Diagnostic performance of SPECT-CT imaging in unilateral condylar hyperplasia

Proportional Condylectomy Using a Titanium 3D-Printed Cutting Guide in Patients with Condylar Hyperplasia

BACKGROUND

The purpose of the study was to describe proportional condylectomy in patients with condylar hyperplasia using a titanium 3D-printed ultrathin wire mesh cutting guide placed below the planned bone resection.

METHODS

Eight patients with condylar hyperplasia underwent proportional condylectomy using an ultrathin titanium 3D-printed cutting guide placed below the planned bone resection. The placement of the guide was facilitated by the incorporation of anatomical landmarks. The accuracy of bone resections guided by such devices was evaluated on postoperative radiographs. The mean postoperative follow-up was 30 months.

RESULTS

Surgery could be performed in all patients in the same manner as virtually planned. The fitting accuracy of the cutting guides was judged as good. Postoperative radiographs revealed that the virtually planned shape of the newly formed condylar head after condylectomy could be achieved.

CONCLUSIONS

In conclusion, the use of virtual computer-assisted planning and CAD/CAM-based cutting guides for proportional condylectomy in unilateral condylar hyperplasia of the mandible offers high accuracy and guarantees very predictable results.

Diagnostic Efficacy of Bone SPECT Techniques in Differentiating Unilateral and Bilateral Condylar Hyperplasia

Objectives: This analytical cross-sectional study evaluates diagnostic approaches for active condylar hyperplasia using bone SPECT techniques. Methods: it was compared the effectiveness of relative activity assessments between condyles and quantitative analysis using the condyle/clivus ratio. Results: This study's findings reveal that the condyle/clivus ratio method significantly outperforms the relative uptake method, achieving a sensitivity of 90.1% (95% CI: 84.1-94) compared to 40.7% (95% CI: 33.5-48.2), and a specificity of 77.1% (95% CI: 67.4-85) versus 72.9% (95% CI: 62.9-81.5). The condyle/clivus ratio also showed a more favorable negative likelihood ratio of 0.13 compared to 0.82 for relative uptake, and a higher area under the curve (AUC) of 0.8360 versus 0.5679. Statistically significant differences were noted (p = 0.0001). The condyle/clivus ratio method effectively identifies affected condyles in unilateral and bilateral condylar hyperplasia cases. Conclusions: This study emphasizes the importance of incorporating comprehensive clinical evaluations and imaging modalities for assessing condylar growth activity, underscoring the need for tailored reference values in different populations to ensure reliable diagnostic interpretations.

Eagle syndrome: tissue characteristics and structure of the styloid process

Eagle syndrome is a bone disease where elongation of the styloid process leads to throat and neck pain, and in severe cases neurovascular symptoms such as syncope and neuralgia. The pathophysiology of Eagle syndrome is poorly understood with various theories having been proposed how this elongation is caused. To better understand the pathophysiology, we performed a work-up in 6 patients presenting with Eagle syndrome. Patients mainly presented with pain on turning the neck (100%), foreign body sensation (67%), tension in the neck (67%), and dysphagia (50%). The typical length of the styloid process ranges from 25 to 30 mm; however, [18F]NaF (sodium fluoride) PET/CT showed elongated styloid processes with an average length of 52.1 ± 15.6 mm (mean ± SD) with increased turnover at the base of one of the styloid processes. The removed styloid processes were further examined by histology, micro-CT, quantitative backscatter electron imaging (qBEI), Fourier transform infrared spectroscopy (FTIR), and circularly polarized light imaging. Histology revealed one case of a fractured styloid process healing through callus formation and one case of pseudarthrosis. Bone mineral density and mineralization was similar in the styloid processes when compared to cortical bone samples derived from the mandibular bone of different patients. Circular polarized light microscopy showed a collagen orientation in the styloid process comparable to the cortical bone samples with a distinct separation of collagen structure between the mineralized structure and the surrounding soft tissue with FTIR analysis demonstrating a typical composition of bone. This altogether suggests that the elongated styloid processes in Eagle syndrome are mature bone, capable of endochondral repair, possibly growing from the base of the process through endochondral ossification, rather than being a form of secondary calcification of the stylohyoid ligament as previously postulated.

From SPECT/CT towards absolute quantification? - the case of unilateral condylar hyperplasia of the mandible

BACKGROUND

Unilateral condylar hyperplasia (UCH) of the mandible is a rare condition characterized by asymmetric growth of the mandibular condyles. Bone scintigraphy with SPECT(/CT) is commonly used to diagnose UCH and guide treatment. Still, varying results have been reported using the traditional threshold of 55%:45% in relative tracer uptake. While absolute quantification of uptake on SPECT/CT could improve results, optimal correction and reconstruction settings are currently unknown.

METHODS

Three anthropomorphic phantoms representing UCH were developed from patient CT volumes and produced using 3D printing technology. Fillable spherical inserts of different sizes (Ø: 8-15 mm) were placed in the condylar positions representing symmetrical and asymmetrical distributions. Recovery coefficients were determined for SPECT/CT using various reconstruction corrections, including attenuation and scatter correction (ACSC), resolution modeling (RM), and partial volume correction (PVC) using phantom measurements. Uptake ratios between condyles and condyle to clivus were evaluated. Finally, the impact of these correction techniques on absolute activity and diagnostic accuracy was assessed in a retrospective patient cohort for the diagnostic threshold of 55%:45%.

RESULTS

The activity was only partially recovered in all spherical inserts (range: 22.5-64.9%). However, RM improved relative recovery by 20.2-62.3% compared to ACSC. In the symmetric phantoms, the 95% confidence interval (CI) of condyle ratios included the diagnostic threshold (57.6%:42.4%) for UCH when using ACSC potentially leading to false positives, but not for ACSCRM datasets. Partial volume corrections coefficients from the NEMA IQ phantom was positionally dependent, with improvements seen performing PVC using coefficients derived from anthropomorphic phantoms. Retrospective application in a patient cohort showed only a weak linear correlation (R²: 0.25-0.67) and large limits of agreement (9.6-12.5%) between different reconstructions. Up to 44% of patients were reclassified using the 55%:45% threshold. Using clinical outcome data, ACSCRM had highest sensitivity (91%; 95% CI 59-100%) and specificity (66%; 95% CI 47-81%), significantly improving specificity (P = 0.038).

CONCLUSIONS

Anthropomorphic phantoms were shown to be essential in determining optimal settings for acquisition, reconstruction, and analysis. SPECT/CT reconstructions with attenuation and scatter correction and resolution modeling are recommended and could improve specificity when using the 55%:45% threshold to assess condylar growth.

Accuracy of skeletal scintigraphy for the evaluation of mandibular growth disorders: a systematic review

Bone scans, reflecting blood flow and metabolic activity in a region of interest, are frequently used to evaluate mandibular growth disorders. Increased uptake is a non-specific finding and can occur as a result of multiple causes. The correlation between radioactive tracer uptake and growth activity has not been consistently demonstrated. The aim of this study was to assess the accuracy of planar skeletal scintigraphy (SS), single-photon emission computed tomography (SPECT), and SPECT with computed tomography (CT) images (SPECT/CT) in detecting abnormal mandibular growth activity compared to clinical and radiographic/tomographic methods (reference standard) and histologic findings. A systematic review was conducted following the PRISMA guidelines. Sensitivity, specificity, and accuracy were calculated for planar SS, SPECT, and SPECT/CT. Compared to the reference standard, SPECT/CT had the best diagnostic accuracy (76.5% sensitivity, 90.4% specificity, 83.2% accuracy), followed by planar SS (81.8% sensitivity, 84.5% specificity, 83.0% accuracy) and SPECT (77.7% sensitivity, 72.4% specificity, 74.5% accuracy). The results of this study indicate that SPECT/CT has the best clinical correlation, but the certainty of the evidence is low. The differences in sensitivity and specificity between the three index tests were not clinically significant. The three tests can be useful, with only a small difference in their diagnostic value. Histopathology was found not to be satisfactory as a reference standard.

Assessment of unilateral condylar hyperplasia with quantitative SPECT/CT

Purpose

The current study aimedto assess condylar activityin patients with unilateral condylar hyperplasia (UCH) with quantitative SPECT/CT.

Patients and methods

This retrospective study included patients with UCH who underwent quantitative SPECT/CT. SPECT analysis and quantification of SPECT/CT were performed, and the maximum count per pixel and SUVmax of either side of the condyles were calculated.

Results

39 patients were included in the analysisand classified into three subgroups according to the percentile differential right-left ratio: inactive group, left active (LA) group, and right active (RA) group. Totally, the SUVmax of the affected side is significantly higher than the unaffected side (active:5.93 ± 2.43 vs inactive:3.62 ± 1.76, P < 0.001), SUVmax-based ratios correlated well with the ratios based on maximum count (R = 0.944, P < 0.001). ROC analysis showed poorSUVmaxperformance in differentiation between theactive condyles and the inactive condyles due to the lower area under the curve (AUC) (0.588). In subgroup analysis, the affected side is significantly higher than the unaffected side in active groups with SUVmax, no significant difference was found between the active sides or the inactive sides of active groups. Interestingly, the SUVmax of the left side was statistically higher than that of the right sidein the inactive group (P = 0.01),while the left side of the right active group has significantlylower activitythan that in the inactive group, meanwhile,the right side showed no significant difference. Furthermore, each side showed no significant difference between the left active group and the inactive group.

Conclusions

SUVmax is not an optimal measurement effectively used to evaluate active condyles. However, SUV ratios correlated well with the count ratios, and the left side of condyles showed a peculiar feature in condyle growth status reflected in radioactivity quantified with SPECT/CT, which needs further study to determine the role in the development of the UCH.

Evaluation of optimal single-photon emission computed tomography reference value and three-dimensional mandibular growth pattern in 54 Chinese unilateral condylar hyperplasia patients

BACKGROUND

The research aimed to evaluate the optimal Single-Photon Emission Computed Tomography (SPECT) cut-off value in differentiating condylar growth activeness, to observe 3-dimensional (3D) mandibular growth pattern, and to explore the potential correlation between 3D measurement parameters and SPECT uptake ratios in Chinese unilateral condylar hyperplasia (UCH) patients.

METHODS

 Data of fifty-four Chinese UCH patients were analyzed retrospectively. All patients underwent SPECT within 1 month before or after the first CT examination (CT1); and received a second CT examination at least 12 months later (CT2). Data from CT scans were analyzed by comparing bilateral differences between CT1 and CT2. The sensitivity and specificity of SPECT were calculated by the receiver operating characteristic (ROC) curve. Pearson's correlation analysis was performed to investigate whether the mandibular growth was correlated with SPECT value.

RESULTS

SPECT had a sensitivity of 68.00% and a specificity of 72.41%, with an area under the ROC curve being 0.709. The optimal SPECT cut-off value for evaluating condylar activity has been determined to be 13%. In patients with an active growing condyle, there was a significant increase in Co-Gn and Co-Go, but not in Go-Gn, Go-MF, or MF-Gn. Pearson's correlation analysis revealed no correlation between 3D measurement parameters and differences in relative condylar uptake ratios.

CONCLUSION

SPECT showed good diagnostic performance in UCH with the cut-off value of 13%. For those with an active growing condyle, the mandible grows diagonally and vertically, while the relative condylar uptake ratio was not directly related to mandibular growth.