Technetium-99m hexamethylpropyleneamineoxime labelled leucocyte scanning in the initial diagnosis of Crohn's disease.

The technetium hexamethylpropyleneamineoxime labelled white cell scan (WCS) is not widely used as a screening test for Crohn's disease primarily because, though sensitive, it is perceived as being insufficiently specific. A series of 42 patients screened for Crohn's disease by this method was analysed retrospectively. The sensitivity was 100% and specificity 91%. This performance was maintained in a subgroup of these patients with very low prevalence of disease. If appropriate criteria for interpretation are used the WCS is a specific as well as a sensitive screening test for Crohn's disease.

Oral [111In]DTPA scintigraphic assessment of colonic transit in constipated subjects.

Patterns of colonic transit were assessed by a simple radioisotopic technique using 3.7 MBq of orally administered [111In]DTPA in 16 control subjects and 37 patients with intractable constipation. Normal subjects showed rapid diffuse spread of isotope through the colon resulting in low activity in all regions of interest (ROI). Activity was lost to feces at 24 hr and was virtually complete by 72 hr (median 94%, range 71-100%). Five constipated patients showed normal transit. Those with colonic inertia (N = 26) showed a significantly slowed geometric center of isotope compared to controls (P < 0.001), falling below the normal range at 48 hr. Percentage activity curves showed the major site of isotope hold-up to be in the transverse colon and splenic flexure. Other constipated patients (N = 6) showed late delay of the geometric center of isotope and accumulation of activity in the descending and rectosigmoid colon, compared to controls, at 96 hr. Oral [111In]DTPA colonic scintigraphy is a useful clinical test in the investigation of constipation.

The role of indium-labelled leukocyte imaging in pyrexia of unknown origin.

Indium-111-labeled white blood cell scanning is often used in the investigation of pyrexia of unknown origin (PUO) to locate an otherwise occult source of sepsis. From a series of 166 white blood cell studies performed for sepsis, 28 cases of true PUO were identified and reviewed. The sensitivity was 60% and specificity 70%, with a positive predictive value of 38% and negative predictive value of 90%. Only 11% of studies revealed a pyogenic cause for PUO. These results are discussed and the potential role of gallium scanning in PUO is raised.

Dynamic scanning defines a colonic defect in severe idiopathic constipation.

A technique is described in which a chemical stimulus applied to the mucosa of the right colon is used to assess colonic motor function. Peroral intubation of the right colon was achieved using a fine polyvinylchloride (PVC) tube. Bisacodyl was used to initiate colonic motor activity, and colonic transit was monitored using 99mTc-DPTA and a gamma camera. In normal subjects there was rapid movement of the radiopharmaceutical from the right colon to the rectum. In patients with severe idiopathic constipation, a spectrum of colonic abnormality was observed from slow transit involving the rectum and sigmoid only to slow transit involving the whole colon. The hepatic flexure to rectum transit time for the 'head of the isotope column' in normals ranged from 1-10 minutes (mean 5.3 minutes), whereas in patients the transit time was 14-25 minutes in four patients and radioisotope did not reach the rectum by two hours in three other patients (controls v patients, p less than 0.01). Patients also showed relatively impaired transport of the isotope 'mass'. This technique has shown that the normal colon is capable of rapid effective transport in response to a standard stimulus, and that patients with severe idiopathic constipation have a definable colonic motor disorder.

Regional evaluation of the left ventricular wall motion by radionuclide ventriculography.

ECG gated radionuclide ventriculography was performed in 85 patients with heart disease. From the analysis of time activity curves of each pixel, sets of parametric scans were displayed. Of 496 parametric scans, 192 were normal and 304 showed wall motion abnormalities. There was good correlation between the individual parametric scans (r greater than or equal to 0.815) and between parametric scans and contrast ventriculograms (r greater than or equal to 0.631) in the occurrence and extent of regional wall motion abnormalities. The highest sensitivity was revealed by the peak filling rate (relaxation velocity) scan. The best specificity was shown by scans using the amplitude and phase of the first Fourier element. Good results were obtained by a combination of four parametric images. The ability of the phase scan to detect local dyskinesis may be better than that of the contrast ventriculogram. Changes in parametric scans were related to, but preceded, impairment of left ventricular function (r greater than or equal to 0.513), It is concluded that parametric scans provide a reliable, objective and non-invasive method for regional evaluation of left ventricular function, of great use in the diagnosis of local wall motion abnormalities and their effect on the heart performance.

Isotope bone imaging in suspected scaphoid trauma.

The unreliability of radiological examination in excluding or confirming a suspected scaphoid fracture after carpal trauma is a well-recognised diagnostic problem. This paper explores the role of isotope bone imaging (IBI) in the early identification of carpal bone injury. Abnormal generalized uptake of activity may be seen within the carpus, possibly as a consequence of diffuse soft tissue injury, particularly if imaging is performed within 48 hours of trauma. A focal area of increased uptake related to one carpal bone is suggestive of fracture though the part which ligamentous injury, localized periosteal reaction or incomplete cortical infarction may play in the production of such radionuclide appearances is uncertain. Ninety-nine patients with suspected recent scaphoid fracture but no demonstrable abnormality on radiological examination were subjected to IBI, using 555 MBq (15 mCi) of 99Tcm methylene diphosphonate. Abnormal focal increased uptake (AFIU) was found in 47 patients, this being localized to the scaphoid bone in 26. Of these 47 cases, 19 (42%) showed subsequent radiological evidence of fracture. The results of IBI, in our experience, can only be reliably interpreted if imaging is performed at least 48 hours after injury, though in cases of fracture AFIU may persist for several years. Using this technique, the possibility of fracture can be confidently excluded in that group of patients who show no AFIU. In selected cases of carpal trauma, IBI provides a satisfactory alternative means of identifying the presence and site of localized injury within the carpus and may be used to confidently exclude those patients with non-osseous symptomatology.

left ventricular segmental wall motion-a comparison between equilibrium radionuclide angiography and contrast angiography.

The qualitative assessement of left ventricular wall motion using a four-point scale has been compared between left ventricular contrast angiography and equilibrium radionuclide angiography in the 30 degrees right anterior oblique projection. Analysis was carried out for five segments of the left ventricle. Four modes of analysis of equilibrium radionuclide angiography were compared and the reproducibility assessed. Overall accuracy of equilibrium radionuclide angiography compared to contrast angiography was greater than 82% to within one degree of motion. One method using a cine display, averaged 97%. We suggest that equilibrium radionuclide angiography using the cine display is the non-invasive investigation of choice in the screening of patients with suspected regional wall motion abnormalities.

Assessment of progression of secondary bone lesions following cancer of the breast or prostate using serial radionuclide imaging.

A serial study on 32 patients with bone metastases following cancer of the breast or prostate was performed over three years. Up to ten sets of images (average of four) per patient were obtained during this period using 99Tcm methylene diphosphonate as the radiopharmaceutical. Ninety-three paired serial images of individual lesions were qualitatively assessed for change by three physicians in nuclear medicine and the results were compared with the quantitative results from computer analysis. The reproducibility of the quantitative approach was determined by the analysis of 20 paired lesions by three physicists. It was found that quantitative changes in uptake of less than 20% between images were generally not detected by the medical observers; a change of 41% had only a 95% probability of being identified as change by the physicians. Although much more reproducible in determining changes in individual lesions, the quantitative approach was found to be inferior to the qualitative assessment of overall change in the majority of cases which involve multiple lesions. The basic assumption that uptake varies proportionally with progression of the bone lesion is discussed an is considered in some instances to be untenable. The conclusion is drawn that the determination of progression from changes of uptake in longstanding lesions is uncertain and is subsidiary in importance to the detection of new lesions.

The effect of various background protocols on the measurement of left ventricular ejection fraction in equilibrium radionuclide angiography.

Four methods of calculating left ventricular ejection fraction from equilibrium radionuclide angiography have been assessed for inter-observer variability and compared to single-plane contrast cineangiography. The superiority of data-processing methods which use a left ventricular region of interest which follows the changing size of the left ventricle into systole is demonstrated. A simple method of correcting for background is suggested as an alternative for those centres not possessing the necessary software for methods involving a changing region of interest.

Gall-bladder sensitivity to cholecystokinin in patients with gall stones.

Gall-bladder sensitivity to cholecystokinin (CCK) was determined by dynamic cholescintigraphy in 18 patients with radiolucent gall stones and 18 matched controls during an infusion of CCK in which the rate of infusion was increased. In 10 of the matched pairs the patient was more sensitive than the control, in one the control was more sensitive, and in seven no difference was detected (p = 0.012). It is concluded that patients with cholesterol gall stones have increased gall-bladder sensitivity to CCK, and that this may be important in the pathogenesis of this disease.