Reducing Radiation Dose in Adult Head CT using Iterative Reconstruction - A Clinical Study in 177 Patients.

PURPOSE: To assess how ASIR (adaptive statistical iterative reconstruction) contributes to dose reduction and affects image quality of non-contrast cranial computed tomography (cCT). MATERIALS AND METHODS: Non-contrast emergency CT scans of the head acquired in 177 patients were evaluated. The scans were acquired and processed using four different protocols: Group A (control): 120 kV, FBP (filtered back projection) n = 71; group B1: 120 kV, scan and reconstruction performed with 20 % ASIR (blending of 20 % ASIR and 80 % FBP), n = 86; group B2: raw data from group B1 reconstructed using a blending of 40 % ASIR and 60 % FBP, n = 74; group C1: 120 kV, scan and reconstruction performed with 30 % ASIR, n = 20; group C2: raw data from group C1 reconstructed using a blending of 50 % ASIR and 50 % FBP, n = 20. The effective dose was calculated. Image quality was assessed quantitatively and qualitatively. RESULTS: Compared to group A, groups B1/2 and C1/2 showed a significantly reduced effective dose of 40.4 % and 73.3 % (p < 0.0001), respectively. Group B1 and group C1/2 also showed significantly reduced quantitative and qualitative image quality parameters. In group B2, quantitative measures were comparable to group A, and qualitative scores were lower compared to group A but higher compared to group B1. Diagnostic confidence grading showed groups B1/2 to be adequate for everyday clinical practice. Group C2 was considered acceptable for follow-up imaging of severe acute events such as bleeding or subacute stroke. CONCLUSION: Use of ASIR makes it possible to reduce radiation significantly while maintaining adequate image quality in non-contrast head CT, which may be particularly useful for younger patients in an emergency setting and in follow-up. KEY POINTS: ASIR may reduce radiation significantly while maintaining adequate image quality. cCT protocol with 20 % ASIR and 40 %ASIR/60 %FBP blending is adequate for everyday clinical use. cCT protocol with 30 % ASIR and 50 %ASIR/50 %FBP blending is adequate for follow-up imaging

Comparison of applied dose and image quality in staging CT of neuroendocrine tumor patients using standard filtered back projection and adaptive statistical iterative reconstruction.

OBJECTIVE: To investigate whether dose reduction via adaptive statistical iterative reconstruction (ASIR) affects image quality and diagnostic accuracy in neuroendocrine tumor (NET) staging. METHODS: A total of 28 NET patients were enrolled in the study. Inclusion criteria were histologically proven NET and visible tumor in abdominal computed tomography (CT). In an intraindividual study design, the patients underwent a baseline CT (filtered back projection, FBP) and follow-up CT (ASIR 40%) using matched scan parameters. Image quality was assessed subjectively using a 5-grade scoring system and objectively by determining signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNRs). Applied volume computed tomography dose index (CTDIvol) of each scan was taken from the dose report. RESULTS: ASIR 40% significantly reduced CTDIvol (10.17±3.06mGy [FBP], 6.34±2.25mGy [ASIR] (p<0.001) by 37.6% and significantly increased CNRs (complete tumor-to-liver, 2.76±1.87 [FBP], 3.2±2.32 [ASIR]) (p<0.05) (complete tumor-to-muscle, 2.74±2.67 [FBP], 4.31±4.61 [ASIR]) (p<0.05) compared to FBP. Subjective scoring revealed no significant changes for diagnostic confidence (5.0±0 [FBP], 5.0±0 [ASIR]), visibility of suspicious lesion (4.8±0.5 [FBP], 4.8±0.5 [ASIR]) and artifacts (5.0±0 [FBP], 5.0±0 [ASIR]). ASIR 40% significantly decreased scores for noise (4.3±0.6 [FBP], 4.0±0.8 [ASIR]) (p<0.05), contrast (4.4±0.6 [FBP], 4.1±0.8 [ASIR]) (p<0.001) and visibility of small structures (4.5±0.7 [FBP], 4.3±0.8 [ASIR]) (p<0.001). CONCLUSION: In clinical practice ASIR can be used to reduce radiation dose without sacrificing image quality and diagnostic confidence in staging CT of NET patients. This may be beneficial for patients with frequent follow-up and significant cumulative radiation exposure.

[Improvement of the processes around the radiology workplace : avoidance of time delays]. / Verbesserung der Prozesse rund um den radiologischen Arbeitsplatz : Vermeidung von Zeitverzögerungen.

Radiologists have been confronted with multiple new challenges in recent years. While there has been a steady increase in the number of radiological examinations and imaging material per examination, examination protocols have become more complex and highly time-consuming whereas case-based remuneration is on the decline. The identification of inefficient components in examination processes and reporting is therefore essential. Where and why do time delays occur? How can they be avoided? The following article provides a brief overview and is designed to stimulate discussion.

[Analytical characterization of palatinit (author's transl)]. / Analytische Charakterisierung von Palatinit.

The reaction product of the catalytic hydrogenation of isomaltulose (palatinose) is a mixture of alpha-D-glucopyranosido-1,6-sorbitol and alpha-D-glucopyranosido-1,6-mannitol designated palatinit. Because of its high potential as a sugar substitute methods for the identification and characterization of hydrogenation products and for the determination of palatinit as an ingredient in food preparations and biological samples are required. Several working procedures are described in full detail including thin layer and gas chromatography as well as enzymatic and chemical determinations.

Metabolism of hydrogenated palatinose, an equimolar mixture of alpha-D-glucopyranosido-1,6-sorbitol and alpha-D-glucopyranosido-1,6-mannitol.

Hydrogenated palatinose, an equimolar mixture of alpha-D-glucopyranosido-1,6-sorbitol and alpha-D-glucopyranosido-1,6-mannitol, was investigated as a potential oral sugar substitute in the following experiments in man and rat. 1. Enzymatic cleavage occurred at slow rates by maltase (alpha-glucosidase) of jejunal mucosa, liver lysosomes and yeast. 2. Part of ingested hydrogenated palatinose arrived unsplit at the caecum of the rat and underwent fermentation there; excretion in feces and urine are neglegible in man and rat. 3. Growth and maintenance of rats demonstrated 20--40 percent diminished caloric utilisation of diets containing 34.5 percent hydrogenated palatinose whereas indirect calorimetry in man showed about 50 percent caloric deficit. 4. Blood sugar did not increase in man after oral doses up to 100 g. 5. The capacity of the rat kidneys for excretion of hydrogenated palatinose and its constituents was high, symptoms of incompatibility were not observed.

[Metabolic behavior of disaccharide alcohols and related substances]. / Stoffwechselverhalten von Disaccharidalkoholen und verwandten Substanzen

The present study suggests that part of the digestion of disaccharide alcohols is due to microbic processes, primarily in the cecum. The utilization of sorbitol and palatinitol by endogenous metabolic systems seems to be restricted insofar as these substances become accessible to the intestinal flora. Interim products of the bacterial fermentation are likely to be utilized by the host organism.