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Tobacco industry consumer research on socially acceptable cigarettes.

OBJECTIVE: To describe tobacco industry consumer research to inform the development of more "socially acceptable" cigarette products since the 1970s. METHODS: Analysis of previously secret tobacco industry documents. RESULTS: 28 projects to develop more socially acceptable cigarettes were identified from Philip Morris, RJ Reynolds, British American Tobacco, and Lorillard tobacco companies. Consumer research and concept testing consistently demonstrated that many smokers feel strong social pressure not to smoke, and this pressure increased with exposure to smoking restrictions. Tobacco companies attempted to develop more socially acceptable cigarettes with less visible sidestream smoke or less odour. When presented in theory, these product concepts were very attractive to important segments of the smoking population. However, almost every product developed was unacceptable in actual product tests or test markets. Smokers reported the complete elimination of secondhand smoke was necessary to satisfy non-smokers. Smokers have also been generally unwilling to sacrifice their own smoking satisfaction for the benefit of others. Many smokers prefer smoke-free environments to cigarettes that produce less secondhand smoke. CONCLUSIONS: Concerns about secondhand smoke and clean indoor air policies have a powerful effect on the social acceptability of smoking. Historically, the tobacco industry has been unable to counter these effects by developing more socially acceptable cigarettes. These data suggest that educating smokers about the health dangers of secondhand smoke and promoting clean indoor air policies has been difficult for the tobacco industry to counter with new products, and that every effort should be made to pursue these strategies.

Adolescent↗

Contrast-enhanced, high-resolution, susceptibility-weighted magnetic resonance imaging of the brain: dose-dependent optimization at 3 tesla and 1.5 tesla in healthy volunteers.

OBJECTIVES: We sought to determine the optimal dose of a contrast agent with known high relaxivity on 1.5 and 3 Tesla scanners that would achieve the best compromise between image quality and scan time for the clinical application of contrast-enhanced susceptibility-weighted imaging (CE-SWI). METHODS: Pre- and postcontrast SWI was performed with different contrast agent doses (0.05, 0.1, and 0.2 mmol/kg gadobenate dimeglumine) at both 1.5 and 3 T in 6 healthy volunteers, resulting in 72 examinations. Venograms were created from minimum intensity projection reconstructions over specified deep white matter volumes to enhance the visual appearance of connected venous structures. Three independent radiologists blindly rated the visibility of the veins on a continuous scale of 1 to 10. A general linear model was used for statistical evaluation, with fixed effects of the contrast agent dose, the field strength, the rater and the patients as a random effect. RESULTS: With CE-SWI, we found significant differences in the visibility of the deep veins dependent on the contrast media dose (P=0.02). At 3 T, the visibility of deep venous vessels, with regard to susceptibility effect, image quality, and scan time reduction after a standard contrast agent dose 0.1 mmol/kg was significantly better than that achieved with 0.05 mmol/kg. The visibility was considered equal with 0.1 mmol/kg of the contrast agent to the precontrast images and a dose of 0.2 mmol/kg. At 1.5 T, no significant difference was found between the 4 contrast agent doses. We found no difference in the visibility of the veins with the shorter sequences at 3 T compared with the sequences at 1.5 T. CONCLUSIONS: Only a standard dose (0.1 mmol/kg) of gadobenate dimeglumine is required to achieve the optimum susceptibility effect and image quality at 3 T, together with a reduced scan time. This result can be attributed to the higher relaxivity of gadobenate dimeglumine, compared with conventional gadolinium chelates.

Adult↗

Patient safety in the clinical laboratory: a longitudinal analysis of specimen identification errors.

CONTEXT: Patient safety is an increasingly visible and important mission for clinical laboratories. Attention to improving processes related to patient identification and specimen labeling is being paid by accreditation and regulatory organizations because errors in these areas that jeopardize patient safety are common and avoidable through improvement in the total testing process. OBJECTIVE: To assess patient identification and specimen labeling improvement after multiple implementation projects using longitudinal statistical tools. DESIGN: Specimen errors were categorized by a multidisciplinary health care team. Patient identification errors were grouped into 3 categories: (1) specimen/requisition mismatch, (2) unlabeled specimens, and (3) mislabeled specimens. Specimens with these types of identification errors were compared preimplementation and postimplementation for 3 patient safety projects: (1) reorganization of phlebotomy (4 months); (2) introduction of an electronic event reporting system (10 months); and (3) activation of an automated processing system (14 months) for a 24-month period, using trend analysis and Student t test statistics. RESULTS: Of 16,632 total specimen errors, mislabeled specimens, requisition mismatches, and unlabeled specimens represented 1.0%, 6.3%, and 4.6% of errors, respectively. Student t test showed a significant decrease in the most serious error, mislabeled specimens (P < .001) when compared to before implementation of the 3 patient safety projects. Trend analysis demonstrated decreases in all 3 error types for 26 months. CONCLUSIONS: Applying performance-improvement strategies that focus longitudinally on specimen labeling errors can significantly reduce errors, therefore improving patient safety. This is an important area in which laboratory professionals, working in interdisciplinary teams, can improve safety and outcomes of care.

Clinical Laboratory Techniques↗

Is the entire fundus of the internal auditory canal visible during the middle fossa approach for acoustic neuroma?

HYPOTHESIS: To determine the degree to which the fundus of the internal auditory canal (IAC) can be visualized during the middle fossa approach (MFA). BACKGROUND: Conventional wisdom states that the MFA provides excellent access to the IAC from the porus acusticus to the fundus. On the basis of observations derived from a substantial surgical experience, it became obvious that a variable fraction of the fundus lies obscure from the surgeon's line of sight during the MFA because of (1) the overhand of the transverse crest and/or (2) the immobility of the facial nerve at its entry into the fallopian canal. METHODS: Intraoperative measurements were performed in ten cases to determine the typical angle of view to the fundus of the IAC in the MFA. This angle of view was projected onto coronal computed tomography scans of 40 temporal bones. Measurements of the IAC were made to determine the amount of fundus that could not be directly visualized during a MF exposure. RESULTS: On the basis of a surgical line of sight, the fraction of the inferior compartment of the canal that could not be directly visualized because of overhand of the transverse crest ranged from 14% to 34% (median 25%). CONCLUSIONS: Complete resection of IAC tumors involving the fundus via the MFA requires some degree of blind dissection. Specialized tools and techniques are required to minimize the risk of neural injury during this indirect dissection. Inspection of the fundus with either mirror or endoscope is often necessary to exclude the possibility of retained tumor fragments.

Ear, Inner↗

How well does the Oxfordshire community stroke project classification predict the site and size of the infarct on brain imaging?

OBJECTIVES: The Oxfordshire Community Stroke Project (OCSP) classification is a simple clinical scheme for subdividing first ever acute stroke. Several small studies have shown that when an infarct is visible on CT or MRI, the classification predicts its site in about three quarters of patients. The aim was to further investigate this relation in a much larger cohort of patients in hospital with ischaemic stroke. METHODS: Between 1994 and 1997, inpatients and outpatients with ischaemic stroke were assessed by one of several stroke physicians who noted the OCSP classification. A neuroradiologist classified the site and extent of recent infarction on CT or MRI. RESULTS: Of 1012 patients with ischaemic stroke, 655 (65%) had recent visible infarcts. These radiological lesions were appropriate to the clinical classification in 69/87 (79%) patients with a total anterior circulation syndrome, 213/298 (71%) with a partial anterior circulation syndrome, 105/144 (73%) with a lacunar syndrome, and 105/126 (83%) with a posterior circulation syndrome. Overall, 75% of patients with visible infarcts were correctly classified clinically. If patients without a visible infarct did have an appropriate lesion in the brain (best case), the classification would have correctly predicted its site and size in 849/1012 (84%) patients, compared with only 492/1012 (49%) in the worst case scenario. CONCLUSION: The OCSP classification predicted the site of infarct in three quarters of patients. When an infarct is visible on brain imaging, the site of the infarct should guide the use of further investigations, but if an infarct is not seen, the OCSP classification could be used to predict its likely size and site.

Aged↗

Project examining effectiveness in clinical ethics (PEECE): phase 1-- descriptive analysis of nine clinical ethics services.

OBJECTIVE: The field of clinical ethics is relatively new and expanding. Best practices in clinical ethics against which one can benchmark performance have not been clearly articulated. The first step in developing benchmarks of clinical ethics services is to identify and understand current practices. DESIGN AND SETTING: Using a retrospective case study approach, the structure, activities, and resources of nine clinical ethics services in a large metropolitan centre are described, compared, and contrasted. RESULTS: The data yielded a unique and detailed account of the nature and scope of clinical ethics services across a spectrum of facilities. General themes emerged in four areas-variability, visibility, accountability, and complexity. There was a high degree of variability in the structures, activities, and resources across the clinical ethics services. Increasing visibility was identified as a significant challenge within organisations and externally. Although each service had a formal system for maintaining accountability and measuring performance, differences in the type, frequency, and content of reporting impacted service delivery. One of the most salient findings was the complexity inherent in the provision of clinical ethics services, which requires of clinical ethicists a broad and varied skill set and knowledge base. Benchmarks including the average number of consults/ethicist per year and the hospital beds/ethicist ratio are presented. CONCLUSION: The findings will be of interest to clinical ethicists locally, nationally, and internationally as they provide a preliminary framework from which further benchmarking measures and best practices in clinical ethics can be identified, developed, and evaluated.

Benchmarking↗

Long-term outcome of autogenous rib graft nasal reconstruction.

Whereas reconstruction of the hypoplastic nose with rib grafting is common, the long-term outcomes of nasal growth and aesthetics are unknown. This study assessed nasal morphometrics, patient satisfaction, and the perception of nasal appearance by others up to 15 years after nasal reconstruction using cantilevered autogenous chondro-osseous rib grafting with rigid internal fixation in children. Records of all patients who received nasal rib grafts between 1983 and 1998 by one senior surgeon were reviewed. Patients in this study were operated on before their late teens and had greater than 1-year follow-up including serial photographic documentation. Nasal growth was determined by comparing anthropometric measurements preoperatively, perioperatively, and postoperatively. Patient satisfaction was determined through a questionnaire that addressed memory, donor-site morbidity, and nasal perception. Independent, blinded skilled observers who reviewed frontal and lateral photographs of the preoperative, perioperative, and postoperative intervals assessed nasal aesthetics. Thirty-two patients who underwent 38 rib graft reconstructions of the nasal dorsum and tip at an average age of 8.8 years constitute the study population. Six patients underwent secondary augmentation. The average interval between initial nasal reconstruction and evaluation for this study was 7.9 years. Comparative anthropometric measurements before and after surgery documented increases in both tip projection (2.3 percent) and nasal length (3.0 percent) and a decrease in nasolabial angle (1.9 percent). Patient satisfaction interview response rate was 100 percent of those whom we were able to contact (28 of 32). The average age at interview was 17.2 years. Most patients recalled the operation and denied recollection of pain. Donor-site long-term morbidity was not an issue for 86 percent of patients. Sixty-four percent of patients remembered their preoperative nasal appearance and 89 percent of these preferred the postoperative change and were not concerned with nasal scars or texture. Almost two-thirds of the patients had fixation screws removed from the nasal dorsum because of skin erosion, easy palpability, or visibility. Although several patients expressed a desire to make minor additional changes to their nose, only one of these elected offered presurgical consultation and none have had such surgery. The postoperative nasal appearance compared with that preoperatively was rated as improved for 66.3 percent of responses, 26.5 percent as unchanged, and 7.2 percent as deteriorated. Cantilevered autogenous chondro-osseous rib graft reconstruction of the nasal dorsum is an effective means of reconstruction for the hypoplastic nose in childhood with respect to morphometric measurements, patient self-perception, and the assessment of nasal appearance by others.

Adolescent↗

[An analysis of the pharmaceuticals market in Vietnam].

This article sheds a light on the Vietnamese pharmaceutical market. The progress that has been made in the recent years following the opening of the Vietnamese regime to the western world, although not easy, brought a certain number of opportunities for domestic firms and foreign investors. The pharmaceutical Vietnamese industry started to emerge at the beginning of the 1990s. Although, the consumption of drugs is low, it does reach the sum of $ 5.5 per capita. As the majority of these products are imported, foreign companies tend to dominate the market both in volume and in diversity. The state has always played an important role with the implementation of a strict price control strategy and most national drug companies remain state-owned. The production and consumption of drugs were also largely influenced by state policies as the latter also control hospitals. In the second half of the eighties, the progressive liberalisation of the country allowed private drug pharmacies to appear and advertisement campaigns became legal. Because the lack of specific products like antibiotics was clear, the government increased the flow of imports, including private imports by citizens. Sources of imports have become more diverse, although France remains an important source of supply. Fournier, Lipha and Pierre Fabre are among the French drug manufacturers located in Vietnam. Other foreign companies include from India, South Korea, Thailand and Germany. Joint ventures were also created with French and Japanese companies. The import of medical materials is subjected to authorisations from the Ministry of Health and the Ministry of Foreign Trade as it is necessary to obtain a licence to do so. Licences are issued on the basis of the production of drugs that do not currently exist on the local market. But Vietnam also exports pharmaceutical products to Laos, Cambodia, and Cuba. Local resources constitute an important source of new products and have stirred a strong interest among pharmaceutical researchers. A strong decentralisation process characterises the pharmaceutical sector, with pharmacies in the provinces and districts while wholesalers remain located in Hanoi and Saigon. The presence of many middlemen has contributed to an increase in prices. Today, a concentration of pharmacies is still noted in inner cities while the suburbs and the villages still have difficulties supplying drugs for inhabitants. Solutions have been implemented such as the opening of new pharmacies and additional professional training for pharmacists. Prices were lowered while the quality of the supply chain was improved. Local production is encouraged as hospitals are prompted to prescribe Vietnamese products. The modernisation of the Vietnamese pharmaceutical industry is also visible through the importation of medical materials and an increase in the number of private hospitals financed with both the help of local and foreign investors, mainly through joint-ventures, most often in Saigon and Hanoi. The renovation of local hospitals was also possible with the help of France and Japan. Columbia Gia Dinh International, located in Saigon, is one of the very few US/Vietnamese medical institutions created with a local partner, the Gia Dinh hospital. The recovery of the economy will accelerate the creation of new projects designed to improve local medical infrastructures. Other private companies, some of which are based in Singapore, have been specifically designed to deliver care to expatriates working in Vietnam. Insurance coverage has been provided in Vietnam since in 1992. Other improvements concern the implementation of "Good Manufacturing Practices" (GMP) and "Good Laboratory Practices" and "Good Storage Practices". Most norms were implemented at the end of the 90s in joint companies linking foreign investors and local partners or in independent foreign drug manufacturers based in Vietnam. Special areas were created to receive high tech investments in the medical and pharmaceutical field. Prices should diminish as competition on the market increases and new products are placed on the market to achieve economies of scale. But investment in medical research is still strongly needed.

Advertising↗

Efficacy, cleaning ability and safety of different rotary NiTi instruments in root canal retreatment.

AIM: To evaluate the efficacy, cleaning ability and safety of three different rotary nickel-titanium instruments with and without a solvent (eucalyptol) versus hand files in the removal of gutta-percha root fillings. METHODOLOGY: Eighty extracted single-rooted anterior teeth were enlarged to size 35 and obturated with laterally condensed gutta-percha using AHPlus as the sealer. Removal of gutta-percha was performed with the following devices and techniques: FlexMaster, GT Rotary, ProTaper and Hedström files. All techniques were used with and without the solvent eucalyptol. The following data were recorded: time taken to reach the calculated working length and time required for the removal of gutta-percha. The teeth were split longitudinally and photographed. Cleanliness of the root canal walls was scored using the projected slides with a total magnification of approximately 70x. Statistical analysis was performed using the two-way anova (P < 0.001) for the analysis of working time. RESULTS: The technique that reached the working length most rapidly was that using ProTaper instruments and eucalyptol (+E), followed by FlexMaster + E, ProTaper, FlexMaster, Hedström files + E, GT Rotary + E, Hedström files, and GT Rotary. No significant differences were found for retreatment with or without a solvent in all groups. ProTaper and FlexMaster worked significantly more rapidly than Hedström files and GT Rotary (anova, P < 0.001). Time for complete removal of gutta-percha was again shortest with ProTaper + E, followed by FlexMaster + E, ProTaper, FlexMaster, GT Rotary + E, Hedström files + E, Hedström files, and GT Rotary. ProTaper and FlexMaster again worked significantly faster than the other techniques (anova, P < 0.001). There was no visible filling material extruded apically. Root canal cleanliness proved best following the use of FlexMaster + E, and Hedström files + E, followed by ProTaper + E, and GT Rotary + E. CONCLUSION: Under the experimental conditions, FlexMaster and ProTaper NiTi instruments proved to be efficient and time-saving devices for the removal of gutta-percha. The use of eucalyptol as a solvent shortened the time to reach the working length and to remove the gutta-percha, but this was not significant.

Cyclohexanols↗

Panoramic dental radiography as an aid in detecting patients at risk for stroke.

PURPOSE: Atherosclerotic lesions in the region of the bifurcation of the common carotid artery and in the internal carotid artery are the most common cause of stroke. On occasion these lesions are calcified and visible on a panoramic dental radiograph. METHODS: Six subjects receiving outpatient dental treatment and denying a history of previous transient ischemic attacks or stroke had bilateral calcified carotid arterial lesions noted on their routine panoramic dental radiograph. RESULTS: Electronic thermography (ET) demonstrated that these patients had significant temperature differences bilaterally between their medial supraorbital region and the ipsilateral remainder of their forehead when compared with control subjects. These findings are consistent with the presence of calcified stenotic intraluminal plaques altering blood flow, tissue perfusion, and skin temperature readings. The presence of stenotic plaques was verified by Doppler spectral analysis and imaging. CONCLUSION: ET of the face, currently considered an investigational procedure, demonstrates promise as an ancillary imaging system capable of confirming the diagnosis of patients at risk of stroke. Such individuals should be referred to an appropriate physician for consideration of medications and/or surgical removal of the plaque. In selected individuals, these are safe and relatively reliable methods of preventing stroke.

Aged↗

Protected renal stenting with the PercuSurge GuardWire device: a pilot study.

PURPOSE: To evaluate the feasibility and safety of renal artery angioplasty and stenting utilizing a distal protection device to reduce the risk of intraprocedural atheroembolism. METHODS: Twenty-eight hypertensive patients (18 men; mean age 71.3 +/- 8.6 years, range 49-87) with atherosclerotic renal artery stenosis (4 bilateral) underwent angioplasty and stenting with distal protection in 32 renal arteries (29 ostial lesions). The lesion was crossed with a GuardWire temporary occlusion balloon, which was inflated to provide parenchymal protection. Generated debris was aspirated and analyzed. Blood pressure and serum creatinine levels were followed. RESULTS: Immediate technical success was 100%. All lesions were stented, either directly (14 ostial lesions), after predilation (15 ostial lesions), or owing to suboptimal angioplasty (3 nonostial lesions). Visible debris was aspirated from all patients. Mean particle number and diameter were 98.1 +/- 60.0 per procedure (range 13-208) and 201.2 +/- 76.0 microm (range 38-6206), respectively. Mean renal artery occlusion time was 6.55 +/- 2.46 min (range 2.29-13.21). Mean follow-up was 6.7 +/- 2.9 months (range 2-17). Systolic and diastolic blood pressure declined from 167.0 +/- 15.2 and 103.0 +/- 12.0 mm Hg, respectively, to 154.7 +/- 12.3 and 93.2 +/- 6.8 mm Hg after the procedure. The mean creatinine level dropped from 1.34 +/- 0.35 mg/dL preprocedurally to 1.22 +/- 0.36 mg/dL at 24 hours and remained constant. At 6-month follow-up, renal function did not deteriorate in any patient, whereas 5 patients with baseline renal insufficiency improved after the procedure. CONCLUSIONS: These preliminary results suggest the feasibility and safety of distal balloon occlusion during renal interventions to protect against atheroembolism. This technique's beneficial effects should be evaluated by randomized studies.

Aged↗

Acetabular anatomy and the relationship with pelvic vascular structures. Implications in hip surgery.

Most direct vascular trauma occurring during hip surgery results from injury to pelvic vascular structures which are not visible during the procedures of reaming, drilling holes or the fixation of screws. In this study, 5 pelves of fresh cadavers were injected with a radiopaque mixture and were visualised with a scanner according to 5 predetermined sections. Bone depth of the acetabulum was measured in each section. A calculation was made describing the minimal distance separating the inner cortex from the principal pelvic vessels. After an anatomic dissection of each pelvis, the relationship between the vessels and screws of the fixation cup, implanted identically on the quadranted acetabulum, was observed. The screws placed in the anterior and inferior quadrants and the center of the acetabulum endangered the external iliac v. and a. and the obturator pedicle. The depth of the periacetabular bone was greater in the superior and posterior quadrants. The inferior gluteal, pudendal and superior gluteal aa. were more than ten mm from the posterior wall. Conversely, the external iliac and obturator pedicles came in contact with the osseous surface on which they lay. A projection of the vessels on the acetabulum was made, and the reproducible character of the acetabular-quadrant system was verified. The superior quadrant offers all the characteristics of a vascular safe zone. A knowledge of these anatomic relationships explain vascular trauma in pelvic fractures and helps to prevent vascular injury in hip surgery.

Acetabulum↗

Assessment of regional lung functional impairment with co-registered respiratory-gated ventilation/perfusion SPET-CT images: initial experiences.

In this study, respiratory-gated ventilation and perfusion single-photon emission tomography (SPET) were used to define regional functional impairment and to obtain reliable co-registration with computed tomography (CT) images in various lung diseases. Using a triple-headed SPET unit and a physiological synchroniser, gated perfusion SPET was performed in a total of 78 patients with different pulmonary diseases, including metastatic nodules (n = 15); in 34 of these patients, it was performed in combination with gated technetium-99m Technegas SPET. Projection data were acquired using 60 stops over 120 degrees for each detector. Gated end-inspiration and ungated images were reconstructed from 1/8 data centered at peak inspiration for each regular respiratory cycle and full respiratory cycle data, respectively. Gated images were registered with tidal inspiration CT images using automated three-dimensional (3D) registration software. Registration mismatch was assessed by measuring 3D distance of the centroid of the nine selected round perfusion-defective nodules. Gated SPET images were completed within 29 min, and increased the number of visible ventilation and perfusion defects by 9.7% and 17.2%, respectively, as compared with ungated images; furthermore, lesion-to-normal lung contrast was significantly higher on gated SPET images. In the nine round perfusion-defective nodules, gated images yielded a significantly better SPET-CT match compared with ungated images (4.9 +/- 3.1 mm vs 19.0 +/- 9.1 mm, P<0.001). The co-registered SPET-CT images allowed accurate perception of the location and extent of each ventilation/perfusion defect on the underlying CT anatomy, and characterised the pathophysiology of the various diseases. By reducing respiratory motion effects and enhancing perfusion/ventilation defect clarity, gated SPET can provide reliable co-registered images with CT images to accurately characterise regional functional impairment in various lung diseases.

Adult↗

In vivo real-time confocal reflectance microscopy: a noninvasive guide for Mohs micrographic surgery facilitated by aluminum chloride, an excellent contrast enhancer.

BACKGROUND: Mohs micrographic surgery (MMS) is based on microscopically controlled excision of cutaneous neoplasms and offers the highest cure rates with maximum tissue preservation. In vivo confocal microscopy (CM) allows noninvasive optical imaging of thin sections of living skin, in its native state, in real time, with high resolution and contrast. OBJECTIVE: To evaluate the feasibility of the use of in vivo CM as a surgical guide in MMS. METHODS: Five patients with a biopsy-proven basal cell carcinoma (BCC) were imaged by in vivo CM on one or two sites from the clinically visible skin cancer. The first Mohs layer was then excised, and the fresh-frozen sections were correlated with the CM findings. Aluminum chloride (AlCl) 20% was applied on the Mohs defect followed by in vivo CM on one site from each lesion. A second Mohs layer was subsequently excised, and fresh-frozen sections were correlated with CM findings. RESULTS: The findings of in vivo CM were confirmed by hematoxylin and eosin-stained frozen sections after excisions of the first and second Mohs layers. AlCl was found to provide an excellent contrast between BCC cells and the surrounding tissue, detected readily with both in vivo and ex vivo CM. The tumor cells with AlCl exhibited intensely bright nuclei with an excellent contrast as compared with the low-contrast dark nuclei without AlCl application. CONCLUSION: In vivo CM is a potential surgical guide for MMS, and AlCl provides an excellent exogenous agent to enhance tumor contrast for CM.

Aged↗

Three-dimensional, non-destructive visualization of vertical root fractures using flat panel volume detector computer tomography: an ex vivo in vitro case report.

AIM: To detect and to visualize radiographically vertical root fractures in extracted teeth with a prototype of a novel, high resolution, three-dimensional flat panel volume detector computer tomograph (FD-VCT) system. SUMMARY: Five teeth with root fillings and clinical symptoms such as fistulas and isolated periodontal pockets of 8 mm or more were extracted after dental radiography indicating lateral or periapical lesions. Vertical root fractures or cracks were suspected because of the symptoms and clinical findings were evident after extraction in all cases but fracture lines were not visible on routine dental radiographs acquired before extraction. The extracted teeth were explored with a prototype of a FD-VCT. Using the FD-VCT, in all cases vertical root fractures or crack lines could be detected clearly in different views, depiction-modes and cross-sections at a spatial resolution of 140 microm. The evaluation of the fracture lines and teeth could be performed in three-dimensional views. The FD-VCT findings were confirmed by detailed inspection of the extracted teeth. KEY LEARNING POINTS: The FD-VCT is an innovative diagnostic tool for non-destructive, three-dimensional evaluation of extracted teeth in pre-clinical and experimental studies. The FD-VCT allows precise visualization and evaluation of vertical root fractures or cracks in extracted teeth. Clinical application of the system may be possible if technical modifications reduce the exposure dose: the high resolution detector systems of the FD-VCT should be combined with radiation systems that focus the radiation to the area of interest.

Humans↗

Evaluation of cancer prevention strategies by computerized simulation model: methodological issues.

A computerized simulation model developed to evaluate the potential impact of primary and secondary prevention is discussed from methodologic perspectives. In the simulation model, named CANSAVE (Cancer Strategy Analysis and Validation of Effect), the natural history of cancer was modeled as a Markovian stochastic process from cancer-free state to death. The lung cancer death rate among Japanese males was projected for 50 years to the year 2041. The simulation showed that the age-adjusted death rate would increase and reach a peak of 166 per 100,000 in 1989 and then decrease to 148 in 2003. It then shows a tendency to increase again, up to 255 in 2028. This change may be attributed to a lower smoking initiation rate among those born in the 1930s. Promotion of mass screening programs exhibits a more prompt effect than antismoking efforts, but the reduction in annual deaths is expected to be only 11%, even if a 100% participation is realized by the year 2000. The reduction in smoking initiation rate, on the other hand, begins to show a visible effect very slowly. It was predicted that a 1% annual reduction in smoking initiation rate would result in a 20% decrease in the number of deaths in 2041. The smoking cessation program is in the middle with regard to promptness. The predicted reductions in lung cancer deaths in 2041 were 13, 47, and 66%, respectively, when the annual smoking cessation rate was increased from 0.46% (present status) to 1, 3, and 5%. The combined application of all three preventive measures seems essential to realize the most effective reduction in lung cancer deaths.

Adult↗

Characteristics of the Orthopantomograph OP 100.

OBJECTIVE: To investigate empirically the imaging characteristics of the Orthopantomograph OP 100 and compare them to the average form of the dental arch. METHODS: Repeatable radiographs were taken of a lead resolution grid positioned at 1 mm increments along known angular intervals of the projected X-ray beam. Focal trough thickness was determined by visibility of the 1.5 lp mm-1 resolution limits. The path of the effective rotation center was determined using a film positioned at right angles to the slit beam. The vertical magnification and horizontal magnification and distortion index, corrected for the position of the tomographic layer, were calculated using a reference object placed at various resolution limits of the focal trough. The beam projection angle was calculated with respect to the central plane of the focal trough and the average dental arch shape compared with the average proximal contact angle. RESULTS: The maximum resolution observed at the central plane of the focal trough was 5 lp mm-1. The width of the focal trough varied from 17 mm in the anterior region to 44 mm in the posterior region. The path of the effective rotation center was found to translate between three fixed centers of rotation, with the effective anterior projection radius of 24 mm. The vertical magnification factor within the focal trough showed a linear increase along the beam path from 1.24-1.37 and the horizontal magnification varied from 1.01-1.63. The distortion index varied from 0.84-1.24. The beam projection angle increased from 90 degrees anteriorly to 115 degrees in the premolar area with respect to the central plane of the focal trough and from 90 degrees anteriorly to 110 degrees in the premolar area compared with the average dental arch. CONCLUSIONS: The OP 100 provides a focal trough conforming well to the overall geometry of the dental arch and provides adequate spatial resolution.

Dental Arch↗

High frame-rate simultaneous bilateral breast DCE-MRI.

A simultaneous bilateral back-projection method for 3D dynamic contrast-enhanced (DCE)-MRI of the breasts was developed and evaluated. Using a double-side band modulation of the RF slab excitation pulse, discontinuous volumes that included both breasts were simultaneously selected. The number of slice phase-encoding steps was undersampled by a factor of 2, and the resulting signal aliasing from one volume to the other was removed using SENSE processing. In-plane encoding was performed with an interleaved radial acquisition reconstructed using dynamic k-space-weighted image contrast (KWIC) temporal filtering. Image resolution was 0.5 x 0.5 x 3.0 mm(3) with an effective temporal resolution of 15 s for both breast volumes. Combined with the 2x acceleration from SENSE encoding, this is a 16x acceleration factor over a conventional MR bilateral breast scan. An initial evaluation of these methods was performed on a cohort of women who presented with palpable or mammographically visible breast abnormalities. A total of 73 abnormalities were found in 45 of the 54 bilateral examinations that were performed. In 11 of these cases there was a significant finding in the contralateral breast. DCE images of both breasts can be acquired simultaneously, resulting in high-resolution images as well as rapid sampling of the contrast kinetics.

Breast↗