Assessment of enthesopathy in conventional pelvis radiography: Another tool for spondyloarthritis diagnosis beyond sacroiliitis.

INTRODUCTION/OBJECTIVES: Enthesitis is a cardinal feature of spondylarthritis (SpA), and the pelvis is a common site of enthesitis. This study aimed to establish the association between pelvic enthesis involvement on pelvic X-ray and SpA diagnosis through a radiographic enthesis index (REI) and to assess the reliability and accuracy of this REI. MATERIALS AND METHODS: The participants were SpA patients and a control group composed of patients with chronic lumbar pain without SpA. Three blinded observers assessed each pelvic radiography three times. Three zones were used: Zone I (ZI), the iliopubic ramus; Zone II (ZII), the pubic symphysis, and Zone III (ZIII), the ischiopubic ramus. A grading system was created from 0 to 3 [Grade 0, normal; Grade 1, minimal changes (subcortical bone demineralization and/or periosteal wishkering, seen as radiolucency and trabeculation of the cortical bone upon tendon insertion); Grade 2, destructive changes (Grade 1 findings and erosions at the enthesis site); and Grade 3, findings of Grade 2 plus >2 mm whiskering out of the cortical bone) for the REI. The sum of the results of the three zones was called the total REI. For statistical analysis, we used the weighted kappa statistic adjusted for prevalence and bias using Gwet's agreement coefficient. RESULTS: We enrolled 161 patients, 111 of them with SpA (39.6 % with axial SpA and 47.7 % with peripheral SpA) and 50 without SpA. In the SpA group, 36.7 % and 25.7 % had REI Grades 2 and 3 in ZIII, respectively, while only 6 % of the controls had these grades. For ZI, the frequency of Grades 1 to 3 was 42.3 % in the SpA group (8.1 %, 14.4 %, and 19.8 %, respectively), compared to only 2 % in the controls. ZII was unaffected in most of the patients with SpA (82.9 %) and in the controls (98 %). In the control group, Grade 0 was the most common REI grade in all three zones. The agreement was almost perfect for each zone and between the independent readers. The ROC-curve analysis showed that the highest performance areas were the total REI, ZIII, and ZI. Most (75 %) of the SpA patients without sacroiliitis on X-ray were REI-positive. The sensitivity of the REI for SpA diagnosis was 82 %, while the sensitivity of sacroiliitis on X-ray was 38.7 %. CONCLUSIONS: The assessment of pelvic enthesis using the REI on pelvic radiography may be useful for SpA diagnosis. Total REI, ZIII, and ZI had the highest accuracy and almost perfect reliability. The REI is especially helpful in patients without sacroiliitis on imaging.

Accuracy and Clinical Impact of Persistent Disease Diagnosed on Diffusion-Weighted Imaging and Accuracy of Pelvic Nodal Assessment on Magnetic Resonance Imaging for Squamous Cell Carcinoma of the Anus in the 6-Month Interval Post Chemoradiotherapy.

PURPOSE: To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) in the 6-month interval post chemoradiation therapy (CRT) in determining persistent disease and whether persistent diffusion restriction on DWI at 6 months is associated with overall survival; and secondarily, to investigate the accuracy of pelvic lymph node assessment on T2-weighted imaging and DWI in the 6-month interval post CRT, in patients with squamous cell carcinoma of the anus. METHODS AND MATERIALS: This retrospective study included patients with squamous cell carcinoma of the anus who underwent CRT followed by restaging rectal MRI from January 2010 to April 2020, with ≥1 year of follow-up after CRT. DW images were qualitatively evaluated by 2 junior and 2 senior abdominal radiologists to determine anal persistent disease. The reference standard for anal persistent disease was digital rectal examination/endoscopy and histopathology. Diagnostic performance was estimated using sensitivity, specificity, negative predictive value, and positive predictive value. Survival outcomes were evaluated via Kaplan-Meier analysis, and associations between survival outcomes and DWI status were tested for significance using the log-rank test. Additionally, DW and T2-weighted images were evaluated to determine lymph node status. RESULTS: Among 84 patients (mean age, 63 ± 10.2 years; 64/84 [76%] female), 14 of 84 (17%) had confirmed persistent disease. Interreader agreement on DWI between all 4 radiologists was moderate (Light's κ = 0.553). Overall, DWI had a sensitivity of 71.4%, specificity of 72.1%, positive predictive value of 34.5%, and negative predictive value of 92.5%. Patients with a negative DWI showed better survival than patients with a positive DWI (3-year overall survival of 92% vs 79% and 5-year overall survival of 87% vs 74%), although the difference did not reach statistical significance (P = .063). All patients with suspicious lymph nodes (14/14, 100%) showed negative pathology or decreased size during follow-up. CONCLUSIONS: At 6 months post CRT, DWI showed value in excluding anal persistent disease. Persistent diffusion restriction on DWI was not significantly associated with overall survival. Pelvic nodal assessment on DWI and T2-weighted imaging was limited in predicting persistent nodal metastases.

Assessment of fetal radiation exposure in pregnant women undergoing computed tomography and rotational angiography examinations for pelvic trauma.

This study aimed to assess fetal radiation exposure in pregnant women undergoing computed tomography (CT) and rotational angiography (RA) examinations for the diagnosis of pelvic trauma. In addition, this study aimed to compare the dose distributions between the two examinations. Surface and average fetal doses were estimated during CT and RA examinations using a pregnant phantom model and real-time dosemeters. The pregnant model phantom was constructed using an anthropomorphic phantom, and a custom-made abdominal phantom was used to simulate pregnancy. The total average fetal dose received by pregnant women from both CT scans (plain, arterial and equilibrium phases) and a single RA examination was ~60 mGy. Because unnecessary repetition of radiographic examinations, such as CT or conventional 2D angiography can increase the radiation risk, the irradiation range should be limited, if necessary, to reduce overall radiation exposure.

Improved compact representation method for Monte Carlo phase spaces.

Phase space files used in particle Monte Carlo simulations can be large, and thereby awkward to distribute and slow to load into memory. To circumvent this, compact source models and phase space representations have been developed. In this study, the aim is to increase the versatility of a previously presented method, based on principal component analysis whitening, by evaluating several modifications to the method on simulated cone-beam computed tomography projection images. Scaling the phase space components before whitening was seen to give the largest improvement and allowed for accurate modelling of phase spaces with a shifted detector and/or a bowtie filter present, configurations where the original method struggled. The modified method reproduced results using the original phase space to within a few percent both in energy fluence on the detector and in simulated projection and scatter images of a patient pelvis, without obvious position-dependence of the errors. Hence, the modified method was deemed sufficiently accurate for most applications relying on cone-beam computed tomography simulations. The final aim is to use the more versatile method for a broader range of phase space-based applications such as linear accelerator beam simulations and room shielding calculations.

Novel method for calculating the effective dose using size-specific dose estimates conversion factors in abdomen-pelvis computed tomography.

We propose a novel method for calculating the effective dose that closely reflects the individual attenuation, utilizing two conversion coefficients. A total of 180 adult patients who underwent abdomen-pelvis computed tomography were categorized into six groups based on sex and body type. The effective dose was calculated by multiplying the dose-length product with the effective dose conversion coefficient and the size-specific dose estimate conversion factor. The effective dose calculated using a simulation-based dose calculator (WAZA-ARI) was employed as the reference value. The following values, obtained through both methods, were compared within each category: distribution of the effective dose, median effective dose, and relative difference in median effective dose across additional body mass index (BMI) categories. For male patients, no significant disparity was observed in the median effective doses calculated using the two methods. The relative differences in median effective doses across additional BMI categories ranged from - 5 to 6%. Conversely, among female patients, the median effective dose calculated using our method slightly undercut that calculated using WAZA-ARI, with relative differences ranging from - 16 to - 9%. Additionally, relative differences in median effective dose across additional BMI categories ranged from - 18 to - 7%. The median effective dose differed slightly depending on the calculation method because of the different reference phantoms applied in dose calculations. Our proposed method is sensitive to individual size and helps compute a size-specific effective dose.

AP Radiographic Assessment of the Pediatric Pelvis for Developmental Dysplasia of the Hip.

Mastering the art of roentgenographic analysis of the pediatric AP pelvis is paramount in the evaluation of developmental dysplasia of the hip. Understanding the normal radiographic development and the age-dependent changes in normal values allows assessment for pathologic changes. The goal of improving the analysis of the AP pelvis is to increase early detection of disease, assess progress toward normal values, and precisely follow the effects of treatment to improve clinical outcomes.

Diagnostic accuracy of pelvis multiparametric MRI against CT virtual hysterosalpingography: a prospective study of tubal patency through female infertility assessment.

OBJECTIVE: To evaluate the diagnostic accuracy of MRI-hysterosalpingogram (HSG) with semiquantitative dynamic contrast-enhanced perfusion, against the virtual multislice CT hysterosalpingogram (VHSG) as a reference standard. METHODS AND MATERIALS: In this prospective study, 26 women (age >18 years) searching for infertility causes and with VHSG physician request. Thereafter, the assessment performance of both techniques was determined by two reader analyses. k statistics were used for the assessment of tubal patency. Receiver operating characteristic (ROC) analysis was used to compare the capability for tubal patency assessment between both exams on a per-patient and per-tube basis. The McNemar test was used to compare the diagnostic accuracy measures. RESULTS: Tubal patency, uterine morphological, ovarian, and extrauterine abnormalities were evaluated through both exams in all 26 women. There was no significant difference between diagnostic performance measurements between the methods. The ROC curve of VHSG was 0.852 for both per-patient and per-tube analyses, and one and 0.938 for MRI-HSG. Sensitivity and specificity for per-patient and per-tube for VHSG were 95.2 and 97.7, 80 and 87.5%, and for MRI-HSG 100% for both analyses and 100 and 87.5%, respectively. CONCLUSION: This study demonstrates the feasibility of diagnosing tubal patency through MRI, using a semi-quantitative dynamic contrast-enhanced perfusion sequence, and the satisfactory diagnosing of the uterine morphology, ovarian abnormalities, and ovarian and deep endometriosis. ADVANCES IN KNOWLEDGE: Multiparametric MRI with a perfusion real-time sequence as a HSG method can be used in the evaluation not only for uterine and ovarian abnormilities but also tubal patency.

Assessment of a single-pass venous phase CT chest, abdomen and pelvis and dual-energy CT in general oncology outpatients.

INTRODUCTION: This study assessed replacing traditional protocol CT-arterial chest and venous abdomen and pelvis, with a single-pass, single-bolus, venous phase CT chest, abdomen and pelvis (CAP) protocol in general oncology outpatients at a single centre. METHODS: A traditional protocol is an arterial phase chest followed by venous phase abdomen and pelvis. A venous CAP (vCAP) protocol is a single acquisition 60 s after contrast injection, with optional arterial phase upper abdomen based on the primary tumour. Consecutive eligible patients were assessed, using each patient's prior study as a comparator. Attenuation for various structures, lesion conspicuity and dose were compared. Subset analysis of dual-energy (DE) CT scans in the vCAP protocol performed for lesion conspicuity on 50 keV virtual monoenergetic (VME) images. RESULTS: One hundred and eleven patients were assessed with both protocols. Forty-six patients had their vCAP scans using DECT. The vCAP protocol had no significant difference in the attenuation of abdominal structures, with reduced attenuation of mediastinal structures. There was a significant improvement in the visibility of pleural lesions (p < 0.001), a trend for improved mediastinal nodes assessment, and no significant difference for abdominal lesions. A significant increase in liver lesion conspicuity on 50 keV VME reconstructions was noted for both readers (p < 0.001). There were significant dose reductions with the vCAP protocol. CONCLUSION: A single-pass vCAP protocol offered an improved thoracic assessment with no loss of abdominal diagnostic confidence and significant dose reductions compared to traditional protocol. Improved liver lesion conspicuity on 50 keV VME images across a range of cancers is promising.

EFFECT OF PELVIC LEAD SHIELD ON ORGAN DOSES IN POSTERO-ANTERIOR CHEST RADIOGRAPHY.

Lead shields are commonly used in X-ray imaging to protect radiosensitive organs and to minimise patient's radiation dose. However, they might also complicate or interfere with the examination, and even decrease the diagnostic value if they are positioned incorrectly. In this study, the radiation dose effect of waist half-apron lead shield was examined via Monte Carlo simulations of postero-anterior (PA) chest radiography examinations using a female anthropomorphic phantom. Relevant organs for dose determination were lungs, breasts, liver, kidneys and uterus. The organ dose reductions varied depending on shield position and organ but were negligible for properly positioned shields. The shield that had the largest effective dose reduction (9%) was partly positioned inside the field of view, which should not be done in practice. Dose reduction was practically 0% for properly positioned shields. Therefore, the use of lead shield in the pelvic region during chest PA examinations should be discontinued.

The effect of pelvic ring rotation and tilt on the radiographic teardrop distance: an important consideration in the assessment of dynamic displacement on stress radiographs.

PURPOSE: The purpose of this study was to determine the effect of rotation and tilt on the radiographic teardrop distance (TD) on anteroposterior (AP) pelvis radiographs. METHODS: Radiographic examination of a pelvis models was conducted utilizing increasing degrees of beam rotation and tilt on portable C-arm fluoroscopy. The TD, x-plane rotation (symphyseal-mid-sacrum distance (SMS)), and y-plane tilt (sacroiliac joint-symphysis distance (SIS)) were measured by four independent observers. Interobserver reliability was assessed using intraclass correlations. RESULTS: TD was altered by less than 2 mm with up to 7.5° fluoroscopic rotation (SMS: 3 cm) and up to 30° of inlet and 15° of outlet (SIS: ± 3.3 cm). SMS distance effectively corresponded to the degree of rotation present (r = 1.00, CI: 0.97 to 1.00, p < 0.0001) and was strongly correlated to TD (r = -0.95, CI: -0.99 to -0.67, p = 0.001). SIS distance effectively corresponded to the degree of tilt present (r = -0.97, CI: -0.99 to -0.88, p < 0.0001) and was correlated to TD (r = 0.94, CI: 0.75 to 0.99, p = 0.0001). Linear regression models determined that, with every degree of rotation and tilt, TD was altered by 0.4 mm and 0.09 mm, respectively (p = 0.0004, r2 = 0.93 and p < 0.0001, r2 = 0.94, respectively). Interobserver reliability among observers was excellent (0.92). CONCLUSION: The TD has excellent interobserver reliability and is minimally impacted by up to 7.5° of rotation, 30° inlet tilt, and 15° of outlet tilt. Utilization of these thresholds may ensure reliability of TD measurements when assessing pelvis stress radiographs.

Quantitative Assessment of Iteratively Denoised 3D SPACE with Inner-Volume Excitation and Simultaneous Multi-Slice BLADE for Optimizing Female Pelvis Magnetic Resonance Imaging at 1.5 T.

RATIONALE AND OBJECTIVES: High-resolution T2-weighted magnetic resonance imaging (MRI) of the pelvis is the main technique used for diagnosing benign and malignant uterine diseases. However, the procedure may be time-consuming and requires training and experience. Therefore, this study was performed to compare the image quality of standard clinical BLADE (stBLADE) with a prototypical accelerated simultaneous multi-slice (SMS) BLADE procedure with either improved temporal resolution (tr) at the same slice thickness (SL) or improved spatial resolution (sr) with the same examination time and a prototypical isotropic 3D SPACE procedure with inner-volume excitation and iterative denoising. MATERIALS AND METHODS: Patients who underwent clinically indicated MRI of the uterus were included in this prospective study and underwent stBLADE (acquisition time, 2 min 59 s; SL, 4 mm) and SMS BLADE (tr) with the same SL (4 mm) but reduced examination time (1 min 20 s) as well as SMS BLADE (sr) with thinner slices (3 mm) and comparable examination time (3 min 16 s). In addition, 3D SPACE was acquired in a sagittal orientation (5 min 36 s). The short axis of the cervix and the long axis of the corpus uteri were reconstructed in 1-mm and 3-mm SLs, retrospectively. Subjective overall image impression, delineation of anatomy/organs, lesion demarcation, and motion artifacts were assessed using a 5-point Likert scale and compared among the different techniques. The preferred sequence was then selected by three independent assessors. RESULTS: The analysis was based on 38 women (mean age, 44 ± 15 years). The overall image impression was similar for stBLADE, SMS BLADE (sr), and SMS BLADE (tr) but was significantly lower for 3D SPACE than stBLADE (p = 0.01). SMS BLADE (sr) was considered the preferred sequence because of slightly better performance in terms of overall image impression, organ delineation, and lesion demarcation, but without statistical significance. Both SMS BLADE (tr) and (sr) produced significantly fewer motion artifacts than stBLADE (p < 0.01 and p = 0.01), with no significant difference between SMS BLADE (tr) and (sr), while 3D SPACE had a significantly lower rating than stBLADE (p < 0.01). Image quality was rated as the least diagnostic criterion in all sequences and all cases. CONCLUSION: SMS BLADE (sr) was the preferred sequence for MRI of the female pelvis, with higher sr than stBLADE. SMS BLADE (tr) may also be used to reduce the acquisition time without compromising image quality. Despite its lower image quality, 3D SPACE can also reduce the examination time and improve the workflow because of the possibility of retrospective multiplanar reconstructions.

Anatomic, computed tomographic, and ultrasonographic assessment of the lymph nodes in presumed healthy adult cats: the abdomen, pelvis, and hindlimb.

BACKGROUND: The computed tomography (CT) and ultrasonography (US) features of lymph nodes of the abdomen, pelvis, and hindlimb in healthy cats are poorly described in the current literature. A prospective anatomic and reference interval study was therefore performed. The lymph nodes of six feline cadavers were identified, and dimensions were measured (length, width, and height). The lymph nodes from 30 healthy adult cats were identified and measured using CT (pre- and postcontrast) and US. The identification and dimensions of the separate lymph nodes were compared between imaging techniques and the anatomic study. RESULTS: The identification of lymph nodes was most frequent in CT, and the dimensions were overall larger than those identified and measured in US and the anatomic study. The caudal epigastric and sacral lymph nodes were not identified in the anatomic study. The ischiatic, lumbar aortic, internal iliac, and caudal epigastric lymph nodes were not visualized in US. The height presented the main statistical differences among techniques. The lymph nodes were mainly homogeneous in pre- and postcontrast CT and US images. Some lymph nodes showed a hyperattenuating periphery with a hypoattenuating center (on pre- and postcontrast images) and a hypo-/isoechoic periphery with a hyperechoic center, representing the hilar fat. The lymph nodes were commonly elongated and rounded except for the jejunal lymph nodes, which had an irregular shape. CONCLUSIONS: The assessment of most of the abdominal, pelvic, and hindlimb lymph nodes in the cat is feasible using CT and US, with CT performing best. Factors like the amount of adipose tissue and contrast administration subjectively improved the lymph node visualization and assessment. The measurements and features reported are proposed as reference values.

Assessment of the acetabular version in relation to sagittal sacropelvic parameters.

The relationship between acetabular orientation and the sacropelvic parameters is of interest to both hip and spine surgeons as it is increasingly clear disease in one area can affect the other, including the outcome of surgical procedures. The aim of this study was to further clarify the relationship between measures of acetabular orientation and sacropelvic parameters. This study utilized a trauma CT database. A total of 100 scans on adult patients without overt hip or spinal disease were included. Measures of acetabular orientation included the acetabular sagittal angle (ASA) which uses the anterior pelvic plane as a reference and sacroacetabular angle which uses the sacral endplate as a reference (SA); spinopelvic parameters include the pelvic incidence (PI), sacral anatomic orientation (SAO) and pelvic thickness (PTH). Mean age 48.2 years (SD 18.0), 62% male. Mean values were: PI 50.5, SAO 50.7, PTH 106.4 mm, ASA-right 62.1, ASA-left 64.0, SA-right 67.2, and SA-left 65.4. There was substantial correlation between PI and SA (r = 0.628-0.630) and also between SAO and SA (-0.657 to -0.692). Liner regression determined SA was best predicted by the model: SA = 81 × SAO + 0.36 × PI. When using the anterior pelvic plane as a reference to define acetabular orientation, there does not appear to be any significant relationship between the sagittal orientation of the acetabulum and sacropelvic parameters. Using the sacrum as a common point of reference allows some further understanding of the interplay between pelvic parameters and the orientation of the acetabulum.

Organ dose from Varian XI and Varian OBI systems are clinically comparable for pelvic CBCT imaging.

Pelvic cone-beam computed tomography (CBCT) occurs daily in many radiotherapy clinics as a part of image-guided verification before treatment. These images are acquired by the use of ionizing radiation. The dose received by CBCT imaging is often not quantified in a patient's radiation therapy prescription. The purpose of this work was to quantify the dose from a TrueBeam XI pelvic CBCT imaging system. The dose to organs from this imaging protocol was then compared with published dose data for OBI v1.4 pelvic CBCT imaging. A model of the Varian XI imager was constructed using GATE Monte Carlo scripting language. The model was calibrated by correlation with experimental measurements. An IBA 3D water tank was used to perform relative dose measurements in water. An adult anthropomorphic Alderson phantom with embedded thermolumeniscent dosimeters was used to evaluate dose from prostate CBCT imaging. Following the calibration, the GATE model was used to simulate the dose from the XI pelvic CBCT protocol to the ICRP computational anthropomorphic phantom. The Monte Carlo model constructed in GATE was validated for use in dose estimates for the XI pelvic imaging protocol. The D50 and D10 values tabulated the pelvic CBCT protocol show that doses to organs in the pelvic region are comparable for both systems. For a clinician who intends to evaluate the dose to organs as a result of CBCT imaging of the pelvis from the TrueBeam XI system, for the purposes of treatment planning, the doses reported for OBI v1.4 given in AAPM TG-180 provide a valid estimate.

An Innovative Technique for Intraoperative Radiological Assessment of Pelvic and Spine Fractures in Austere Environment.

INTRODUCTION: Managing pelvic and spine fractures in the austere environment can be challenging even for skilled orthopedic surgeons, largely due to the difficulty of radiological visualization of bone structures. We present a simple alternative to the metallic operating table by placing the patient on a spinal board that will allow for a better radiological assessment of these fractures. MATERIAL AND METHODS: A cross-sectional, descriptive, and retrospective study was carried out in the period between 2015 and 2020. The study population was all patients with pelvic o spine fractures, managed surgically using a spinal board in the Spanish Role 2 or in the Spanish Role 4. RESULTS: Seven patients underwent surgery in total using a spinal board, pelvic fracture being the the main diagnosis (n = 6; 85.71%). The distribution of surgical procedures was as follows: percutaneous pedicle screw fixation (one case), external fixation of the pelvis (two cases), percutaneous screw fixation of the pelvis (two cases), and open reduction and internal fixation of the pelvis (two cases). The mean duration of surgical interventions was 52 minutes, and a successful reduction and synthesis of the fracture was obtained in all the patients, with no complications reported. CONCLUSION: A spinal board can be a useful, simple, and effective device for the orthopedic surgeon in the deployed setting. The described technique is simple, fast, and efficient in getting a complete radiological assessment of complex regions such as the pelvis and the spine, facilitating the surgical management of these injuries.

Assessment of sagittal spinopelvic alignment in asymptomatic Chinese juveniles and adolescents: a large cohort study and comparative meta-analysis.

STUDY DESIGN: Retrospective study and comparative meta-analysis. OBJECTIVE: To document the sagittal spinopelvic alignment in a large cohort study in asymptomatic Chinese juveniles and adolescents, and to explore whether these parameters were different from various regions using meta-analysis. METHODS: Medical records of 656 asymptomatic Chinese juveniles and adolescents were reviewed, whose mean age was 13.14 ± 3.41 years old, including 254 male and 402 female volunteers. Demographic and lateral radiological parameters were evaluated. Furthermore, a systematic online search was performed to identify eligible studies. Weight mean difference (WMD) with 95% confidence interval (CI) were used to evaluate whether these sagittal parameters were different from various regions. RESULTS: The mean value of sagittal spinopelvic alignment in this study was calculated and analyzed respectively. Significant differences of PI (34.20 ± 4.00 vs. 43.18 ± 7.12, P < 0.001) and PT (3.99 ± 6.04 vs. 8.42 ± 7.08, P < 0.001) were found between juveniles and adolescents. A total of 17 studies were recruited for meta-analysis. For juvenile populations, TK, PI and SS of Caucasians were significantly larger than those of our study (all P < 0.001). As for adolescent populations, PI (P = 0.017), TK (P = 0.017) and SS (P < 0.001) of Caucasians was found to be greater when compared with that of our study. All in all, TK, PI and SS in Chinese pre-adult populations were significantly smaller than those populations in Caucasian regions (all P < 0.001). CONCLUSION: Our study was the first large-scale study that reported the mean values of sagittal parameters in asymptomatic Chinese juveniles and adolescents. There were significant differences in TK, PI and SS between our study and other previous reported populations, which reminded us for using specific mean values in different populations when restoring a relatively normal sagittal spinopelvic balance in spinal deformity.

PATIENT-SPECIFIC ORGAN DOSE EVALUATION BASED ON MONTE CARLO SIMULATION AND DOSE METRICS IN PAEDIATRIC CHEST-ABDOMEN-PELVIS CT EXAMINATIONS.

This study aimed to determine organ doses based on Monte Carlo (MC) simulations for individual paediatric patients undergoing chest-abdomen-pelvis computed tomography (CT) examinations and to evaluate correlations of organ doses with dose metrics. MC simulations were performed by inputting detailed descriptions of a CT scanner, scanning parameters and CT images of 51 paediatric patients aged from 0 to 10 years into the simulation software. Organ doses for six radiosensitive organs were determined from dose distribution images obtained as the simulation results. The correlations of organ doses with dose metrics such as volume CT dose index, size-specific dose estimates (SSDEs), and organ-specific SSDEs were evaluated from the corresponding coefficients of determination. Organ doses for ages of 0-1 and 1-5 years were 22%-32% lower than those for ages of 5-10 years. Organ doses exhibited higher linear correlations with SSDEs and organ-specific SSDEs, and can be easily estimated using the linear regression.

Radiological assessment of persistent retroperitoneal and lateral pelvic lymph nodes after neoadjuvant therapy for rectal cancer: An analysis of the United States Rectal Cancer Consortium.

INTRODUCTION: Management of retroperitoneal and lateral pelvic lymph nodes (RLPN) in rectal cancer remains unclear. With total neoadjuvant therapy (TNT), more patients have radiologic complete clinical response (rCR). We sought to evaluate the impact of radiographic persistent RLPN after neoadjuvant therapy on survival. MATERIALS AND METHODS: Patients with rectal adenocarcinoma with isolated RLPN metastasis, who received neoadjuvant therapy before surgery were included from the United States Rectal Cancer Consortium database. Primary outcomes were recurrence-free survival (RFS) and overall survival (OS). RESULTS: Of 77 patients, all received neoadjuvant therapy, with 35 (46%) receiving TNT. Posttreatment, 33 (43%) had rCR while 44 (57%) had radiographic persistent RLPN. Median number of radiographic positive RLPN was 1 (IQR 1-2). Receipt of TNT was associated with radiographic RLPN rCR (OR 4.77, 95% CI 1.81-12.60, p < .01). However, there was no difference in RFS and OS between patients who achieved rCR or with persistent RLPN (all p > .05). CONCLUSIONS: Radiographic persistence of RLPN was not associated with worse survival in well-selected patients and may not be a reliable indicator of pathological response. TNT may be the preferred management strategy to select patients given its association with rCR. Radiographic persistence of RLPN after preoperative therapy should not necessarily preclude surgery.