considered to prevent sepsis caused by necrosis of the ischemic tissues. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography was performed to evaluate the metabolic activity of the muscle tissues and determine the level of amputation. There was no 18F-FDG uptake in the extremities of either the hind limbs or the caudal parts of the bilateral femoral muscle mass, suggesting a loss of metabolic activity in the area. Considering the wide affected area, a decreased quality of life was predicted postoperatively, and the cat was euthanized at the owner's request. Postmortem muscle biopsy confirmed weak atrophy of the left femoral muscle and prominent atrophy of the right calf. This case report describes the use of 18F-FDG PET in a cat with ischemia caused by cardiogenic arterial thromboembolism.

Orthopedic Diagnostic Imaging in Exotic Pets

Orthopedic diseases are a common problem in exotic pets. Diagnostic imaging modalities are more accessible and available in exotic animal veterinary medicine; the higher standards of care of the veterinary profession have progressed toward an increased offer of advanced imaging modalities. The literature on the use of diagnostic imaging modalities in orthopedic disease of exotic pets is scarce. This article discusses when to use the different diagnostic imaging techniques and reviews the imaging findings usually found in the most common orthopedic diseases in small mammal, avian, and reptile exotic pet species using different imaging modalities, especially radiography and computed tomography.

Limb amputation and prosthesis

Limb amputation is an alternative to euthanasia when catastrophic injury prevents successful restoration of the limb or when cost is an issue. Proximal limb disarticulation for amputation is preferred if a prosthesis is not considered. Distal amputations are needed to accommodate exoskeletal prosthesis. This article reviews the considerations and describes techniques for this surgery.

Comparison of the diagnostic performances of two protocols of hand perfusion scintigraphy for Raynaud's phenomenon

OBJECTIVE

The aim of this study was to compare the diagnostic performances of two hand perfusion scintigraphy protocols for diagnosing Raynaud's phenomenon (RP).

METHODS

We enrolled 130 patients who underwent hand perfusion scintigraphy for suspected RP and 40 normal controls. Of these, 66 patients (group A) and 25 normal controls underwent 99mTc-methylene diphosphonate hand perfusion scintigraphy without one-hand chilling, and the finger-to-palm ratio (FPR) was calculated. The remaining 64 patients (group B) and 15 normal controls underwent 99mTc-methylene diphosphonate hand perfusion scintigraphy with one-hand chilling, and three parameters (the chilled-to-ambient hand ratios of the first peak height, initial slope, and blood pool uptake) were calculated.

RESULTS

Forty-eight and 47 patients were clinically diagnosed with RP in groups A and B, respectively. In group A, patients with RP had significantly lower FPRs compared with those without RP, and the receiver operating characteristic curve analysis showed that an FPR of 0.51 was the best cutoff value for diagnosing RP, with a sensitivity of 63% and a specificity of 83%. In group B, the three aforementioned parameters differed significantly (lower or higher) between patients with and without RP. The receiver operating characteristic curve analysis provided highly sensitive and specific results for all three parameters. The initial slope ratio showed the highest sensitivity of 87% and a specificity of 88% when using cutoff values of 0.78 and 1.25.

CONCLUSION

Although both protocols for hand perfusion scintigraphy showed high specificity for diagnosing RP, the protocol with one-hand chilling showed higher diagnostic ability compared with that without one-hand chilling.

Quantitative assessment of therapeutic effects in the critically ischemic limb using (99m)Tc-diethylene-triamine-pentaacetic acid human serum albumin

PURPOSE

To investigate the reliability and limitations of a new radioisotope method using (99m)Tc-diethylenetriamine-pentaacetic acid human serum albumin (Tc-99m-DTPA-HSA) and to evaluate the diagnostic ability of isotope infusion for assessing hemodynamic changes in the foot before and after treatment.

METHODS

Hemodynamic changes before and after treatment were assessed in 21 limbs with ulcer or gangrene, by analyzing changes in the time-activity curve, the uptake ratio, and the values obtained with noninvasive techniques.

RESULTS

There were significant differences between each pair of the three types of time-activity curve and their uptake counts. The uptake ratio was correlated with ankle blood pressure (ABP) and toe blood pressure (TBP), but not with transcutaneous oxygen pressure (tcPO(2)) or skin perfusion pressure (SPP). The hemodynamic change induced by pharmacotherapy was subtle, but that induced by arterial reconstruction was remarkable. Although there was not always a good correlation between the degree of hemodynamic change and the clinical outcome in limbs treated with pharmacotherapy, the hemodynamic change was quantitatively assessed.

CONCLUSION

Our study suggests that this isotope technique is a useful quantitative method to evaluate hemodynamic change from a different perspective to conventional noninvasive methods.

Decreased radiopharmaceutical uptake (photopenia) in delayed phase scintigraphic images in three horses

Decreased radiopharmaceutical uptake, photopenia, in delayed phase scintigraphic images is recognized in people but has only been reported rarely in horses. We describe three horses with septic osteitis, bone sequestrum formation, or distal limb thrombosis that had photopenia of the affected extremity. Photopenia may indicate the presence of ischemia and can be used to facilitate clinical decision making and prognosis assessment

Feline arterial thromboembolism: an update

ATE remains a devastating complication of cardiac disease. Despite some improvements in our understanding of the underlying causes and clinical features of this disease, short-term management remains a challenge, and mortality is high. Long-term mortality is primarily attributable to the severe underlying cardiac disease. Many questions remain to be answered regarding the ideal management approach for feline ATE. The authors' preferred diagnostic and therapeutic approaches for these difficult patients are detailed in Box. 1.

Bone scintigraphy in the investigation of occult lameness in the dog

99mTechnetium methylene diphosphonate (99mTc-MDP) scintigraphy was performed in 14 dogs of different breeds after clinical lameness examination, radiography and synovial fluid analysis failed to localise lameness to a specific area of pain. The scintigraphic protocol included an intravenous injection of 17 MBq 99mTc-MDP/kg bodyweight and vascular, soft tissue and bone phase scans in standardised positions with a low-energy all-purpose collimator. Confirmation of diagnosis was achieved in nine dogs by arthroscopy, repeated lesion-orientated radiography, computed tomography and response to treatment. In seven cases, bone phase scans showed single elbow uptakes, in two cases unilateral limb uptake, and in one case each a single shoulder and tibia uptake; in three cases there was no increased uptake. Vascular and soft tissue phase images did not reveal additional information. Diagnosis of humeral condyle fissures, a fragmented medial coronoid process, panosteitis and arthropathy was possible in nine cases. Skeletal pathology was ruled out in three normal scintigrams. In two dogs with unilateral uptake of multiple joints, no diagnostic benefit was gained from scintigraphy. The highly sensitive and relatively specific uptake allowed localisation and characterisation or exclusion of skeletal lesions in most dogs.

Equine nuclear scintigraphy. Indications, uses, and techniques

The demand for advanced and correlative imaging methods in equine medicine is growing. Scintigraphy can provide unique information about the physiologic status of an animal that cannot be discerned by other imaging modalities.

Lameness examination in cattle

Veterinarians are often asked to examine cattle for lameness. A good history, observation of stance and stride, and physical examination are critical to the diagnosis of lameness in cattle. Methods of examination, including observation of the animal at a distance and during movement, are described. Lameness grading systems and ancillary diagnostic tests are also discussed.

Diagnostic imaging of lameness in small animals

The demand for advanced diagnostic imaging procedures such as nuclear scintigraphy, ultrasonography, computed tomography, and magnetic resonance imaging has increased dramatically over the past 10 years. Veterinarians, seeking to improve their diagnostic capabilities and clients willing to pursue "best medicine" have driven this demand, resulting in installation of advanced imaging facilities at most academic and private referral practices. Knowledge of potential benefits of various modalities will allow the veterinarian to optimize his or her use of diagnostic imaging in his or her own practice or in a referral practice.

The clinical usefulness of the fingers-to-palm ratio in different hand microcirculatory abnormalities

A non-invasive nuclear medicine technique was developed to screen patients with painful hands so as to separate patients with a normal from those with an abnormal microcirculation of the hands in different clinical conditions. Such a technique is important, as the other methods available are either subjective or rather complicated. The study population consisted of 10 healthy individuals, 23 patients with Raynaud's syndrome and 15 patients with mixed connective tissue disease (MCTD). Sixty gamma-camera images of the hands (1 s each) were recorded after a bolus injection of 99Tcm-DTPA via a dorsal foot vein. Regions of interest were drawn on the summed images around the fingers and the palmar region. The fingers-to-palm ratio was then calculated from the total counts inside these regions of interest separately for each hand. The mean fingers-to-palm ratio was 0.94+/-0.18 (0.71-1.25) for the healthy group, 0.57+/-0.22 (0.21+/-1.11) for the MCTD group and 0.40+/-0.14 (0.18-0.77) for the Raynaud's patients. Analysis of variance showed these differences to be highly significant (P < 0.001). There were also significant differences between 6 MCTD patients in an active (mean 0.48) and nine patients in an inactive (mean 0.66) clinical state (two-sample t-test: P < 0.05). There were no significant differences between the fingers-to-palm ratios of the left and right hands of the same patients (one-sample t-test). Of the 23 primary Raynaud's patients, capillary microscopic data were pathological in only eight (34%). We conclude that our method is able to differentiate between patients with normal and those with abnormal microcirculation of the hands. Although measurement of the fingers-to-palm ratio is not a specific method, it is useful both for staging and in the follow-up of patients.