Radiological and radionuclide investigation of malignant otitis externa.

This study looks at case series of malignant otitis externa, outlines detailed structural (radiological) and functional (radionuclide) investigations, and discusses their utility in the initial diagnosis, patient management and follow up of this condition. Patients were investigated by computerized tomography (CT), magnetic resonance imaging (MRI), two-phase planar and single-photon emission tomography (SPECT), technetium-99m methylenediphosphonate bone scans, gallium-67 planar and SPECT scans, and indium-111 or technetium-99m labelled WBC planar and SPECT scintigraphy. We discuss example case reports with the various radiological and scintigraphic findings and outline a protocol for rational investigation. It is concluded that CT and/or MRI should be supported by routine SPECT bone imaging for initial diagnosis of malignant otitis externa. Routine SPECT bone imaging further supplemented by gallium scintigraphy should be the investigation of choice in the follow up of these cases for assessing response to treatment and disease recurrence.

Clinical evaluation of technetium-99m infecton for the localisation of bacterial infection.

The aim of the study was to distinguish infection from inflammation in patients with suspected infection using technetium-99m Infecton. Ninety-nine patients (102 studies) referred for infection evaluation underwent imaging with 400 MBq 99mTc-Infecton at 1 and 4 h. Most patients had appropriate microbiological tests and about half (56) had radiolabelled white cell scans as well. No adverse effects were noted in any patient. The clinical efficacy of 99mTc-Infecton depended in part on whether imaging was undertaken during antibiotic therapy for infection or not. In consultation with the microbiologist, 5-14 days of appropriate and successful antibiotic therapy was considered adequate to classify some results as true-negatives. The figures for sensitivity and specificity of 99mTc-Infecton for active or unsuccessfully treated infection were 83% and 91% respectively. It is concluded that 99mTc-Infecton imaging contributed to the differential diagnosis of inflammation. It is being used as the first imaging modality when bacterial infection is suspected.

Detection of early asymptomatic esophageal dysfunction in systemic sclerosis using a new scintigraphic grading method.

OBJECTIVE: To screen patients with systemic sclerosis (SSc) for esophageal disease and to demonstrate a new system of grading dysmotility; to determine the relationship between the symptom of dysphagia and the degree of hypomotility shown by scintigraphy. METHODS: 301 patients with SSc were studied by esophageal scintigraphy using a semisolid orally ingested bolus to detect esophageal dysfunction and gastroesophageal reflux. A new system of grading was used to quantitate the degree of dysfunction, ranging from grade 0 (normal) to grade 4 (severe abnormality). RESULTS: 246 (82%) patients in the study population had evidence of esophageal hypomotility. Gastroesophageal reflux was noted in 83 (28%) patient. The largest number of patients (33%) were found to have grade 2 abnormalities. The number of patients with reflux decreased with increasing severity of grade, from grade 2 to grade 4 (35 to 13%). A retrospective study of the symptoms of 50 of the total study population showed that increasing severity of grade correlated with increasing mean duration of SSc. There was no significant relationship between disease subset and the presence or severity of esophageal hypomotility. 60% of patients in grades 1 and 2 (i.e. with observed dysmotility shown on scintigraphy) had no symptoms of dysphagia. In the more severe grades (scan grades 3 and 4), symptoms of dysphagia correlated with increase in grade. CONCLUSION: Symptoms may be unreliable in judging the presence of extent of esophageal disease in SSc. Esophageal scintigraphy is a useful noninvasive screening test for the detection of asymptomatic disease. The new grading system provides information that rapidly identifies the stage of esophageal disease and gives comparative data for followup and interventional studies.

Comparison of 99mTc infecton imaging with radiolabelled white-cell imaging in the evaluation of bacterial infection.

BACKGROUND: Bacterial infection can pose a substantial diagnostic dilemma. Techniques involving radiolabelled leucocytes can pinpoint the site of inflammation. However, previous radiolabelling techniques have failed to distinguish between bacterial-mediated infection and non-bacterial inflammation. To overcome this difficulty, we have studied a radiopharmaceutical, technetium-99m (99mTc) Infecton, which is based on the antibiotic ciprofloxacin. METHODS: We used this agent to image bacterial infection in 56 patients (one twice) with known or suspected sites of infection. We then compared the imaging results of these patients with those from a radiolabelled leucocyte study. FINDINGS: The concordance rate was 68% (39 out of 57 images). In 18 discordant results 99mTc Infecton was correctly positive in 8 out of 9 positive studies and correctly negative in 4 out of 9 negative studies. 4 out of 5 of the falsely negative studies were in patients who had taken antibiotics for over 7 days. We found that 99mTc Infecton gave better imaging results than radiolabelled leucocytes. Comparison between 99mTc Infecton and leucocyte imaging gave sensitivities of 84% and 81%, and specificities of 96% and 77%, respectively. INTERPRETATION: We believe that the specificity 99mTc Infecton confers for bacterial infection and its ease of administration are the main advantages of this new agent.

Tumour imaging.

This review looks at the nuclear medicine scanning techniques that are available for tumour imaging. It aims to promote an understanding of the specific value of this imaging modality, and thereby help to conserve resources, save time, and assist clinicians in providing optimal care.

Predictive value of captopril transit renography in essential hypertension and diabetic nephropathy.

Captopril renography was utilized to assess the presence of angiotensin II dependent renovascular dysfunction in (1) 28 patients with mild to moderate essential hypertension (EH) with unimpaired renal function, and (2) 25 hypertensive patients with diabetic nephropathy (HDN). These studies were classified according to the diagnostic criteria outlined by the Working Party on Diagnostic Criteria of Renovascular Hypertension with Captopril Renography and the mean parenchymal transit time (MPTT) was used as an index for detecting the presence of angiotensin II dependent renal haemodynamic change. Patients with EH showed non-significant or non-specific alterations in the MPTT. Four patients in the HDN group showed a significant prolongation of MPTT in the presence of renin-angiotensin-aldosterone activation due to renal artery stenosis, and the other patients in this group showed a significant decrease in MPTT after captopril, consistent with increased blood flow and improved tubular transport function in the presence of microangiopathy only. We conclude that addition of MPTT to the standard diagnostic criteria of captopril renography may be helpful in predicting the beneficial or detrimental impact of angiotensin II inhibition treatment in HDN and in limiting the test protocol in EH to one post-captopril study.

Diagnostic value of radionuclide phallography with intravenous vasodilator stress in the evaluation of arteriogenic impotence.

Arteriogenic impotence is a major cause of organic erectile dysfunction. We evaluated the diagnostic value of quantitative radionuclide phallography with intravenous pharmacological stress in screening impotent patients for penile arterial inadequacy. Using technetium-99m labelled autologous erythrocytes, dynamic scintigraphy of the penile blood pool was performed. Penile haemodynamic changes following intravenous injection of the vasodilator isoxsuprine hydrochloride were assessed by quantitation of penile blood flow and volume. Forty-seven impotent patients (11 psychogenic, 24 arteriogenic, 10 venogenic, 2 endocrine) were studied. Arteriogenic impotent patients demonstrated a lesser degree of increase in penile blood flow and volume than impotent patients with uncompromised penile arterial inflow. Quantitation of penile blood flow and volume yielded a high diagnostic accuracy (> 90%). Radionuclide phallography with intravenous vasodilator stress forms a simple and accurate method for evaluating the functional integrity of penile arterial inflow.

Captopril renal scintigraphy in patients with hypertension and chronic renal failure.

UNLABELLED: The aim of this prospective study was to determine the ability of the captopril renogram to reveal the presence of angiotensin II-dependent renovascular disorder in hypertensive patients with chronic renal failure and to assess the possibility of predicting beneficial effect of angiotensin-converting enzyme (ACE) inhibitors on renal function. METHODS: Forty-one patients were evaluated. Baseline renal scintigraphy was performed with 80 MBq of 99mTc-mercaptoacetyltriglycine (MAG3) injected intravenously. Scintigraphy was repeated within a week with 25 mg of oral captopril given 60 min prior to the test. Using the measurements outlined by the Working Party on Diagnostic Criteria of Renovascular Hypertension with Captopril Renography, the patients were categorized into high (7 patients), indeterminate (19 patients) and low (15 patients) probability for renal artery stenosis (RAS). RESULTS: In five of the seven patients with high probability, the presence of RAS was confirmed angiographically and corrective surgical procedure performed in two. In patients with GFR of 10 ml/min/1.73 m2 and/or split renal function of 10% or less, all qualitative and semiquantitative scintigraphic parameters were nonspecific. Mean parenchymal transit time of tracer was a useful parameter to predict the beneficial effect of ACE inhibition therapy in 23 patients (14 low and 9 indeterminate probability of RAS). CONCLUSION: In hypertensive patients with renal failure, captopril renal scintigraphy can be utilized to identify the presence of angiotensin II-dependent renal dysfunction and possibly help to predict the beneficial effect of ACE inhibitor therapy.

A pilot study of flaccid penile blood flow patterns in normal subjects and patients with erectile dysfunction.

Dynamic penile scintigraphy was performed using 99Tcm-labelled autologous erythrocytes in five normally potent volunteers and 22 patients with erectile dysfunction including 11 patients with psychogenic and 11 patients with vasculogenic impotence (four arteriogenic, three venogenic, three arteriogenic and venogenic, one arteriogenic and neurogenic). Penile radioactivity changes in the flaccid state were monitored by a gamma camera for 60 min after injection of the radionuclide. The penile time-activity curves of the normal controls characteristically showed secondary pulses of increased activity of variable amplitude, duration and frequency, consistent with phasic increase in penile blood pool. This normal rhythmic pattern was impaired in patients with penile arterial insufficiency whereas a blunted pattern was seen in most patients with functional impotence as well as in patients with nonarteriogenic organic impotence with a psychological overlay. This study provides new insights into the flaccid penile circulatory physiology, which may contribute to our understanding of the pathophysiology of erectile dysfunction. In arteriogenic subjects, the impaired response may be attributable to an inadequacy of penile arterial inflow as well as secondarily due to the resultant sinusoidal dysfunction subsequent to penile ultrastructural damage due to an altered nutritive environment. Increased adrenergic activity in patients with psychogenic impotence may be responsible for the observed deviation from the normal pattern.

Volume-dependent intracavernous hemodilution during pharmacologically induced penile erections.

The change in the cavernous hematocrit following induction of pharmacological erection by an intracavernous injection of papaverine hydrochloride was documented in normal controls and patients with impotence. Blood samples taken from the penile cavernosa showed a significantly lower hematocrit compared to the systemic venous blood in all normal subjects. The decrease in the cavernous hematocrit was attributable to dilution of the cavernous blood pool by the injected volume of the drug, since this was not observed in erections produced by visual sexual stimulation. It appears that a restriction of the cavernous venous outflow in response to papaverine injection causes sequestration of the diluted blood in the cavernous compartment. The degree of cavernous hemodilution was found to aid in the differential diagnosis and was especially valuable in differentiating patients with arteriogenic impotence from those with venous leakage.

The effect of intracavernosal haemodilution on the radionuclide quantification of penile vascular changes during pharmacologically induced penile erections.

Radionuclide phallography was performed using 99Tcm-labelled red blood cells in conjunction with pharmacologically induced penile erections. The radioactivity content of aliquots of systemic venous blood taken from the antecubital vein was compared with aliquots of blood withdrawn from the penile cavernosa 20 min after an intracavernosal injection of 10 micrograms prostaglandin E1. The cavernosal samples showed significantly lower counts per unit of blood compared to the systemic venous blood indicating a comparatively lower concentration of tagged red blood cells. On haematological analysis, a significant difference in the haematocrit of the two samples was also established. The fall in the cavernosal haematocrit was found to result from dilution of the cavernosal blood pool by the injected volume of the drug since larger volumes of injection produced a greater fall in the haematocrit. Restriction of the cavernosal venous outflow in response to the injection of the vasoactive drug causes sequestration of the diluted blood in the cavernosal compartment. This factor might affect the quantification of penile blood volume using radiotracer methods.