Detection and Characterization of Parathyroid Adenoma/Hyperplasia for Preoperative Localization: Comparison Between 11C-Methionine PET/CT and 99mTc-Sestamibi Scintigraphy

Purpose

¹¹C-Methionine PET/CT (Met-PET/CT) is a useful imaging method for detection of parathyroid adenoma; however, the reported detection rate has been variable. The current study was intended to investigate detection sensitivity and preoperative localization of parathyroid adenoma (PA) or parathyroid hyperplasia (PH) on Met-PET/CT compared with ^99mTc-sestamibi (MIBI) scintigraphy in patients with primary hyperparathyroidism (HPT) or suspected PA.

Methods

Met-PET/CT and MIBI scintigraphy images were reviewed by two nuclear medicine physicians unaware of pathologic results. Detection sensitivities and preoperative localization of detected parathyroid tissues into five predefined segments were evaluated by visual assessment and semi-quantitative analysis with ratio of standardized uptake values (SUVR) between parathyroid tissue and normal lung as reference. Linear regression analysis with SUVR and serum parathyroid hormone (sPTH) was performed for characterization of PA or PH. Predicted PTH (pPTH) was calculated and compared with sPTH in PH and PA. Each pPTH was obtained for a calculated SUVR by using linear regression model from the result of previous linear regression analysis between SUVR and sPTH.

Results

In 16 patients, detection sensitivities of Met-PET/CT and MIBI scintigraphy were 91.7 % (11/12) and 41.7 % (5/12) for PA and PH including both biopsy-confirmed and clinically-suspected cases, and 100 % (8/8) and 50 % (4/8) for pathologically confirmed PA and PH cases only, respectively. Met-PET/CT showed higher performance than MIBI scintigraphy in localization of parathyroid tissues; correct localization rate was 87.5 % (7/8) on Met-PET/CT and 50 % (4/8) on MIBI scintigraphy. In semi-quantitative analysis, SUVR was linearly associated with sPTH by linear regression analysis (sPTH = 39.53 × SUVR − 89.84, p = 0.0383). There was a borderline significant difference in pPTH between PH and PA (35.1 vs 204.7 ± 164.0, p = 0.052), while there was no significant difference in sPTH between PH and PA (289 vs 230.4 ± 160.4, p = 0.305).

Conclusions

Met-PET/CT has a potential to be a useful diagnostic modality for preoperative detection and localization of parathyroid tissues with higher sensitivity than MIBI scintigraphy, and for characterization of PA or PH.     

Differentiation of benign and malignant lesions of the tongue by using diffusion-weighted MRI at 3.0?T

Objectives:

Diffusion-weighted MRI (DWI) has been introduced in head and neck lesions and adds important information to the findings obtained through conventional MRI. The purpose of this study was to assess the role of DWI in differentiating benign and malignant lesions of the tongue at 3.0-T field strength imaging.

Methods:

78 patients with 78 lingual lesions underwent conventional MRI and DWI with b-values of 0 and 1000 s mm⁻² before therapy. The apparent diffusion coefficient (ADC) maps were reconstructed, and the ADC values of the lingual lesions were calculated and compared between benign and malignant lesions of the tongue.

Results:

The mean ADC values of the malignant tumours, benign solid lesions and cystic lesions were (1.08 ± 0.16) × 10⁻³, (1.68 ± 0.33) × 10⁻³ and (2.21 ± 0.35) × 10⁻³ mm² s⁻¹, respectively. The mean ADC values of malignant tumours were significantly lower (p < 0.001) than those of benign solid lesions, and the mean ADC values of benign solid lesions were significantly lower (p < 0.001) than those of cystic lesions. Receiver operating characteristic analysis showed that when an ADC value <1.31 × 10⁻³ mm² s⁻¹ was used for predicting malignancy, the highest accuracy of 95.3%, sensitivity of 92.6% and specificity of 97.3% were obtained.

Conclusions:

ADC values of benign and malignant lesions are significantly different at 3.0-T imaging. DWI can be applied as a complementary tool in the differentiation of benign and malignant lesions of the tongue.     

Semi-quantitative contrast-enhanced MR analysis of indeterminate ovarian tumours: when to say malignancy?

Objective:

To evaluate the ability of dynamic post-contrast sequence to specify indeterminate ovarian masses with inconclusive MR features of malignancy. Since management is dramatically different, special focus on the ability to differentiate borderline from invasive malignancy was considered.

Methods:

150 ovarian masses were detected by pelvic ultrasound in 124 patients. Masses had been considered for dynamic post-contrast MRI. We expressed the kinetic parameters (i.e. enhancement amplitude, time peak of maximal uptake and maximal slope) in the form of maximum relative enhancement percentage (MRE%), time of maximal peak of contrast uptake (T_max) and slope enhancement ratio (SER) curves. Histological findings were the gold standard of reference.

Results:

Malignant ovarian masses showed higher MRE% than benign and borderline masses (p < 0.001). T_max was shorter for malignant than benign (p < 0.01) and borderline (p < 0.001) ovarian masses. SER curves were the most suggestive of malignancy with a specificity and accuracy of 85.7% and 84.7%, respectively.

Conclusion:

Dynamic contrast-enhanced MRI could be a specific sequence to differentiate ovarian masses with indeterminate MR morphology with a special discrimination for low potential from invasive ovarian malignancy.

Advances in knowledge:

The study evaluated the diagnostic performance of the individual parameters of dynamic post-contrast MR sequence in evaluating ovarian masses. Management divert between benign, borderline and invasive malignant masses; our work presented a cut-off value for the peak of contrast uptake of 120%, which helped in the differentiation between benign and malignant tumours; the SER curves with Type III (early washout) pattern that was indicative of invasive malignancy was more specific than borderline malignancy.     

Usefulness of SPECT/CT in Parathyroid Lesion Detection in Patients with Thyroid Parenchymal <Superscript>99m</Superscript>Tc-Sestamibi Retention

Purpose

Parathyroid adenoma detection with dual-phase ^99mTc-sestamibi (MIBI) scintigraphy depends on differential MIBI washout from thyroid. However, autoimmune thyroid disease (AITD) may cause MIBI to be retained in the thyroid gland and reduce parathyroid detection. We evaluated the impact of AITD on MIBI thyroid retention and additional benefit of SPECT/CT in these patients.

Methods

Dual phase planar MIBI and SPECT/CT was performed on 82 patients. SPECT/CT was performed immediately after delayed planar scan. Thyroid density (Hounsfield unit, CT-HU) and size were measured on CT component of SPECT/CT. MIBI uptake in early scans and retention in delayed scans were visually graded and correlated with clinical factors and CT findings. Finally, planar and SPECT/CT findings were compared for parathyroid lesion visualization according to thyroid MIBI retention.

Results

In early scan, multivariate analysis showed only thyroid size predicted early uptake. In delayed scan, multivariate analysis showed higher visual grade in early scan, lower CT-HU or AITD were significant predictors for delayed thyroid parenchymal retention. Overall, ten more parathyroid lesions were visualized on SPECT/CT compared to planar scans (57 vs. 47, p?=?0.002). SPECT/CT was especially more useful in patients with thyroidal MIBI retention, as eight out of the ten additional lesions detected were found in patients with thyroid MIBI retention.

Conclusion

AITD is an important factor for MIBI thyroid parenchymal retention on delayed scans, and may impede parathyroid lesion detection. Patients with MIBI retention in the thyroid parenchyma on delayed scans are likely to benefit from an additional SPECT/CT.

     

MRI findings of solitary fibrous tumours in the head and neck region

Objectives:

To analyse the MRI findings of solitary fibrous tumours in the head and neck region.

Methods:

We retrospectively reviewed MR images in eight patients with solitary fibrous tumours proven on histological examination. All the patients underwent conventional MRI, and four patients also underwent dynamic contrast-enhanced MRI and diffusion-weighted imaging in five cases. Image characteristics were analysed.

Results:

All lesions were found as solitary well-defined masses ranging in size from 1.9 to 6.8 cm (mean, 4.1 cm). They were mostly homogeneous and isointense to the muscle on T₁ weighted images and heterogeneous and mildly hyperintense on T₂ weighted images. After gadolinium administration, areas that were mildly hyperintense on T₂ weighted images were strongly enhanced. They were mildly hyperintense on diffusion-weighted imaging. The average tumour-apparent diffusion coefficient values were 0.001 157 ± 0.000 304 9 mm s⁻² compared with the muscle 0.000 760 ± 0.000 265 0 mm s⁻², and there was a statistical difference of p = 0.002. The time–intensity curves exhibited a rapidly enhancing and a slow washout pattern on dynamic contrast-enhanced MRI.

Conclusions:

Solitary fibrous tumours should be considered in cases of heterogeneous hypervascular tumours in the head and neck region. Areas of mild hyperintense intensity on T₂ weighted images that are strongly enhanced after gadolinium injection are suggestive of this diagnosis. Non-restricted diffusion and rapidly enhancing and slow washout pattern time–intensity curves may be additional valuable features.     

The value of intratumoral heterogeneity of 18F-FDG uptake to differentiate between primary benign and malignant musculoskeletal tumours on PET/CT

Objective:

The cumulative standardized uptake value (SUV)–volume histogram (CSH) was reported to be a novel way to characterize heterogeneity in intratumoral tracer uptake. This study investigated the value of fluorine-18 fludeoxyglucose (¹⁸F-FDG) intratumoral heterogeneity in comparison with SUV to discriminate between primary benign and malignant musculoskeletal (MS) tumours.

Methods:

The subjects comprised 85 pathologically proven MS tumours. The area under the curve of CSH (AUC-CSH) was used as a heterogeneity index, with lower values corresponding with increased heterogeneity. As 22 tumours were indiscernible on ¹⁸F-FDG positron emission tomography, maximum standardized uptake value (SUV_max), mean standardized uptake value (SUV_mean) and AUC-CSH were obtained in 63 positive tumours. The Mann–Whitney U test and receiver operating characteristic (ROC) analysis were used for analyses.

Results:

The difference between benign (n = 35) and malignant tumours (n = 28) was significant in AUC-CSH (p = 0.004), but not in SUV_max (p = 0.168) and SUV_mean (p = 0.879). The sensitivity, specificity and accuracy for diagnosing malignancy were 61%, 66% and 64% for SUV_max (optical threshold value, >6.9), 54%, 60% and 57% for SUV_mean (optical threshold value, >3) and 61%, 86% and 75% for AUC-CSH (optical threshold value, ≤0.42), respectively. The area under the ROC curve was significantly higher in AUC-CSH (0.71) than SUV_max (0.60) (p = 0.018) and SUV_mean (0.51) (p = 0.005).

Conclusion:

The heterogeneity index, AUC-CSH, has a higher diagnostic accuracy than SUV analysis in differentiating between primary benign and malignant MS tumours, although it is not sufficiently high enough to obviate histological analysis.

Advances in knowledge:

AUC-CSH can assess the heterogeneity of ¹⁸F-FDG uptake in primary benign and malignant MS tumours, with significantly greater heterogeneity associated with malignant MS tumours. AUC-CSH is more diagnostically accurate than SUV analysis in differentiating between benign and malignant MS tumours.     

Diagnostic Criteria on 18F-FDG PET/CT for Differentiating Benign from Malignant Focal Hypermetabolic Lesions of Parotid Gland

Purpose

We investigated PET/CT diagnostic criteria for differentiating benign from malignant parotid lesions with focal ¹⁸F-FDG uptake.

Methods

The subjects of the study were 272 patients who exhibited focal ¹⁸F-FDG uptake of the parotid gland. Sixty-eight pathologically confirmed parotid lesions from 67 patients were included. The maximum SUV (SUVmax), uptake patterns (homogeneous vs. heterogeneous), size measured by CT, maximum Hounsfield units (HUmax) and margins on CT (well vs. ill defined) of each parotid lesion on PET/CT images were compared with final diagnoses.

Results

Thirty-two parotid lesions were histologically proven to be malignant. There were significant differences in uptake patterns (cancer incidence, heterogeneous:homogeneous = 79.2%:29.5%, p < 0.0001) and margins on CT (cancer incidence, ill:well defined = 84.4%:13.3%, p < 0.0001) between benign and malignant lesions. The cancer risks of parotid lesions were 89.5% with heterogeneous uptake and ill-defined margins, 70.6% with heterogeneous uptake or ill-defined margins (no overlap in subjects) and 9.3% with homogeneous uptake and well-defined margins (p < 0.0001). When any lesion with heterogeneous uptake or ill-defined margins was regarded as malignant, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 90.6% (29/32), 80.6% (29/36), 80.6% (29/36), 90.6% (29/32) and 85.6% (58/68), respectively. For predicting malignancy, combined PET/CT criteria showed better sensitivity, NPV and accuracy than PET-only criteria, and had a tendency to have more accurate results than CT-only criteria. There were no significant differences in SUVmax, size or HUmax between benign and malignant lesions.

Conclusion

Uptake patterns and margins on CT are useful PET/CT diagnostic criteria for differentiating benign from malignant lesions.

Electronic supplementary material

The online version of this article (doi:10.1007/s13139-012-0135-y) contains supplementary material, which is available to authorized users.     

Clinical Usefulness of 18F-fluoride Bone PET

Purpose

¹⁸F-fluoride bone positron emission tomography (PET) has been reported as a useful bone imaging modality. However, no clinical bone PET study had been performed previously in Korea. The authors investigated the usefulness of ¹⁸F-fluoride bone PET in Korean patients with malignant or benign bone disease.

Methods

Eighteen consecutive patients (eight women, ten men; mean age, 55 ± 12 years) who had undergone ¹⁸F-fluoride bone PET for the evaluation of bone metastasis (n = 13) or benign bone lesions (n = 5) were included. The interpretation of bone lesions on ¹⁸F-fluoride bone PET was determined by consensus of two nuclear medicine physicians, and final results were confirmed using combination of all imaging studies and/or clinical follow-up. The analysis was performed on the basis of lesion group.

Results

Thirteen patients with malignant disease had 15 lesion groups, among which seven were confirmed as metastatic bone lesions and eight were confirmed as non-metastatic lesions. ¹⁸F-fluoride bone PET correctly identified six of seven metastatic lesions (sensitivity, 86%), and seven of eight non-metastatic lesions (specificity, 88%). On the other hand, five patients with benign conditions had five bone lesion groups; four were confirmed as benign bone diseases and the other one was confirmed as not a bone lesion. ¹⁸F-fluoride bone PET showed correct results in all the five lesion groups.

Conclusions

¹⁸F-fluoride bone PET showed promising potential for bone imaging in Korean patients with malignant diseases as well as with various benign bone conditions. Therefore, further studies are required on the diagnostic performance and cost-effectiveness of ¹⁸F-fluoride bone PET.     

Characteristic power Doppler sonographic images of tumorous and non-tumorous buccal space lesions

Objectives:

The aim of this study was to evaluate the characteristic power Doppler sonographic images of buccal space tumorous and non-tumorous lesions.

Methods:

48 patients with buccal space lesions were evaluated with greyscale sonography followed by power Doppler sonography with a 12 MHz linear transducer. On greyscale sonography, buccal space lesions were assessed for the boundary (clear or unclear), echogenicity (hypoechoic or isoechoic) and internal architecture (homogeneous or heterogeneous). Power Doppler sonography was performed to evaluate the vascular signals within the buccal space lesions.

Results:

48 lesions were found in the 48 patients; of these 48 lesions, 28 were tumourous and 20 were non-tumourous. In the 28 tumours, 15 cases showed clear boundaries, 15 cases were hypoechoic relative to adjacent tissues and 22 cases presented with a heterogeneous appearance on greyscale sonography. The internal vascularity of 19 tumours was shown using power Doppler sonography. In the 20 non-tumorous lesions, 11 cases showed clear boundaries, 17 cases were hypoechoic relative to adjacent tissues and 13 cases presented with a homogeneous appearance on greyscale sonography. 18 non-tumorous lesions showed no internal vascularity using power Doppler sonography. Logistic multivariate regression analysis between the tumour group and the non-tumorous lesions group demonstrated that the internal architecture (odds ratio = 8.270, p = 0.029) and vascular signals (odds ratio = 17.533, p = 0.003) were significant variables.

Conclusions:

Power Doppler sonography is a useful technique for the differential diagnosis of tumorous and non-tumorous buccal space lesions.     

Evaluation of lung cancer by enhanced dual-energy CT: association between three-dimensional iodine concentration and tumour differentiation

Objective:

To investigate the correlation between iodine concentration of dual-energy CT (DECT) and histopathology of surgically resected primary lung cancers.

Methods:

We reviewed the medical records, post-operative pathological records and pre-operative DECT images of patients who underwent surgical lung resection for primary lung cancer. After injection of iodinated contrast media, arterial and delayed phases were scanned using 140- and 80-kV tube voltages. Three-dimensional iodine concentration (iodine volume) of primary tumours was calculated using lung nodule application software.

Results:

A total of 60 patients (37 males and 23 females; age range, 39–84 years; mean age, 69 years) with 62 lung cancers were analysed. The resected tumours were histopathologically classified into well-differentiated (G1; n = 20), moderately differentiated (G2; n = 29), poorly differentiated (G3; n = 9) and undifferentiated (G4; n = 4) groups by degree of tumour differentiation (DTD). The mean ± standard deviation of iodine volume at the delayed phase was 59.6 ± 18.6 HU in G1 tumours, 46.5 ± 11.3 HU in G2 tumours, 34.3 ± 15.0 HU in G3 tumours and 28.8 ± 6.4 HU in G4 tumours; significant differences were observed between groups (p < 0.001). Univariate logistic regression analysis showed that iodine volumes both at the early and delayed phases were significantly correlated with DTD (p = 0.006 and p = 0.001, respectively), whereas gender, body weight and tumour size were not (p = 0.084, p = 0.062 and p = 0.391, respectively).

Conclusion:

The iodine volume of lung cancers was significantly associated with their DTD. High-grade tumours tended to have lower iodine volumes than low-grade tumours.

Advances in knowledge:

Iodine volume measured by DECT could be a valuable functional imaging method to estimate differentiation of primary lung cancer.     

Differentiation of benign from malignant thyroid nodules with acoustic radiation force impulse technique

Objective:

The aim of our study was to assess the performance of acoustic radiation force impulse (ARFI) imaging to differentiate benign from malignant thyroid nodules.

Methods:

182 patients who needed thyroid surgery were examined. All patients and 50 healthy volunteers underwent ARFI sonoelastography, which quantitatively analysed the elasticity and hardness of the nodule''s centre and periphery.

Results:

ARFI values showed a statistical significance between malignant nodules and benign nodules and common thyroid parenchyma, in both the centre and periphery of nodules (p < 0.01). There was no significant difference between benign nodules and common thyroid parenchyma in either the nodule''s centre or periphery (p > 0.05). There was no significant difference between the nodule''s centre and periphery of the elastic parameters in both the benign and malignant nodules. There was a statistically significant difference among the two areas (the central group and the peripheral group) under the receiver operating characteristic curve, and the optimal model was the peripheral group. For differentiation of malignant from benign nodules, the sensitivity and specificity were 96.3% and 96.2%, respectively, when 2.545 m s⁻¹ was chosen as a cut-off value in the peripheral group.

Conclusion:

ARFI imaging may be helpful to differentiate benign nodules from malignant thyroid nodules. The selecting measurement position is important in ARFI imaging, and it has good diagnostic value in clinical applications.

Advances in knowledge:

This study shows the diagnostic contribution of ARFI imaging in thyroid lesions.Thyroid cancer is the most common endocrine malignancy, and its incidence has increased in recent years.¹ It comprises different clinical and histological features in respect to different treatments.² The diagnostic method for thyroid cancer has very quickly progressed in recent years, but the pre-operative misdiagnosis rate is 40–70%.A newer ultrasound elastography technique called acoustic radiation force impulse (ARFI), which is performed under direct visual guidance, has recently been verified to measure the stiffness of many tissues in vivo, for example in the liver.^3,4 In our study, we investigated the mechanical properties of focal thyroid disease with ARFI. The purposes of this study were to assess the effectiveness of ARFI quantification in the diagnosis of focal thyroid nodules and differentiation of benign from malignant thyroid lesions by quantification of their stiffness.     

Digital breast tomosynthesis within a symptomatic “one-stop breast clinic” for characterization of subtle findings

Objective:

The aim of the study was to evaluate the diagnostic accuracy of combination of full-field digital mammography [two dimension (2D)] and digital breast tomosynthesis [DBT, three dimension (3D)] by comparing the combination with 2D imaging in a symptomatic setting.

Methods:

A retrospective analysis was conducted involving 103 patients who attended symptomatic breast clinics between March 2012 and September 2012. All had subtle signs on 2D images or ultrasound. Mammographic score distribution was compared between 2D imaging and 2D + 3D imaging, followed by comparison with the gold-standard histopathology. Receiver operative characteristic curves and area under curve (AUC) were calculated for 2D imaging and the combination imaging (2D + 3D). SPSS^® v. 21 (IBM Corp., New York, NY; formerly SPSS Inc., Chicago, IL) was used for data analysis with p < 0.05 as statistically significant.

Results:

M3 lesions were reduced from 91 (85.8%) to 18 (16.9%) with the combination imaging. The mean AUC ± 95% confidence interval for 2D images alone was 0.721 (0.662–0.905) and for combined 2D and 3D images was 0.901 (0.765–1.00). The difference in AUCs between the two modalities was 0.180.

Conclusion:

DBT (3D imaging) increases diagnostic accuracy in a symptomatic breast clinic setting and reduces the number of M3 mammograms, when used as an adjuvant to 2D images. Therefore, DBT has the potential to increase workflow efficiency in a symptomatic setting by reducing benign biopsies.

Advances in knowledge:

DBT reduces the number of M3 mammograms when used in the symptomatic breast setting and has the potential to reduce benign biopsies.     

Imaging of acute superior mesenteric artery embolus using spectral CT in a canine model

Objective:

To explore the diagnostic value of single-source dual-energy spectral CT (sDECT) imaging in an acute superior mesenteric artery embolus (SMAE) canine model.

Methods:

Pre-contrast and double-phase contrast-enhanced sDECT were performed before and after embolization in eight SMAE dog models. Monochromatic images of embolized intestine with the best contrast-to-noise ratio (CNR) were obtained and compared with the polychromatic images. CT parameters including attenuation value, iodine content, water content and thickness of the embolized intestinal segments were obtained, and normalized difference in iodine concentration (NDIC) was calculated.

Results:

The CNR in pre-contrast, arterial phase and portal venous phase at 4 h after embolization was 1.11 ± 1.23, 13.50 ± 1.54 and 10.63 ± 3.75, respectively, significantly higher than those of the polychromatic images (p < 0.05). The iodine-based images clearly revealed the embolized intestinal segments, which were highly consistent with the gross findings. The difference in attenuation values between the embolization area and non-embolization area in the monochromatic images was 105.06 ± 35.35 HU, higher than that in the polychromatic images (p < 0.001). The attenuation values and NDIC were significantly decreased at 2 h after embolization, relatively increased at 4 h and gradually decreased at 6 and 8 h. The changing pattern of thickness was similar to that of NDIC over time after embolization.

Conclusion:

sDECT can provide the optimal monochromatic images and allow increased detection rates of lesions. sDECT is a very promising tool for quantitative diagnosis of SMAE.

Advances in knowledge:

Our research provides more quantitative parameters for the assessment of SMAE by sDECT.     

Implications of Three-Phase Bone Scintigraphy for the Diagnosis of Bisphosphonate-Related Osteonecrosis of the Jaw

Purpose

Bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ) is a well-known serious complication of BP treatment. This study was undertaken to evaluate the diagnostic usefulness of three-phase bone scintigraphy in patients with BRONJ.

Methods

Forty-one patients (48 lesions) with clinically proven BRONJ (2 males, 39 females, age 74.3 ± 6.7 years) underwent Tc-99 m HDP bone scintigraphy. Visual interpretation and semiquantitative analysis of uptakes using lesion-to-contralateral uptake ratios during the blood pool phase (BUR) and during the osseous phase (OUR) were performed, and relations were sought between these and various clinical parameters.

Results

Three-phase bone scintigraphy showed increased perfusion and blood pooling in 21 (63.6 %) and 27 (81.8 %) of 33 lesions, respectively. The osseous phase was positive for 45 (93.8 %) of the 48 lesions. Of the four inflammatory clinical parameters of BRONJ [pus discharge, pain, swelling, and erythrocyte sedimentation rate (ESR)], patients with three or more parameters had more positive findings in vascular and blood pool phase images (p = 0.033, p = 0.027). By semiquantitative analysis, patients with a positive ESR had statistically higher BUR and OUR (both p < 0.001). Higher stage BRONJ lesions had higher OUR than lower stage lesions (p = 0.003). In addition, bone scintigraphy revealed three clinically covert BRONJ lesions without bone exposure, and four patients were up-staged based on bone scintigraphy.

Conclusions

Bone scintigraphy provides a relatively sensitive means of detecting BRONJ, so it was helpful for accurate BRONJ staging. Furthermore, increased uptakes in vascular and blood pool phases of three-phase bone scintigraphy were related to the inflammatory activity of BRONJ.     

Impact of Lymphoid Follicles and Histiocytes on the False-Positive FDG Uptake of Lymph Nodes in Non-Small Cell Lung Cancer

Purpose

Although ¹⁸F-fluorodeoxyglucose (FDG) PET/CT has improved the accuracy of evaluating lymph node (LN) staging in non-small cell lung cancer (NSCLC), false-positive results remain a problem. The reason why benign LNs show high FDG uptake is still unclear. The aim of this study was to identify molecular and pathological characteristics of benign LNs showing high FDG uptake.

Materials and Methods

We studied 108 mediastinal LNs of pathologically benign nature obtained from 43 patients with NSCLC who underwent FDG PET/CT and surgery. We measured the following parameters in each LN: maximum standardized uptake value (maxSUV), short diameter, maximum Hounsfield unit (maxHU) value, occupied proportions of lymphoid follicles, histiocytes in extrafollicular space and the degree of glucose transporter 1 (Glut1) expression. We compared the parameters between two LN groups according to maxSUV.

Results

There were 74 LNs showing maxSUV≥3.0 (group 1) and 34 LNs with maxSUV<3.0 (group 2). The size of LN (p < 0.001) and maxHU (p = 0.003) in group 1 was higher than that in group 2. Histologically, the occupied proportions of lymphoid follicles (p = 0.031) or histiocytes (p = 0.004) were higher in group 1. The Glut1 expression of lymphoid follicles (p = 0.035) or histiocytes (p = 0.005) was also higher in group 1.

Conclusion

Lymphoid follicular hyperplasia and histiocyte infiltration associated with Glut1 overexpression are important molecular and pathological mechanisms for false-positive FDG uptake in benign mediastinal LNs in patients with NSCLC.     

A comparison of high b-value vs standard b-value diffusion-weighted magnetic resonance imaging at 3.0?T for medulloblastomas

Objective:

To investigate the utility of diffusion-weighted (DW) MRI using high b-value vs standard b-value for patients with medulloblastoma (MB). Minimum apparent diffusion coefficient (ADC_MIN) values were also compared with tumour cellularity.

Methods:

High and standard b-value DW images were obtained for 17 patients with MB. The number and location of the lesions, signal intensities (SIs), signal-to-noise ratios (SNRs), contrast-to-noise ratios, contrast ratios (CRs) and ADCs of the lesions were compared. Tumour cellularity was also measured and compared with ADC_MIN values.

Results:

All 20 lesions were hyperintense on the DW MR images with high and standard b-values. Four additional lesions were revealed on high b-value, and all 24 lesions were more conspicuous at high b-value. SI, SNR and ADC values for the lesions were lower in the high b-value images than in the standard b-value images. The ADC_MIN value at b = 3000 s mm⁻² was more significantly associated with tumour cellularity than that at b = 1000 s mm⁻². CR values were significantly higher in the high b-value images than in the standard b-value images.

Conclusion:

DW imaging using high b-value may be beneficial for detecting additional, less prominent lesions and may improve the contrast between MB lesions and normal tissue. A stronger inverse correlation with tumour cellularity was identified using the ADC_MIN values at high b-value.

Advances in knowledge:

This study demonstrates the superiority of high b-value DW imaging compared with standard b-value imaging for the detection of MB lesions, especially those with subtle foci.     

Accuracy of CBCT images in the assessment of buccal marginal alveolar peri-implant defects: effect of field of view

Objectives:

To investigate the reliability and accuracy of cone beam CT (CBCT) images obtained at different fields of view in detecting and quantifying simulated buccal marginal alveolar peri-implant defects.

Methods:

Simulated buccal defects were prepared in 69 implants inserted into cadaver mandibles. CBCT images at three different fields of view were acquired: 40 × 40, 60 × 60 and 100 × 100 mm. The presence or absence of defects was assessed on three sets of images using a five-point scale by three observers. Observers also measured the depth, width and volume of defects on CBCT images, which were compared with physical measurements. The kappa value was calculated to assess intra- and interobserver agreement. Six-way repeated analysis of variance was used to evaluate treatment effects on the diagnosis. Pairwise comparisons of median true-positive and true-negative rates were calculated by the χ² test. Pearson''s correlation coefficient was used to determine the relationship between measurements. Significance level was set as p < 0.05.

Results:

All observers had excellent intra-observer agreement. Defect status (p < 0.001) and defect size (p < 0.001) factors were statistically significant. Pairwise interactions were found between defect status and defect size (p = 0.001). No differences between median true-positive or true-negative values were found between CBCT field of views (p > 0.05). Significant correlations were found between physical and CBCT measurements (p < 0.001).

Conclusions:

All CBCT images performed similarly for the detection of simulated buccal marginal alveolar peri-implant defects. Depth, width and volume measurements of the defects from various CBCT images correlated highly with physical measurements.     

The Utility of Segmental Analysis in Cardiac I-123 MIBG SPECT in Parkinson’s Disease

Purpose

Cardiac images using I-123 metaiodobenzylguanidine (MIBG) are widely used to evaluate cardiac sympathetic denervation in Parkinson’s disease (PD). The aim of this study was to evaluate the utility of segmental analysis on cardiac MIBG SPECT in PD patients.

Materials and Methods

In total, 36 patients with PD (n = 26) or essential tremor (ET, n = 10) who underwent MIBG cardiac SPECT were enrolled. The heart-to-mediastinum (H/M) ratios of MIBG uptake were acquired on planar images. For the segmental analysis of SPECT images, we evaluated the summed defect score (SDS) using a 17-segment model. The diagnostic abilities of H/M ratios and segmental parameters on MIBG SPECT were assessed by ROC curve analysis.

Results

The H/M ratios were significantly lower in PD than in ET patients (p < 0.05). On segmental analysis, SDS was significantly higher in PD patients than in the ET group (7.04 ± 4.09 vs. 2.90 ± 2.80; p = 0.006). The defect score of the anteroseptal region showed a significant difference between the groups (p = 0.002). The ROC analysis suggested only SDS (AUC = 0.785, p = 0.0003) and defect scores in the anteroseptal (AUC = 0.800, p < 0.0001) and inferior (AUC = 0.667, p = 0.013) regions showed significant diagnostic ability to differentiate PD from ET.

Conclusions

Segmental parameters from cardiac MIBG SPECT images can provide additional information to differentiate PD from ET patients. Beyond H/M ratios from planar images, we recommend an MIBG SPECT study to evaluate sympathetic denervation in PD.     

Comparison between DICOM-calibrated and uncalibrated consumer grade and 6-MP displays under different lighting conditions in panoramic radiography

Objectives:

To compare observer performance in the detection of anatomical structures and pathology in panoramic radiographs using consumer grade with and without digital imaging and communication in medicine (DICOM)-calibration and 6-megapixel (6-MP) displays under different lighting conditions.

Methods:

30 panoramic radiographs were randomly evaluated on three displays under bright (510 lx) and dim (16 lx) ambient lighting by two observers with different years of experience. Dentinoenamel junction, dentinal caries and periapical inflammatory lesions, visibility of cortical border of the floor and pathological lesions in maxillary sinus were evaluated. Consensus between the observers was considered as reference. Intraobserver agreement was determined. Proportion of equivalent ratings and weighted kappa were used to assess reliability. The level of significance was set to p < 0.05.

Results:

The proportion of equivalent ratings with consensus differed between uncalibrated and DICOM-calibrated consumer grade displays in dentinal caries in the lower molar in dim lighting (p = 0.021) and between DICOM-calibrated consumer grade and 6-MP display in bright lighting (p = 0.038) for an experienced observer. Significant differences were found between uncalibrated and DICOM-calibrated consumer grade displays in dentinal caries in bright lighting (p = 0.044) and periapical lesions in the upper molar in dim lighting (p = 0.008) for a less experienced observer. Intraobserver reliability was better at detecting dentinal caries than at detecting periapical and maxillary sinus pathology.

Conclusions:

DICOM calibration may improve observer performance in panoramic radiography in different lighting conditions. Therefore, a DICOM-calibrated consumer grade display can be used instead of a medical display in dental practice without compromising the diagnostic quality.     

A cone beam CT investigation of ponticulus posticus and lateralis in children and adolescents

Objectives:

To determine the prevalence and pathogenesis of ponticulus posticus (PP) and ponticulus lateralis (PL) in children and adolescents.

Methods:

Cone beam CT scans of 576 patients were examined for PP and PL. The patients were divided into three age groups: 10 years and younger, 11–13 years and 14 years and older. Ponticulus formation was categorized as absent, partial or complete. Gender, race and location (right, left or bilateral) were recorded. Data were analysed with the χ² test, with significance at p < 0.050. Institutional review board approval was granted.

Results:

Overall prevalence of PP was 26.2%, with complete lesions in 10.4%. The frequency of PP was greater in patients aged 14 years and older (p ≤ 0.038). The occurrence of complete PP was greater in patients aged 11 years and older (p = 0.028). Lesions were more common in males (p = 0.014) and in blacks compared with other non-white races (p = 0.035). Bilateral PP was more common than right-sided lesions (p = 0.008) and more frequent in the oldest cohort (p = 0.006). Overall prevalence of PL was 6.1% (3.0% complete), with no differences between age groups, genders, races or by location.

Conclusions:

PP is not uncommon even in the first decade and increases in frequency, completeness of calcification and numbers in mid-adolescence. It appears to be more common in males and in blacks. PP may be a congenital osseous anomaly of the atlas that mineralizes at various times. PL is less frequent with no demographic predilections.