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To verify if assessment of the danger zone (DZ) in the mesial root of mandibular molars is affected by field of view (FOV) and voxel sizes in cone beam computed tomography (CBCT) scans. Forty mandibular molars were scanned by micro-computed tomography, creating the reference standard. The teeth were then submitted for CBCT scans with FOVs of 10 × 5.5 cm and 5 × 5.5 cm and voxel sizes of 0.4, 0.2, 0.15, and 0.075 mm3. The smallest dentin thickness in the DZ from the mesiobuccal and mesiolingual canals was measured at 2, 4, and 6 mm apical to the root furcation. Descriptive statistics, paired t-tests, and intraclass correlation coefficients were used for statistical analysis with significance established at P <.05. All CBCT measurements overestimated the DZ dentin thickness (P <.001) compared to the reference standard. The greatest overestimation occurred in the 5 × 5.5 cm FOV with 0.4 mm3 voxels (P =.007). Dentin thickness measured with the 5 × 5.5 cm FOV and 0.075 mm3 voxels was significantly smaller and produced the best ICC value with the reference standard (0.936). CBCT overestimates the dentin thickness of the DZ regardless of FOV and voxel sizes. The 5 × 5.5 cm FOV showed the best performance with the 0.075 mm3 voxel size, but it performed poorly with 0.4 mm3 voxels. [ABSTRACT FROM AUTHOR]

This study evaluated the performance of the metal artifact reduction (MAR) tool in cone-beam computed tomographic scans using different fields of view (FOVs) in the detection of a root isthmus in mandibular molars with intraradicular posts. Twenty-eight teeth were scanned by micro–computed tomographic imaging (gold standard images). Thereafter, specimens were allocated into the following groups: gutta-percha (teeth without posts, n = 10), a prefabricated metal post (n = 9), and a fiberglass post (n = 9). Cone-beam computed tomographic scans were taken using 8 acquisition protocols, varying the size of the FOV (10 × 5.5 cm and 5 × 5.5 cm) and the MAR tool (disabled, low, normal, and high modes). A root isthmus was evaluated considering a 5-point scale. Data were analyzed considering a 5% significance level. Intra- and interexaminer agreement varied from moderate to substantial. The frequency of correct diagnosis varied significantly in all groups regardless of the image acquisition protocol selected (P <.05). In the gutta-percha group, there was no difference in the accuracy, sensitivity, and specificity values between the tested protocols. In the metal and fiberglass post groups, the accuracy values were higher with the "disabled" and "low" modes of the MAR tool regardless of the FOV size. This was also observed for the sensitivity values in the metal post group (P <.05). The size of the FOV did not affect the performance of the MAR tool in the diagnosis of a root isthmus in molars with intraradicular posts. Our findings suggest that the use of the tool in the "normal" and "high" modes is contraindicated for this purpose. [ABSTRACT FROM AUTHOR]

Aim To investigate the role of 18F–NaF PET/CT and compare it with 99m Tc-MDP whole body bone scintigraphy and 18F-FDG PET/CT in detecting the extent of metastatic bone disease and to present our first experience with 18F–NaF PET/CT in our country. Materials and methods A total of 37 histopathologically proven cancer patients (22 male, 15 female) with bone metastasis detected on Tc-99m MDP whole body bone scan were prospectively enrolled Cebeci, following ethics committee approval. 18F–NaF PET/CT was performed to the participants in Ankara University Medical Faculty Nuclear Medicine Department for evaluation of symptomatic skeletal sites which were negative on Tc-99m MDP whole body bone scan. A lesion based comparison was made between 18F–NaF PET/CT and Tc-99m MDP whole body bone scan for each patient and between 18F–NaF PET/CT and 18F-FDG PET/CT in 12/37 patients. Results The number of lesions demonstrated by 99m Tc-MDP bone scan and 18F–NaF PET/CT was equal in 4/37 (%11) of the cases. 18F–NaF PET/CT showed a greater number of pathological foci in 89% of participants. 18F–NaF PET/CT was able to show both lytic and blastic lesions and small lesions were better visualized due to the advantage of sectional imaging with much better resolution and higher target/background ratio. 18F–NaF PET/CT demonstrated a greater number of metastases in 10/12 (83%) of the patients when compared to 18F-FDG PET/CT. In the other two patients, bone metastasis could be demonstrated only by 18F–NaF PET/CT. The uptake of 18F-FDG was variable in blastic lesions and cranial bone involvement was missed by 18F-FDG PET/CT in some cases due to physiological brain metabolism. Conclusion Although further prospective clinical studies in specific cancer populations are indicated to set the place of 18F–NaF PET/CT in diagnostic scheme, the results of this pilot study from our country support the superiority of 18F–NaF PET/CT in investigation of bone metastasis over 99mTc-MDP bone scan and 18F-FDG PET/CT in various malignancies. 18F–NaF PET/CT is coming forward as a single step bone seeking study, considering all the advantages, but especially potential of detecting occult metastases and reliably directing patient management. [ABSTRACT FROM AUTHOR]

Objective: It has been reported that both obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD) might be related to impairments in frontal-striatal brain circuits. Besides, these two disorders are frequently comorbid. However, there are no published studies directly comparing the neurobiological findings in these two disorders. The objective of the study was to investigate the differences in cortical blood flow between patients with OCD and ADHD. Method: Thirteen drug-naive OCD subjects (mean age ± SD: 10.4 ± 2.8), and 13 drug-naive ADHD subjects (mean age ± SD: 10.5 ± 2.2) were included in the study. Cerebral blood flow (CBF) was evaluated with Tc-99m-hexamethylpropyleneamine oxime (Tc99m HMPAO) brain single photon emission tomography (SPECT) during standard resting conditions in all cases. P value was set to <.006 after Bonferroni correction. Results: OCD cases had significantly higher right prefrontal (p=.003) CBF than ADHD cases. There were no significant CBF differences in other brain regions. OCD symptom severity was not related to CBF. Discussion: This is one of the very few studies which directly investigated brain imaging in pediatric OCD subjects. Results are consistent with previous studies reporting increased prefrontal CBF in OCD subjects. We also found that, consistent with the previous literature, ADHD subjects had lower prefrontal cortex CBF. Studies which compare subjects with comorbid ADHD and OCD with pure forms of these disorders are necessary to have a better understanding of similarities and differences of these two disorders. [ABSTRACT FROM AUTHOR]

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