Can three-dimensional pelvimetry using low-dose stereoradiography replace low-dose CT pelvimetry?

Radiologically anatomic measurement analysis for the third sacral foramen and an efficient implantation protocol for sacral neuromodulation

AIMS

To define radiologically anatomic measurements for the S3 foramen and develop an efficient and straightforward implantation protocol for sacral neuromodulation (SNM) in a southern Chinese population.

METHODS

We retrospectively reviewed 793 adults without sacrococcygeal abnormalities or bony injury. We generated CT-derived three-dimensional volumetric models and collected radiologically anatomic measurements of S3 foramen. A multiple generalized linear regression model was applied to evaluate implantation protocol for SNM.

RESULTS

Height, weight, and sacral height were significantly different between enrolled patients based on sex (p < 0.001 for all), while age and sacral width were similar. The measurements L1, L2, A1, and A2 on both sides were similar, while based on sex, those of L1, A1, A2 showed significant differences [7.02 ± 0.90 (M) vs. 6.10 ± 0.99 cm (F) (p < 0.001); 83.05 ± 6.23 (M) vs. 82.08 ± 7.53° (F) (p = 0.005); and 13.31 ± 5.69 (M) vs. 11.97 ± 4.91° (F) (p < 0.001), respectively]. The multiple generalized linear regression model demonstrated that sex was a common independent factor for estimating L1, L2, A1, A2, while the consistency rate between the estimated model and actual measurements was poor. The measurements L1, L2, A1, and A2 were approximately 7.0 cm (M) versus 6.1 cm (F), 1.8 cm (M) versus 1.8 cm (F), 83° (M) versus 82° (F), and 13° (M) versus 12° (F), respectively.

CONCLUSIONS

This retrospective study indicates that the radiologically anatomic measurements for the S3 foramen have unique characteristics. Our study provides an efficient and straightforward implantation protocol for SNM, improving its use in China.

Postoperative spino-pelvic stereoradiography to predict adjacent segment disease

PURPOSE

The purpose of this study was to identify sagittal spinopelvic parameters predictive of adjacent segment disease (ASD) on postoperative whole spine weight-bearing stereoradiography.

MATERIALS AND METHODS

A total of 84 patients with previous spinal fusion surgery and documented radiological follow-up with early weight-bearing postoperative whole spine stereoradiography (EOS® Imaging System) were retrospectively included. A pathological group of 42 patients (9 men, 33 women; mean age, 63.1±11.5 [SD] years) who developed documented ASD (mean follow-up, 76.75 months; range: 31.5-158.5 months) was compared with a control group of 42 asymptomatic patients (7 men, 35 women; mean age, 60.9±11.8 [SD] years) (mean follow-up, 115 months; range: 60-197 months) based on sagittal balance evaluation and routinely used spino-pelvic parameters. Comparisons were made using uni- and multivariate analyses.

RESULTS

At univariate analysis, patients with ASD had an anteriorly displaced sagittal vertical axis (CAM plumb line) and an inadequate lumbar lordosis (LL) in reference to pelvic incidence (PI) compared to controls. They also had higher C7 slope and C2-C7 offset. At multivariate analysis, C2-C7 offset (OR=1.152; 95% CI: 1.056-1.256; P=0.001) and a lack of LL (OR=5.063; 95% CI: 1.139-22.498; P=0.033) were significantly associated with ASD.

CONCLUSION

Anterior cervical imbalance, reflected by an increase in C2-C7 offset and insufficient restoration of LL are postoperative predictive factors of ASD on stereoradiography.

[Development of CT Pelvimetry Using Deep Learning Based Reconstruction]

PURPOSE

X-ray pelvimetry is typically performed for the diagnosis of the cephalopelvic disproportion (CPD). The purpose of this study was to assess the utility of new computed tomography (CT) reconstruction "deep learning based reconstruction (DLR) " in ultra-low dose CT pelvimetry.

METHOD

CT pelvimetry was performed 320-row CT. All CT images were reconstructed with and without DLR and transferred for workstation to processing martius and guthmann view. Radiologist and obstetrician-gynecologist subjectively ranked overall image quality of each CT image from the best to the worst. Exposure dose of the CT pelvimetry used a following calculated value, displayed CT dose index (CTDI) _vol multiplied by measured value using the thimble chamber and pelvic phantom, and of the X-ray pelvimetry used Japan-Diagnositic Refernce Levels 2015 as a reference, were compared.

RESULT

3D images obtained from CT pelvimetry with DLR showed accurate biparietal diameter and obstetric conjugate as compared to without DLR. Radiation dose of CT pelvimetry is 0.39 mGy, of X-ray pelvimetry is 1.18 mGy, respectively. Conculusion: Although the visualizing high contrast object, such as bone morphology, is likely to reduce exposure dose in CT examination generally, DLR enable to further dose reduction to keep image quality. 3D image processing from CT pelvimetry solves the problem of expansion rate in X-P pelvimetry and provide accurate measurements. Furthermore, CT pelvimetry can undergo more comfortable position for Pregnant Woman in Labor.

How reproducible are classical and new CT-pelvimetry measurements?

PURPOSE

The objective of this study was to assess the reliability and reproducibility of existing and new computed tomography (CT)-pelvimetry measurements.

MATERIAL AND METHODS

A retrospective cohort study of 63 women with a mean age of 33.9±5.2 (SD) years (range: 19-49 years) was conducted. Classical pelvimetry measurements were collected including the obstetric conjugate (OC), median transverse diameter (MTD), and interspinous diameter (ISD). Additionally, we used multiplanar reconstruction (MPR) mode to define two oblique planes: inlet pelvic plane (IPP) and mid-pelvic plane (MPP) and measure new pelvic parameters, including anteroposterior (APD), transverse diameters and circumference of both IPP and MPP (inletAPD, inletMTD, inletCIRC and midAPD, ISD, midCIRC, respectively). The reproducibility (intra- and inter-observer) of our results were assessed. Multivariate analyses using principal component analysis and clustering methods were conducted to analyze the association between pelvimetry measurements and identify patient sub-groups.

RESULTS

All linear measurements (OC, inletAPD, MTD, inletMTD, midAPD, and ISD) showed statistically "almost perfect" intra- and inter-observer correlation coefficients (range: 0.924-0.980). Circumferences (inletCIRC and midCIRC) showed statistically "almost perfect" intra- (range: 0.847-0.857) and inter-observer correlation coefficients (range: 0.923-0.957). The measurement of 6 pelvimetric parameters allowed determining three groups of pelvis size.

CONCLUSION

New pelvic measurements have excellent reproducibility and are similar to the classical measurements, based on the MPR analysis of CT planes adjusted to the inner bony pelvis.