Noninvasive assessment of coronary plaque burden using multislice computed tomography

We performed coronary plaque imaging with 16-row multislice computed tomography in 85 patients who had stable angina pectoris and a high pretest likelihood of having coronary plaque to evaluate plaque burden, i.e., extent (number of diseased coronary segments) and size (small vs large) of plaque. We also assessed type of plaque (calcified, noncalcified, or mixed) and its anatomic distribution. Of 85 patients included, 78 (92%) had fully evaluable multislice computed tomograms that allowed assessment of coronary plaque burden, including major and side branches (>or=2 mm), yielding a total of 855 segments. These 78 patients (92% men; mean age +/- SD 58 +/- 11.5 years) were in sinus rhythm, with heart rates of <70 beats/min (spontaneous or induced by beta blocker). Plaque was detected in 57% of all segments (487 of 855). The mean number of segments with plaque per patient +/- SD was 6.2 +/- 3.9. Plaque was classified as large in 33% of segments and small in 67%. Overall, 65% of plaques were calcified, 24% were noncalcified, and 11% were mixed. Plaques were predominantly located in the proximal and middle segments of the main coronary vessels.     

Computed tomography coronary angiography accuracy in women and men at low to intermediate risk of coronary artery disease

Objectives

To investigate the diagnostic accuracy of CT coronary angiography (CTCA) in women at low to intermediate pre-test probability of coronary artery disease (CAD) compared with men.

Methods

In this retrospective study we included symptomatic patients with low to intermediate risk who underwent both invasive coronary angiography and CTCA. Exclusion criteria were previous revascularisation or myocardial infarction. The pre-test probability of CAD was estimated using the Duke risk score. Thresholds of less than 30?% and 30–90?% were used for determining low and intermediate risk, respectively. The diagnostic accuracy of CTCA in detecting obstructive CAD (≥50?% lumen diameter narrowing) was calculated on patient level. P?<?0.05 was considered significant.

Results

A total of 570 patients (46?% women [262/570]) were included and stratified as low (women 73?% [80/109]) and intermediate risk (women 39?% [182/461]). Sensitivity, specificity, PPV and NPV were not significantly different in and between women and men at low and intermediate risk. For women vs. men at low risk they were 97?% vs. 100?%, 79?% vs. 90?%, 80?% vs. 80?% and 97?% vs. 100?%, respectively. For intermediate risk they were 99?% vs. 99?%, 72?% vs. 83?%, 88?% vs. 93?% and 98?% vs. 99?%, respectively.

Conclusion

CTCA has similar diagnostic accuracy in women and men at low and intermediate risk.

Key Points

? Coronary artery disease (CAD) is increasingly investigated by computed tomography angiography (CTCA). ? CAD detection or exclusion by CTCA is not different between sexes. ? CTCA diagnostic accuracy was similar between low and intermediate risk sex-specific-groups. ? CTCA rarely misses obstructive CAD in low–intermediate risk women and men. ? CAD yield by invasive coronary angiography after positive CTCA is similar between sex-risk-specific groups.     

Adenylate cyclase and guanylate cyclase activity in normal and leukemic human lymphocytes

Adenylate cyclase (AC) and guanylate cyclase (GC) activities were studied in normal B-enriched and T-enriched lymphocytes, in lymphocytes of children with acute lymphocytic leukemia (ALL), and in lymphocytes of adults with chronic lymphocytic leukemia (CLL). AC activity was greater in normal B than T lymphocytes (215 pmole/min/mg protein versus 80 pmole in the membrane-enriched fraction) and i both increased greatly after stimulation with isoproterenol and more so with prostaglandins E and F2 alpha. In leukemic lymphocytes, AC showed depressed activity (20 pmole in ALL cells and 55 pmole in CLL cells) and was less sensitive to hormonal stimulation: this loss of sensitivity occurred to a greater extent in ALL than in CLL lymphocytes. GC activity was greater in normal T than B cells (in membrane-enriched fraction: 10.2 pmole versus 5.3 pmole). It increased little with isoproterenol and prostaglandins stimulation, and much more with sodium azide and dehydroascorbic acid stimulation. GC activity was increased in both types of leukemic lymphocytes (23 pmole for ALL cells and 18 pmole for CLL cells) and was insensitive to stimulation. Possible derangement of cyclase and cyclic nucleotide regulation in leukemic cells is suggested.     

Three-dimensional coronary anatomy in contrast-enhanced multislice computed tomography

A number of three-dimensional imaging modalities, such as magnetic resonance imaging, electron beam computed tomography, ultrasonography, and multislice computed tomography have been introduced in cardiovascular medicine. One of the most recently developed techniques, multislice computed tomographic coronary angiography, allows assessment of the small coronary vessels. The entire heart is scanned within a single breathhold and contrast-enhanced images are reconstructed through retrospective electrocardiographic gating. Instead of the conventional two-dimensional projection images, multislice computed tomographic data can be displayed in a three-dimensional, volume-rendered manner. This paper presents an overview of the cardiac and coronary morphology as it is imaged with contrast-enhanced multislice computed tomography. Further imaging characteristics of computed tomographic angiography are discussed.     

Is there a therapeutic role for octreotide in patients with ectopic Cushing's syndrome?

Cushing's syndrome (CS) due to ectopic ACTH secretion (EAS) has a high morbidity and mortality, because of the underlying tumor and the sequelae of severe hypercortisolemia. Therefore, rapid treatment of ectopic CS is mandatory. Scintigraphy shows that up to 80% of ectopic ACTH-producing tumors have somatostatin receptors. While this suggests that somatostatin analogs may reduce ACTH production and treat patients with EAS, the therapeutic role of these agents is still evolving. Here we demonstrate the spectrum of responses to octreotide therapy in 3 patients with EAS. Diagnostic imaging with the 111In-pentetreotide scan did not predict the therapeutic response to octreotide. Two patients with positive somatostatin receptor scintigraphy failed to respond to octreotide, while one with a negative scan reached eucortisolemia on a maintenance dose of 75 microg octreotide twice daily or octreotide LAR 30 mg per month. We conclude that octreotide is not a first line agent to control hypercortisolemia but may be a useful agent when other inhibitors of steroidogenesis fail or parenteral administration is required. Before therapy an octreotide challenge test may predict therapeutic response. Cortisol levels should be monitored regularly on somatostatin analog therapy, because of its unpredictable long-term pharmacodynamic profile.     

The ovine corticotropin-releasing hormone stimulation test and the dexamethasone suppression test in the differential diagnosis of Cushing's syndrome

We gave a standard dexamethasone suppression test and an ovine corticotropin-releasing hormone (CRH) stimulation test to 41 patients with adrenocorticotrophic hormone (ACTH)-dependent hypercortisolism to determine the efficacy of each test in the differential diagnosis of Cushing's syndrome. Twenty-nine of thirty-three patients with Cushing's disease and 0 of 8 patients with ectopic secretion of ACTH responded to the ovine CRH test with increased levels of cortisol. When a cortisol response was judged as positive for Cushing's disease, the CRH test had a diagnostic sensitivity, specificity, and accuracy of 88%, 100%, and 90%, respectively. Twenty-nine patients with Cushing's disease and 1 patient with ectopic secretion of ACTH responded to the dexamethasone suppression test. A combined-test strategy requiring negative results from both tests to exclude a diagnosis of Cushing's disease yielded superior sensitivity (100%) and diagnostic accuracy (98%). Thus, the ovine CRH test works as well as the standard dexamethasone suppression test in discriminating between Cushing's disease and ectopic ACTH secretion. The diagnostic power of each test is enhanced when the two tests are combined.     

Medical Therapy of Cushing's Disease

Surgical excision of an ACTH-producing pituitary tumor is the optimal therapy for Cushing's disease. However, medical therapy may have either a primary or adjunctive role if the patient cannot safely undergo surgery, if surgery fails, or if the tumor recurs. When medication is the only therapy, a major disadvantage is the need for lifelong therapy; in general, recurrence follows discontinuation of treatment. These compounds work through three broad mechanisms of action. Neuromodulatory compounds modulate corticotropin (ACTH) release from a pituitary tumor, steroidogenesis inhibitors reduce cortisol levels by adrenolytic activity and/or direct enzymatic inhibition and glucocorticoid antagonists block cortisol action at its receptor.In general, neuromodulatory compounds (bromocriptine, cyproheptidine, somatostatin and valproic acid) are not very effective agents for Cushing's disease. Treatment with a glucocorticoid antagonist and radiation therapy has been reported on a single patient only. Steroidogenesis inhibitors, including mitotane, metyrapone, ketoconazole, and aminoglutethimide, are the agents of choice for medical therapy of Cushing's disease. In general, ketoconazole is the best tolerated of these agents and is effective as monotherapy in about 70% of patients. Mitotane and metyrapone may be effective as single agents, while aminoglutethimide generally must be given in combination. The intravenously-administered etomidate may used when patients cannot take medications by mouth.     

Diagnostic accuracy of intra-abdominal fluid collection characterization in the era of multidetector computed tomography

The purpose of this study was to test the hypothesis that with improved technology, the presence of abscess in a postoperative fluid collection may be prospectively made. This is an Institutional Review Board-approved, Health Insurance Portability and Accountability Act-compliant retrospective review of computed tomography (CT)-guided intra-abdominal fluid collection drainages. The diagnostic CT scans of 95 consecutive patients performed on 16- and 64-multidetector CT (MDCT) were reviewed by four readers with varying abdominal imaging expertise. Readers were asked to determine fluid content, to document whether infection was present, and to rate reader confidence for infection. A fifth radiologist reviewed the collections for imaging characteristics. The gold standard for presence of infection was microbiological Gram stain and culture. The logistic regression model showed that both fluid collections containing gas or high attenuation fluid (average CT density 20 or greater Hounsfield units) are significant predictors of infection (P = 0.001). The average sensitivity over the four readers for determining presence of infection was 83.4 per cent and specificity was 39.3 per cent. Even in the era of MDCT, the ability to predict whether or not a fluid collection is infected or not, based on imaging findings alone, is limited. Presence of gas is a strong indicator of infection, but no imaging finding is characteristic of a sterile fluid collection.