Motion detection and correction using multi-rotation 180 degrees single-photon emission tomography for thallium myocardial imaging.

Patient and organ motion is a potentially limiting factor in gamma camera single-photon emission tomography (SPET) imaging, as highlighted in stress thallium myocardial SPET, where the heart may exhibit a systematic axial motion (cardiac creep) following stress. Multi-rotation SPET has previously been described as a means of obtaining better raw data for motion detection and correction. This study describes the validation of a computerised motion detection algorithm applied to multi-rotation SPET, and reports measured motions in thallium myocardial stress SPET studies from a single-headed gamma camera. Forty-two patients underwent pharmacological stress (dipyridamole) with leg raising, with injection of 75 MBq thallium-201 and imaging after a 10-min delay to detect or evaluate coronary artery disease. Multi-rotation gamma camera SPET was performed with a single-headed gamma camera, with five sequential rapid (4.5 min) continuous SPET mode rotations over 180 degrees. A one-dimensional cross-correlation alignment technique was applied to the projection images to perform motion detection and correction in the axial direction prior to combining the five data sets for tomographic reconstruction. Validation of the cross-correlation alignment analysis was carried out by performing imaging with measured whole-body axial motions in nine subjects, and by reproducibility measurements on multi-rotation data sets. The effect of the applied motion correction was evaluated by calculating mean differences between image pairs before and after shifting, and the general reliability of the automatic motion detection was checked to within one pixel by visual assessment of 160 image pairs. Validation measurements of the cross-correlation technique gave a mean absolute error of 1.5+/-0.4 mm (0.24+/-0.06pixels) with a maximum error of 3.7 mm (0.6 pixels). In 40 subjects undergoing pharmacological stress 201Tl myocardial SPET imaging, the mean cardiac axial creep movement was calculated as 3.1+/-0.7 mm (0. 49+/-0.11 pixels), with 13 out of 40 (32%) having a calculated motion of 1 pixel (6.3 mm) or more. The automatic image shift was visually judged to be within 1 pixel in all 160 image pair analyses, and the mean pixel value difference between image pairs was reduced following image shifting. It is concluded that multi-rotation 180 degrees SPET imaging provides raw data which allow objective and accurate motion detection of cardiac motion in thallium stress myocardial imaging, whilst the one-dimensional cross-correlation technique demonstrates adequate accuracy and reliability to be applied as an automatic motion screening technique on these data.

Dipyridamole stress thallium-201 perfusion abnormalities in patients with hypertrophic cardiomyopathy. Relationship to clinical presentation and outcome.

AIMS: Thallium-201 perfusion abnormalities are common in patients with hypertrophic cardiomyopathy and may be associated with an adverse prognosis in the young. The aim of this study was to prospectively determine the relationship between thallium-201 defects during dipyridamole stress to clinical presentation and outcome in a large consecutive series of patients with hypertrophic cardiomyopathy. METHODS/RESULTS: Thallium-201 single photon computed tomography was performed in 216 patients with hypertrophic cardiomyopathy during dipyridamole stress (0.5 mg. kg-1). Fixed perfusion defects occurred in 25%, and reversible defects in 22%. A combination of defects was present in 7%. Fixed defects were associated with: a history of syncope (17 of 46 with, vs 36 of 170 without syncope, P = 0.03); larger left ventricular end-diastolic (46.9 +/- 7.4 mm vs 43.3 +/- 6.4 mm; P = 0.001) and end-systolic dimension (30.2 +/- 8.4 mm vs 24.5 +/- 5.9 mm, P < 0.0001); increased left atrial diameter (46.1 +/- 8.1 mm vs 40.5 +/- 7.7 mm, P < 0.0001); lower fractional shortening (35.9 +/- 10.4% vs 43.8 +/- 8.6%, P < 0.0001): and lower maximal exercise oxygen consumption (24.2 +/- 8.1 ml. min-1. kg-1 vs 29.4 +/- 8.8 ml. min-1. kg-1, P < 0.0003). Reversible defects did not correlate with symptomatic status, but were associated with: larger left atrial dimensions (44.5 +/- 8.1 mm vs 41.0 +/- 8.0 mm; P = 0.009) and greater maximal left ventricular wall thickness (24.0 +/- 7.0 mm vs 20.6 +/- 7.0 mm, P = 0.003). The mean follow up time was 41 +/- 21 months, range 0.6-124. There was no association between any thallium-201 abnormality and disease related death in young or adult patients. CONCLUSION: The present study shows that fixed thallium-201 perfusion defects detected during dipyridamole stress in patients with hypertrophic cardiomyopathy are associated with syncope, larger left ventricular cavity dimensions and reduced exercise capacity. Although the event rate was relatively small, there was no evidence for an association between thallium-201 defects and survival.

Regional thallium-201 washout and myocardial hypertrophy in hypertrophic cardiomyopathy and its relation to exertional chest pain.

The mechanism of exertional chest pain in hypertrophic cardiomyopathy is uncertain, but may relate to myocardial ischemia. To study the mechanism of exertional chest pain in hypertrophic cardiomyopathy, dipyridamole-stress thallium-201 single-photon emission computed tomography was performed in 82 consecutive patients, and the 3-hour washout of thallium in relation to the tomographic image, regional wall thickness on echocardiography, and other clinical findings was analyzed. There was a weak inverse correlation of regional washout and wall thickness in 298 analyzed quadrant areas (r = -0.29; p = 0.0001). Twenty-five patients (31%) had history of exertional chest pain, and showed a significantly lower total washout and greater maximal left ventricular wall thickness than did those without chest pain (32 +/- 10% vs 37 +/- 9% [p = 0.03], and 27 +/- 7 vs 23 +/- 7 mm [p = 0.03], respectively). Even in mildly and nonhypertrophied areas, patients with chest pain had a significantly lower regional washout than did those without pain (33 +/- 10% vs 38 +/- 9%; p = 0.02), despite similar left ventricular wall thickness (12 +/- 2 vs 11 +/- 3 mm; p = NS). Reduced washout was strongly associated with exertional chest pain and was observed in myocardial regions that had normal as well as increased thickness, which indicates that this abnormality of thallium kinetics is a function of the disease process and not the magnitude of left ventricular hypertrophy.

Abnormal lymph drainage in patients with chronic venous leg ulcers.

BACKGROUND: Edema often occurs in association with venous leg ulcers. OBJECTIVE: Our purpose was to assess lymphatic function in the legs of patients with venous leg ulcers. METHODS: Quantitative lymphoscintigraphy was performed in 22 normal control subjects, 32 patients with venous leg ulcers, and 7 patients with varicose veins only. RESULTS: Lymph drainage declined with age in the normal controls (r = -0.57; p = 0.0001). Lymphatic function was reduced in the ulcerated legs compared with normal limbs (age < 65 years; p < 0.0001) and in edematous legs compared with nonedematous legs (age > 65 years; ulcerated legs, p = 0.016; nonulcerated legs, p = 0.021). Lymph drainage was lower in the legs of patients with varicose veins only (p = 0.004). CONCLUSION: Impaired lymphatic function is associated with both venous leg ulcers and chronic venous hypertension.

Investigation of the swollen limb with isotope lymphography.

The usefulness of isotope lymphography was evaluated in patients with chronic lower leg swelling. Forty patients (15 male, 25 female, age range 5 months-67 years) were assigned one of six clinical diagnoses based on clinical assessments, venography and lymphography. All the patients and seven normal controls were examined with bilateral isotope lymphography involving subcutaneous injection of 0.15 ml 99mTc-antimony sulphide colloid into the first web space of each foot. The percentage uptake of isotope-colloid in the inguinal lymph nodes at 1 and 2 h was equated with lymphatic function. Highly significant (P = 0.0001) differences existed between the different clinical groups and isotope lymphography discriminated well between oedema of lymphatic and non-lymphatic origin. Isotope lymphography appears to be a safe and useful test of lymphatic function.

Fecal leukocytosis, indium-111-labelled autologous polymorphonuclear leukocyte abdominal scanning, and quantitative fecal indium-111 excretion in acute gastroenteritis and enteropathogen carriage.

Abdominal scintiscans were performed and three-day fecal indium-111 radioactivity measured, following injection of indium-111-labeled polymorphonuclear leukocytes, in patients with acute gastroenteritis, enteropathogen carriage, exacerbations of chronic inflammatory bowel disease, and patients without gastrointestinal symptoms. The colon was more commonly inflamed than the small intestine in acute gastroenteritis. Fecal indium-111 radioactivity excretion was elevated in gastroenteritis and in chronic inflammatory bowel disease. The magnitude of the intestinal inflammatory response, as measured by fecal indium-111 excretion, is equivalent in acute gastroenteritis caused by a defined enteropathogen and exacerbations of chronic inflammatory bowel disease. All patients with microscopically detected fecal leukocytosis gave positive intestinal scintiscans, whereas negative scans were obtained on patients without fecal leukocytosis. The results of this study suggest that indium-111-labeled polymorphonuclear leukocytes can be used to study pathophysiology of the enteric inflammatory response in acute infectious gastroenteritis.