Advanced Modeled Iterative Reconstruction in Low-Tube-Voltage Contrast-Enhanced Neck CT: Evaluation of Objective and Subjective Image Quality.

BACKGROUND AND PURPOSE: Dose-saving techniques in neck CT cause increased image noise that can be counteracted by iterative reconstruction. Our aim was to evaluate the image quality of advanced modeled iterative reconstruction (ADMIRE) in contrast-enhanced low-tube-voltage neck CT. MATERIALS AND METHODS: Sixty-one patients underwent 90-kV(peak) neck CT by using third-generation 192-section dual-source CT. Image series were reconstructed with standard filtered back-projection and ADMIRE strength levels 1, 3, and 5. Attenuation and noise of the sternocleidomastoid muscle, internal jugular vein, submandibular gland, tongue, subscapularis muscle, and cervical fat were measured. Signal-to-noise and contrast-to-noise ratios were calculated. Two radiologists assessed image noise, image contrast, delineation of smaller structures, and overall diagnostic acceptability. Interobserver agreement was calculated. RESULTS: Image noise was significantly reduced by using ADMIRE compared with filtered back-projection with the lowest noise observed in ADMIRE 5 (filtered back-projection, 9.4 ± 2.4 Hounsfield units [HU]; ADMIRE 1, 8.3 ± 2.8 HU; ADMIRE 3, 6.7 ± 2.0 HU; ADMIRE 5, 5.4 ± 1.7 HU; all, P < .001). Sternocleidomastoid SNR and internal jugular vein-sternocleidomastoid contrast-to-noise ratios were significantly higher for ADMIRE with the best results in ADMIRE 5 (all, P < .001). Subjective image quality and image contrast of ADMIRE 3 and 5 were consistently rated better than those for filtered back-projection and ADMIRE 1 (all, P < .001). Image noise was rated highest for ADMIRE 5 (all, P < .005). Delineation of smaller structures was voted higher in all ADMIRE strength levels compared with filtered back-projection (P < .001). Global interobserver agreement was good (0.75). CONCLUSIONS: Contrast-enhanced 90-kVp neck CT is feasible, and ADMIRE 5 shows superior objective image quality compared with filtered back-projection. ADMIRE 3 and 5 show the best subjective image quality.

Evaluation of image quality and dose reduction of 80 kVp neck computed tomography in patients with suspected peritonsillar abscess.

AIM: To evaluate neck computed tomography (CT) with a reduced tube voltage of 80 kVp in patients with suspected peritonsillar abscess (PTA) regarding objective and subjective image quality, and the potential for dose reduction. MATERIALS AND METHODS: Forty-seven patients with clinically suspected PTA were retrospectively analysed. Patients were examined using dual-source CT in dual-energy mode. The objective and subjective image quality of 80 kVp images were compared with linearly blended 120 kVp images (M_0.3; 30% of 80 kV, 70% of 140 kV spectrum). Attenuation of abscess rim enhancement, central necrosis, and several other anatomical landmarks were measured. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and rim-to-abscess CNR (raCNR) were calculated. Radiation dose was assessed as size-specific dose estimates (SSDE). Subjective image quality was assessed according to the European guidelines on quality criteria for CT. Interobserver agreement was calculated using the intraclass correlation coefficient (ICC). RESULTS: Attenuation of inflamed soft tissue (141.7 ± 16.3 versus 93.7 ± 9.3 HU, p < 0.001), CNR (9.6 ± 4.8 versus 5.6 ± 3.8, p = 0.001), raCNR (14.3 ± 5.9 versus 12.4 ± 4.4, p = 0.02), and subjective image sharpness (3.6 ± 0.6 versus 2.8 ± 0.7, p < 0.001) were significantly increased in the 80 kVp compared to 120 kVp, whereas subjective and objective image noise were significantly increased with 80 kVp acquisition (p < 0.001). Overall interobserver agreement was almost perfect (ICC, 0.87). Calculated SSDE of 80 kVp acquisition was decreased by 49.7% compared to 120 kVp (10.58 ± 0.76 versus 21.04 ± 1.43 mGy, p < 0.001). CONCLUSION: Low-tube-voltage 80 kVp neck CT provides increased enhancement of soft-tissue inflammation, CNR, raCNR, and improved abscess delineation in patients with PTA compared to standard 120 kVp acquisition while resulting in a significant reduction of radiation exposure.

Non-linear image blending improves visualization of head and neck primary squamous cell carcinoma compared to linear blending in dual-energy CT.

AIM: To compare non-linear and linear image-blending post-processing techniques in dual-energy CT (DECT) of primary head and neck squamous cell carcinoma (SCC) regarding subjective and objective image quality. MATERIALS AND METHODS: Head and neck DECT studies from 69 patients (48 male, 21 female; mean age 62.3 years) were retrospectively evaluated. All tumour lesions were histologically confirmed SCC. Linearly blended 80/140 kVp images series with varying weighting factors of 0.3 (M_0.3), 0.6 and 0.8 were compared with non-linearly blended images. Attenuation of tumour lesion, various soft-tissue structures, the internal jugular vein, and image noise were measured, tumour signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Overall image quality, delineation of tumour lesion, image sharpness, and noise level were rated individually by three radiologists using five-point Likert scales. Interobserver agreement was calculated using intraclass correlation coefficient (ICC). RESULTS: Enhancement of tumour lesions (non-linear, 137.5 ± 20.1 HU; M_0.3, 92.7 ± 14.4 HU; M_0.6, 110 ± 15.4 HU; M_0.8, 123 ± 18.2 HU), CNR (non-linear, 12 ± 8; M_0.3, 4 ± 4.7; M_0.6, 7.5 ± 5.5; M_0.8, 8 ± 5.5), subjective overall image quality and tumour delineation were significantly increased (all p < 0.001) with the non-linear blending technique compared to all investigated linear blending weighting factors. Overall interobserver agreement was substantial (ICC 0.70; 95% CI: 0.66-0.73). CONCLUSION: Post-processing of DECT using a non-linear blending technique provides improved objective and subjective image quality of head and neck SCC compared to linearly blended images series.

[Quantification of fluorescein angiography in patients with non-arteritic anterior ischemic optic neuropathy]. / Quantifizierung von Fluoreszenzangiographien bei Patienten mit nichtarteriitischer anteriorer ischämischer Optikusneuropathie.

PURPOSE: The aim of this study was to evaluate the retinal hemodynamics and optic disc leakage by fluorescein angiography in patients with non-arteritic anterior ischemic optic neuropathy (NAION) and to correlate fluorescein angiography findings with the extent and topography of visual field loss. METHODS: A total of 26 patients with acute NAION were included in the study. Fluorescein angiograms were performed by means of a scanning laser ophthalmoscope. The extent of early-phase optic disc leakage was assessed using a semiquantitative approach (focal versus diffuse type of leakage). Retinal arteriovenous passage (AVP) times were measured using dye dilution curves and digital image analysis for each hemisphere. The number of defective visual field points (StatPac: p<0.5%, uncorrected deviation plot) were evaluated (30/2 SITA, Humphrey-Zeiss) for the hemifields and different sectors. RESULTS: In this study of patients with NAION the mean AVP was 1.79 s±0.43 which was not significantly correlated to the number of defective points. Furthermore, AVP was not significantly different in focal versus diffuse optic disc leakage. The number of defective points were not significantly different in focal versus diffuse leakage of the optic disc (p=0.57). CONCLUSION: Retinal perfusion is not linked to the type and topography of disc leakage or the extent and topography of visual field damage in NAION. A global circulatory disorder e.g. due to a compartment syndrome of the optic nerve might account for these results.

[Sensitivity of imaging the peripheral nerve fibre layer using a confocal scanning laser ophthalmoscope to detect glaucoma]. / Sensitivität der Nervenfaserdarstellung mittels Scanning Laser Ophthalmoskop bei Glaukom.

PURPOSE: The aim of this study was to evaluate the sensitivity to detect glaucoma by observer-dependent nerve fibre layer imaging and evaluation using a scanning laser ophthalmoscope. PATIENTS AND METHODS: Fifty-four patients with primary open angle glaucoma (POAG), 41 patients with normal tension glaucoma (NTG) and 65 eyes of control subjects were included in a retrospective study. Nerve fibre layer imaging was performed using a confocal scanning laser ophthalmoscope (SLO, Rodenstock Instr., argon laser 488 nm). Digitised images of the nerve fibre layer were graded off-line by two masked experienced observers. The nerve fibre layer was graded for every single degree (defect or no defect) at 1.7 and 3.4 mm distance to the optic nerve head omitting the nasal 110 degrees. Sensitivity and specificity levels were calculated using ROC analysis. RESULTS: Patients with POAG exhibited nerve fibre layer defects of 100 degrees +/- 94 degrees (1.7 mm and 3.4 mm distance) and patients with NTG of 94 degrees +/- 94 degrees (1.7 mm distance) and 103 degrees +/- 92 degrees (3.4 mm distance), significantly larger compared to controls (1 degrees +/- 3 degrees [1.7 mm, p < 0.0001] and 1 degrees +/- 4 degrees [3.4 mm, p < 0.0001]). Sensitivity at > 90 % specificity was 80 % (1.7 mm) and 82 % (3.4 mm) for POAG. In NTG, sensitivity at > 90 % specifity was 81 % (1.7 mm) and 85 % (3.4 mm). In early glaucoma (MD < -6 dB, n = 39) sensitivity decreased to 75 % (1.7 mm) and 81 % (3.4 mm). CONCLUSION: Observer-dependent evaluation and grading of the nerve fibre layer using a scanning laser ophthalmoscope reaches considerably high sensitivity levels to detect glaucoma with negligible differences between the central and peripheral regions.

Skin response using NIH consensus criteria vs Hopkins scale in a phase II study for steroid-refractory chronic GVHD.

One of the obstacles to chronic GVHD research is the lack of standardized response criteria. The National Institute of Health (NIH) has recommended response criteria at a Consensus Conference. These need to be validated. We recently completed and reported a trial of pentostatin in treating steroid-refractory chronic GVHD. During the trial, we prospectively collected percent body-surface-area (BSA) involvement of rash, superficial sclerosis and deep sclerosis. Here, we compare cutaneous responses using the NIH scale and the Hopkins scale. The two scales produced similar overall response rates but different domain response rates. There was 80% agreement in overall response at the final treatment evaluation, but only a 64% agreement for fasciitis/non-moveable sclerosis. There was more disparity in the measurement of sclerosis than in that of erythema, which highlights the difficulty of quantifying sclerosis. For sclerosis, the Hopkins scale, which used skin softening, was more predictive of early response as compared with the NIH scale, which focused on percent BSA. Early assessment of skin softening may be important if trying to detect the activity of a particular agent in chronic GVHD. Further validation of the NIH scale is ongoing, which should produce a clinically useful and predictive scale.

Performance of colour Doppler imaging discriminating normal tension glaucoma from healthy eyes.

PURPOSE: Previous studies have shown decreased retrobulbar blood flow in normal tension glaucoma (NTG) compared to healthy controls. This study evaluates the ability of colour Doppler imaging (CDI) to identify patients with NTG. METHODS: Sixty-two patients with untreated NTG (mean age 57+/-14 years) and 40 age-matched controls (mean age 58+/-9 years) were included in a prospective cross-sectional institutional study. Peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive indices (RI=(PSV-EDV)/PSV) of the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (PCAs) were measured by means of CDI. Using receiver operating characteristic (ROC) curves, sensitivity was determined at 90% specificity. RESULTS: Patients with NTG showed significantly decreased PSV (P<0.0001) and EDV (P<0.0001) of the CRA, significantly decreased EDV of the nasal (P=0.004) and temporal (P=0.002) PCA, and significantly increased RI of the temporal (P=0.003) PCAs compared to healthy controls. Sensitivity values at 90% specificity were calculated: PSV of the CRA, 30.6%; EDV of the CRA, 48.4%; EDV of the nasal PCA, 43.9%; EDV of the temporal PCA, 45.9%; and RI of the temporal PCA, 39.3%. CONCLUSIONS: The power to identify NTG using CDI reaches 48% sensitivity at 90% specificity. Further longitudinal studies are needed to determine the prognostic value of CDI in glaucoma.

Amniotic membrane transplantation in severe ocular surface disorders.

PURPOSE: Amniotic membrane transplantation is currently being used as an alternative approach to treat severe corneal surface disorders refractory to medical therapy. The authors report complications of corneal surface disorders after successful amniotic membrane transplantation. METHODS: Case series. RESULTS: Twenty-eight patients with corneal surface disorders due to severe chemical burns, corneal ulceration, or persistent epithelium defects were treated with amniotic membrane transplantation. Four of these patients showed a spontaneous perforation and three patients developed a descemetocele within 6 weeks after the amniotic membrane transplantation. CONCLUSIONS: In this case series, descemetocele and corneal perforation occurred in 25% of the patients after amniotic membrane transplantation. This might be due to the severity of the underlying disease or to the impact of amniotic membrane on corneal fibroblasts and collagenases. The risk of corneal thinning and perforation should be considered in the decision of treatment with amnion and follow-up regimen.

Retrobulbar haemodynamics and morphometric optic disc analysis in primary open-angle glaucoma.

BACKGROUND: Previous studies confirmed reduced retrobulbar haemodynamics in primary open-angle glaucoma (POAG). AIM: To investigate a correlation between retrobulbar haemodynamics and morphometric neuroretinal rim analysis in patients with POAG. METHODS: 51 patients with POAG (mean (standard deviation (SD)) age 65 (11) years) were included in this clinical study. Blood flow velocities (peak systolic velocity (PSV) and end-diastolic velocity (EDV)) of the ophthalmic artery, central retinal artery (CRA), posterior ciliary arteries (PCA) and central retinal vein were measured using colour Doppler imaging (Siemens Sonoline Sienna, Erlangen, Germany). Optic disc morphometry was carried out using scanning laser tomography (Heidelberg Retinal Tomograph II Heidelberg Egineering Heidelberg, Germany). The stereometric parameters of the neuroretinal rim (rim area, rim volume, cup shape measure and retinal nerve fibre layer (RNFL) cross-sectional area) were used for analysis. RESULTS: The PSV of the CRA was significantly (p<0.001) correlated with rim area (r = 0.50) and rim volume (r = 0.51). The minimum velocities of the central retinal vein were significantly (p<0.001) correlated with rim volume (r = 0.56) and RNFL cross-sectional area (r = 0.49). No correlations were found for the flow velocities of the ophthalmic artery and PCAs. CONCLUSION: Retrobulbar haemodynamics of the central retinal artery and vein are correlated with the neuroretinal rim damage in POAG.

Retrobulbar haemodynamics in non-arteritic anterior ischaemic optic neuropathy.

AIM: To compare retrobulbar haemodynamics in patients with acute non-arteritic anterior ischaemic optic neuropathy (NAION) and age-matched controls by colour Doppler imaging (CDI). METHODS: 25 patients with acute NAION and 35 age-matched controls participated in this study. By means of CDI, the blood flow velocities of the ophthalmic artery, central retinal artery (CRA), and nasal and temporal short posterior ciliary arteries (PCAs) were measured. Peak-systolic velocity (PSV) and end-diastolic velocity (EDV) and Pourcelot's resistive index were determined. RESULTS: In the ophthalmic artery, no marked differences between patients with NAION and controls were detected. PSV and EDV of the CRA (p<0.001, p = 0.002) and PSV of the nasal PCA (p<0.05) were significantly decreased in patients with NAION compared with healthy controls. No marked differences between patients and controls were detectable for temporal PCAs. CONCLUSION: Blood flow velocities of the nasal PCA and the CRA are considerably reduced in patients with acute NAION compared with controls. Patients with NAION in part showed markedly different retrobulbar haemodynamics.

24-h blood pressure monitoring in normal tension glaucoma: night-time blood pressure variability.

Systemic arterial hypotension, hypertension and altered ocular blood flow are known risk factors in glaucoma. In this study, 24-h ambulatory blood pressure monitoring was performed in patients with normal tension glaucoma (NTG) and controls to evaluate blood pressure variability. In all, 51 patients with NTG and 28 age-matched controls were included in this prospective study. A 24-h ambulatory blood pressure monitoring (SpaceLabs Medical Inc., Redmond, USA) was performed and systolic, diastolic and mean arterial blood pressures were measured every 30 min during daytime (0800-2000) and night time (0000-0600). To evaluate blood pressure variability a variability index was defined as the s.d. of blood pressure measurements. Night-time blood pressure depression ('dip') was calculated (in percent of the daytime blood pressures). Patients with NTG exhibited higher night-time diastolic (P = 0.01) and mean arterial blood pressure values (P = 0.02) compared to controls, whereas systolic blood pressure data were not significantly different. The variability indices of night-time systolic, diastolic and mean arterial blood pressure measurements were significantly increased in patients with NTG compared to controls (P < 0.05). The night-time blood pressure depression of systolic (P = 0.47), diastolic (P = 0.11) and mean arterial blood pressures (P = 0.28) was not significantly different between patients with NTG and controls. In conclusion, patients with NTG showed increased variability of night-time blood pressure measurements compared to controls. Increased fluctuation of blood pressure may lead to ocular perfusion pressure fluctuation and may cause ischaemic episodes at the optic nerve head.

Effects of brinzolamide on ocular haemodynamics in healthy volunteers.

AIM: A prospective, randomised study to evaluate effects of brinzolamide on ocular haemodynamics in healthy volunteers. METHODS: 30 volunteers (12 men, 18 women; 28.3 (SD 7.8) years) were prospectively randomised to either brinzolamide or placebo during a 2 week double masked treatment trial. Examinations were performed at baseline and after 2 weeks of treatment. Intraocular pressure was measured and automatic static perimetry (Humphrey field analyser, 24-2) and contrast sensitivity (CSV 1000, Vector Vision) were performed. Retrobulbar blood flow velocities (peak systolic and end diastolic velocity) and resistive indices (RI) of ophthalmic artery, central retinal artery and of temporal and nasal short posterior ciliary arteries were measured by colour Doppler imaging (Sonoline Sienna Siemens). In video fluorescein angiograms (scanning laser ophthalmoscope, Rodenstock) arteriovenous passage time (AVP, dilution curves) and peripapillary diameters of retinal arterioles and venules were measured by means of digital image analysis. RESULTS: Intraocular pressure was significantly decreased by brinzolamide (p<0.0001). Neither brinzolamide nor placebo changed visual field global indices after treatment. Contrast sensitivity at 3 cycles per degree was significantly higher in the placebo group (p<0.05). Apart from an increase of RI in ophthalmic artery under placebo treatment (p<0.05) there was no effect in retrobulbar haemodynamics in both groups. Brinzolamide therapy alone resulted in a significant reduction of AVP compared to baseline (p<0.05), while peripapillary retinal vessels diameters remained unaffected. CONCLUSIONS: Apart from the expected decrease of intraocular pressure brinzolamide showed no significant change in retrobulbar haemodynamics, but a significant shortening of AVP. Since in glaucoma AVP is prolonged indicating vascular dysfunction this effect might be beneficial in glaucoma therapy.

Histocytological evaluation of the reaction of rat pulp tissue to Carisolv.

OBJECTIVES: Carisolv is a viscous substance for the chemo-mechanical removal of caries. The aim of this study was to examine the tissue reactions of pulp and dentin tissue to Carisolv in vivo. METHODS: In 48 caries-free molars (24 Wistar rats, age: 3 months) an occlusal cavity was prepared. The roofs of the pulp chambers were perforated with a sharp probe and Carisolv solution was placed onto the exposed pulp of 24 molars for 1, 10 and 20 min. Twenty-four contralateral molars served as controls and were coated with an inert liquid containing isotonic saline solution, carmellose and erythrosin. RESULTS: After a contact period of 10 and 20 min in the experimental group, pulpal destruction of intercellular substance and cells including odontoblasts was observed up to a depth of 150 microm, in addition to the mechanical damage by perforation (e.g. dentin particles). The pulpal and predentin fibrils as well as the dentin fibrils appeared to be intact and did not differ from the controls. After a contact time of 1 min a weaker damage of pulp cells and odontoblasts, as well as intact fibrils in pulp, predentin and dentin could be observed. CONCLUSIONS: Radicals of Carisolv (OH- and OCI-) cause alkaline hydrolysis of cellular components but do not decompose collagenous tissue components.

High concentrations of fluoride and boron in drinking water wells in the Muenster region--results of a preliminary investigation.

In 1998, two cases of severe dental fluorosis in schoolchildren occurred in the Muenster region. These cases took place in one household, where fluoridated toothpaste, fluoridated salt, and fluoride tablets were consumed. Furthermore, the family used drinking water from its private well only. Analyses of the well water ordered by local health officials revealed very high amounts of fluoride, boron, and other electrolytes. This unusual combination of high amounts of fluoride and boron could also be found in the water of a great number of other private wells that are the only source for drinking water in this rural region of the Muensterland. Anthropogenic sources could be excluded. Because of this, the results of the water samples were collated to the specific geological situation in this area. In the Muenster region there are marl layers of the chalk era covered with quarternary sediments. The quarternary sediments are up to 10 to 20 metres thick and they usually conduct the groundwater. The marl contains high concentrations of fluoride and boron. In some places the groundwater has contact with these layers. To check the amount of fluoride and boron in the groundwater, indicator values were sought, which can give a hint of high contents of these trace elements. In this study the conductivity and acidity were identified as possible indicators of a high amount of fluoride and boron in the drinking water in this specific region. To work economically and efficiently, the drinking water should be checked for fluoride and boron on a regular basis only when these values are extraordinarily high. In the case of high concentrations, especially of fluoride, in the drinking water the persons concerned should be informed about their potential health risk, giving them the opportunity to optimise the total daily intake of fluoride.

Effect of transcutaneous electrical nerve stimulation on pain perception threshold of human teeth: a double-blind, placebo-controlled study.

In this double-blind, placebo-controlled study, we studied the effect of three different transcutaneous electrical nerve stimulation (TENS) devices with extra- and intraoral electrodes on the pain perception thresholds of 234 unrestored, caries-free human teeth of 66 healthy individuals subjected to stimulation with an electric pulp tester. A placebo control collective of 64 healthy subjects received no electrical stimulation, since an inactive TENS device was used. In all tooth types tested (maxillary and mandibular incisors and premolars), the use of the active TENS devices resulted in an increase of 16.3-32.5% versus baseline in the pain perception threshold. The differences between active TENS and baseline were statistically significant for both TENS devices using extraoral electrodes (P < 0.05). No statistically significant differences were found between the different devices tested (P > 0.05). In the placebo collective, the increase in the pain perception threshold ranged between 6.4% and 10.3% versus baseline. There were no significant differences between placebo TENS and baseline on the one hand and between placebo TENS and the active TENS devices on the other hand (P > 0.05). The findings suggest that, as an alternative to local anesthetics, TENS seems not to be useful in the case of painful dental interventions, since it offered only minor advantages over a placebo.