Bone Density by Specific Anatomic Location Using Hounsfield Samples of the Lower Extremity: A Multi-center Retrospective Analysis

Understanding bone mineral density and its effects on patient outcomes is a useful tool for lower extremity surgeons. Historically, dual-energy X-ray absorptiometry scans have been the gold standard for quantifying bone mineral density. In this study, we look at an indirect way to measure bone mineral density using Hounsfield units on computed tomography. The aim of this study is to establish normal physiological Hounsfield ranges in specific bones of the foot by analyzing Hounsfield unit measurements and determining associated factors. We hypothesize that there will be a difference in density based on age, sex, and anatomic location. Patient data from January 2010 to January 2020 were retrospectively analyzed from 2 institutions. Nine anatomic locations (calcaneus, talar body, talar head, navicular, cuboid, medial cuneiform, head of first and fifth metatarsal, and base of first proximal phalanx) were measured for bone mineral density averages. In total, 137 patients were evaluated (71 males, 66 females) with an average age of 54 years. Significant differences in density were found between the 9 anatomic locations. Age was confirmed to be a significant covariate with inverse relation to Hounsfield units, p < .001. There were no density differences between sexes at any of the locations, except the talar head, p < .001. This is the first study to our knowledge to establish normal physiological ranges of bone density on computed tomography for specific anatomic locations of the foot. This quantitative approach to bone density and the established effect of age, sex, and location is pivotal for diagnostic and preoperative planning.

Routine chest CT combined with the osteoporosis self-assessment tool for Asians (OSTA): a screening tool for patients with osteoporosis

INTRODUCTION

The osteoporosis self-assessment tool for Asians (OSTA) is a common screening tool for osteoporosis. The seventh thoracic CT (CT-T7) Hounsfield unit (HU) measured by chest CT correlates with osteoporosis. This study aimed to investigate the diagnostic value of OSTA alone, CT-T7 alone, or the combination of OSTA and CT-T7 in osteoporosis.

MATERIALS AND METHODS

In this study, 1268 participants were grouped into 586 men and 682 women. We established multiple linear regression models by combining CT-T7 and OSTA. Receiver operating characteristic (ROC) curves were used to evaluate the ability to diagnose osteoporosis.

RESULTS

In the male group, the mean age was 59.02 years, and 108 patients (18.4%) had osteoporosis. In the female group, the mean age was 63.23 years, and 308 patients (45.2%) had osteoporosis. By ROC curve comparison, the CT-T7 (male, AUC = 0.789, 95% CI 0.745-0.832; female, AUC = 0.835, 95% CI 0.805-0.864) in the diagnosis of osteoporosis was greater than the OSTA (male, AUC = 0.673, 95% CI 0.620-0.726; female, AUC = 0.775, 95% CI 0.741-0.810) in both the male and female groups (p < 0.001). When OSTA was combined with CT, the equation of multiple linear regression (MLR) was obtained as follows: female = 3.020-0.028*OSTA-0.004*CT-T7. In the female group, it was found that the AUC of MLR (AUC = 0.853, 95% CI 0.825-0.880) in the diagnosis of osteoporosis was larger than that of CT-T7 (p < 0.01). When the MLR was 2.65, the sensitivity and specificity were 53.9% and 90%, respectively.

CONCLUSION

For a patient who has completed chest CT, CT-T7 (HU) combined with OSTA is recommended to identify the high-risk population of osteoporosis, and it has a higher diagnostic value than OSTA alone or CT-T7 alone, especially among females. For a female with MLR greater than 2.65, further DXA examination is needed.

Psoas weakness following oblique lateral interbody fusion surgery: a prospective observational study with an isokinetic dynamometer

BACKGROUND CONTEXT

Although the surgical corridor used for oblique lateral interbody fusion (OLIF) protects the intrapsoas nerves by causing minimal compression, transient weakness remains the most commonly reported postoperative complication.

PURPOSE

Using a dynamometer to evaluate how the hip flexor strength changes following OLIF.

STUDY DESIGN/SETTING

A prospective observational study.

PATIENT SAMPLE

Forty-six patients who underwent single or multi-level OLIF for lumbar spondylolisthesis.

OUTCOME MEASURES

Isokinetic dynamometer values (peak torque, total work, average power), visual analogue scale (VAS) scores for leg pain, hypoesthesia, subjective weakness of the left hip flexor muscle, Oswestry disability index, body mass index, bone mineral density, radiologic findings of the psoas muscle (cross-sectional area, Hounsfield unit (HU), fat portion grade), and psoas retraction time.

METHODS

The isokinetic muscle strength of the hip flexor was measured five times (preoperatively and postoperatively at 2 days, 1 week, 1 month, and 3 months) for both legs. The peak torque was defined as the postoperative strength of the left hip flexor muscles, and was compared to the preoperative baseline value. The strength of the left and right hip flexor muscles were also compared at each time point. For logistic regression analysis, when the peak torque was below the median value, it was defined as lower peak torque.

RESULTS

Up to 1 week after surgery, the strength of the left hip flexor muscle decreased significantly (paired difference in peak torque was 22.6%, p<.001). In the results of multivariate logistic regression analysis, diabetes (odds ratio [OR]=8.43, p=.020) and the HU of the psoas muscle (OR=0.916, p=.034) were associated with lower peak torque 1 week after surgery. From 1 month after surgery, postoperative weakness of the psoas muscle was not significant. In the questionnaire survey, subjective left hip flexion weakness was reported in 8.5% (4/47) of patients 1 week after surgery, and it remained in only 2.1% (1/47) of patients after 3 months of operation. The frequency of left anterior thigh pain and hypoesthesia decreased from 85.1% (40/47) at 1 week to 2.1% (1/47) at 3 months after surgery. The mean VAS score for left anterior thigh or groin pain decreased significantly at 1 month after surgery (PO2D: 4.04±1.84, PO1M: 1.67±1.10, p<.001).

CONCLUSIONS

Dynamometer measurement showed that psoas strength declined significantly up to 1 week after OLIF surgery. Patients with diabetes or lower HU of the psoas muscle showed delayed recovery from postoperative weakness of the psoas muscle. However, the weakness was insignificant from 1 month after surgery. At 3 months after surgery, the other psoas-related problems (left anterior thigh pain and hypoesthesia) also disappeared.

Association Between Hounsfield Units in Preoperative Wrist Computed Tomography Scans and Outcomes After Wrist Fracture Surgery

Purpose

This work aims to evaluate the hypothesis that the value of Hounsfield units (HU), as a marker of bone density, in preoperative wrist computed tomography (CT) scans correlates with the functional outcomes as measured by patient reported outcomes (PROs) after distal radius fracture surgery with volar locking plate fixation.

Methods

Of a database of 92 wrist fractures operated on in our hospital between 2011 and 2020, with a preoperative CT scan performed, we selected the cases with a minimum follow-up period of 12 months. After applying the exclusion criteria, the final cohort comprised 64 patients. Three measurements of HU were performed in correlative coronal sections of the capitate bone. PROs were determined using two functional questionnaires (DASH and PRWE) and one quality of life questionnaire (SF-12). The statistical relationship between PROs and the HU measurements obtained via a CT scan was analyzed.

Results

Patients were classified into two groups, osteoporotic (OST) or non-osteoporotic (non-OST), according to the optimal cut-off value of 323 HU selected using a ROC curve. The median DASH questionnaire score in the OST group was significantly higher (1.7 vs 10.0, p = 0.003).

Conclusion

HU values in preoperative wrist CT scans may help to identify osteoporotic bone in patients prior to wrist fracture surgery and lead to an improved surgical indication and treatment strategy.

Level of Evidence

Level of evidence: Prognostic III.

Prediction of osteoporosis and osteopenia by routine computed tomography of the lumbar spine in different regions of interest

Background

We aimed to investigate the utility of Hounsfield units (HU) obtained from different regions of interest in opportunistic lumbar computed tomography (CT) to predict osteoporosis coupling with data of dual-energy X-ray absorptiometry (DXA).

Methods

A total of 100 patients who attended a university hospital in Shanghai, China, and had undergone CT and DXA tests of the lumbar spine within 3 months were included in this retrospective review. Images were reviewed on axial sections, and regions of interest (ROI) markers were placed on the round, oval, anterior, left, and right of the L1–L4 vertebra to measure the HU. The mean values of CT HU were then compared to the bone mineral density (BMD) measured by DXA. Receiver operator characteristic curves were generated to determine the threshold for diagnosis and its sensitivity and specificity values.

Results

The differences in CT HU of different ROI based on DXA definitions of osteoporosis, osteopenia, and normal individuals were statistically significant (p < 0.01). The HU values of the different ROI correlated well with the BMD values (Spearman coefficient all > 0.75, p < 0.01). The threshold for diagnosing osteoporosis varies from 87 to 111 HU in different ROIs, and the threshold for excluding osteoporosis or osteopenia is 99–125 HU.

Conclusion

This is the first study on osteoporosis diagnosis of different ROI with routine CT lumbar scans. There is a strong correlation between CT HU of different ROI in the lumbar spine and BMD, and HU measurements can be used to predict osteoporosis.

Hounsfield unit measurement method and related factors that most appropriately reflect bone mineral density on cervical spine computed tomography

OBJECTIVE

Our study's purpose was to determine the most reliable Hounsfield unit (HU) measurement method to reflect bone mineral density (BMD) on cervical spine computed tomography (CT) and to identify any factors that influence these results.

MATERIALS AND METHODS

We retrospectively analyzed 439 consecutive patients with mild head and neck injuries. Mean HU values of the C2-C7 vertebra were determined on each sagittal, coronal, and axial CT image. Correlation patterns were analyzed between the HU value and corresponding dual-energy X-ray absorptiometry (DXA) in the lumbar vertebra (T-score) and femoral neck (T-score). A sub-group analysis was performed according to patient age, sex, and degree of spinal degeneration.

RESULTS

The correlation coefficients for HU and DXA ranged from 0.52 to 0.65 in all cervical segments. A simple linear regression analysis revealed the following formula: T-score = 0.01 × (HU) - 4.55. The mean HU values for osteopenia and osteoporosis were 284.0 ± 63.3 and 231.5 ± 52.8, respectively. The ROC curve indicated that the HU method has a sensitivity of 89.2% and specificity of 88.7% to diagnose osteoporosis. The HU measurement showed a high correlation value (range: r = 0.64-0.70) with spine DXA score regardless of the degree of degeneration or patient age or sex.

CONCLUSION

HU values using the upper two cervical vertebrae (C2 and C3) reflected a more reliable BMD level than other segments. Additionally, the HU of cervical CT provided reliable information regardless of measurement plane, age or sex, and degree of degeneration.

Significance of Measuring Lumbar Spine 3-Dimensional Computed Tomography Hounsfield Units to Predict Screw Loosening

BACKGROUND

Osteoporosis is a well-known risk factor of screw loosening. Classically, dual-energy x-ray absorptiometry (DEXA) scan is an easy and cost-effective method of detecting bone mineral density (BMD). However, T-score on DEXA scan can be overestimated in patients with degenerative changes of the spine. Our objective was to identify correlation between Hounsfield unit (HU) measured by 3-dimensional computed tomography (3D-CT) and screw loosening.

METHODS

A total of 113 patients treated with lumbosacral spinal fusion were reviewed and categorized into a screw loosening group and a normal group to compare their average values of preoperative CT HU. Screw loosening was defined as radiolucent area around screw that was thicker than 1 mm with a "double halo sign".

RESULTS

There were statistically significant differences in patient age and steroid use between screw loosening and non-loosening groups. There was no significant difference in BMD or T-score between the 2 groups. However, HU values measured in axial, coronal, and sagittal images were significantly different between the 2 groups. In the receiver operating characteristic for HU values measured in CT images, the greatest area under the curve was 0.774 and that was in case of Hounsfield unit measured by axial CT images from L1 to L4.

CONCLUSIONS

Preoperative CT HU is associated with screw loosening. It can be a better predictor of screw loosening than DEXA scan. The best predictor of screw loosening in this study is the average value of HU from L1 to L4 in axial cut.

Hounsfield units: A promising non-invasive tool for diagnosing benign prostatic hyperplasia

OBJECTIVE

The clinical symptoms in benign prostatic hyperplasia (BPH) are directly proportional to prostate volume. We aimed to show whom and when to intervene in a noninvasive way, correlating the patient's subjective symptoms with objective diagnostic tools.

MATERIAL AND METHOD

International Prostate Symptom Score (IPSS) was evaluated in patients who consulted the urology outpatient clinic for the first time with lower urinary tract symptoms (LUTS). Subsequently, PSA, urea, creatinine, complete urinalysis, uroflowmetry, urinary tract ultrasound and non-contrast lower abdominal computed tomography (CT) examinations were requested. Prostate central (transitional zone) zone and peripheral zone HU scores, prostatic urethral length and bladder wall Hounsfield units (HU) scores were recorded by using computed tomography (CT). The ellipsoid formula was used for ultrasonographic and tomographic measurements of prostate size (anteroposterior diameter × transverse diameter × longitudinal diameter × 0.52).

RESULTS

A statistically significant negative correlation was found between the prostate peripheral zone/central zone HU ratio and the maximum flow rate measured in the uroflowmetry test.

CONCLUSION

This is the first study in the literature to evaluate the correlation between voiding parameters such as Qmax, Qave and IPSS scores, and prostate and bladder wall HU scores obtained by computed tomography examination in BPH patients. A significant relationship has been detected between the peripheral zone/central zone HU ratio and Q max. Additional studies with larger patient populations could better clarify the contribution of HU in the diagnosis of BPH and treatment decision making of these patients.

Dual-Energy CT-Based Bone Mineral Density Has Practical Value for Osteoporosis Screening around the Knee

Introduction: Adequate bone quality is essential for long term biologic fixation of cementless total knee arthroplasty (TKA). Recently, vertebral bone quality evaluation using dual-energy computed tomography (DECT) has been introduced. However, the DECT bone mineral density (BMD) in peripheral skeleton has not been correlated with Hounsfield units (HU) or central dual-energy X-ray absorptiometry (DXA), and the accuracy remains unclear. Materials and methods: Medical records of 117 patients who underwent TKA were reviewed. DXA was completed within three months before surgery. DECT was performed with third-generation dual source CT in dual-energy mode. Correlations between DXA, DECT BMD and HU for central and periarticular regions were analyzed. Receiver operating characteristic (ROC) curves were plotted and area under the curve (AUC), optimal threshold, and sensitivity and specificity of each region of interest (ROI) were calculated. Results: Central DXA BMD was correlated with DECT BMD and HU in ROIs both centrally and around the knee (all p < 0.01). The diagnostic accuracy of DECT BMD was higher than that of DECT HU and was also higher when the T-score for second lumbar vertebra (L2), rather than for the femur neck, was used as the reference standard (all AUC values: L2 > femur neck; DECT BMD > DECT HU, respectively). Using the DXA T-score at L2 as the reference standard, the optimal DECT BMD cut-off values for osteoporosis were 89.2 mg/cm3 in the distal femur and 78.3 mg/cm3 in the proximal tibia. Conclusion: Opportunistic volumetric BMD assessment using DECT is accurate and relatively simple, and does not require extra equipment. DECT BMD and HU are useful for osteoporosis screening before cementless TKA.

High-stress distribution in the lateral region of the subtalar joint in the patient with chronic lateral ankle instability

PURPOSE

Chronic lateral ankle instability (CLAI) is associated with osteoarthritis (OA). However, the characteristics of patients with CLAI who progress to OA are not clear. Measurement of Hounsfield Unit (HU) value on computed tomography (CT) is reported to be useful to evaluate the stress distribution. We aimed to evaluate the stress distribution in the ankle and subtalar joints and factors enhancing it in patients with CLAI.

MATERIALS AND METHODS

Thirty-three ankles with CLAI (CLAI group) and 26 ankles without CLAI (control group) were included. A mean age of CLAI was 35.2 years and control was 30.3 years. Color map was created in the ankle and subtalar joint according to the HU values using three-dimensional CT to identify the region with high HU values, and HU values in those regions were measured using two-dimensional CT and compared between control and CLAI groups. In CLAI group, the relationships between HU values and ankle activity score (AAS), OA, talar tilting angle (TTA), cartilage injury were assessed.

RESULTS

The HU values in the anteromedial region of the talus and lateral region in the subtalar joint were higher than those in the control. In CLAI, patients with an AAS of ≧ 6, over 10° of TTA, cartilage injury, and OA changes in the medial gutter had significantly higher HU values in the lateral region of the subtalar joint than those with an AAS of ≦5, less than 10° of TTA without cartilage injury and OA change.

CONCLUSIONS

CLAI patients, especially in the patients with high activity level, large TTA, cartilage injury, and OA changes at the medial gutter, have high HU values in the lateral region of the subtalar joint, which suggests that disruption of the subtalar compensation toward OA will occur. For these patients, instability should be completely eliminated to prevent ankle OA.

LEVEL OF EVIDENCE

Level III, comparative series.

Evaluation of femoral head bone quality by Hounsfield units: a comparison with dual-energy X-ray absorptiometry

BACKGROUND

Osteoporosis is associated with decreases in bone mineral density (BMD) and is diagnosed using dual-energy X-ray absorptiometry (DXA). Computed tomography (CT), performed in routine practice, can also be used to evaluate bone quality without additional cost.

PURPOSE

To determine whether Hounsfield units (HU), a standardized CT attenuation coefficient, measured from the femoral head correlated with DXA-measured BMD.

MATERIAL AND METHODS

We evaluated 82 patients (14 men, 68 women; mean age, 67 years) undergoing femoral DXA and CT (non-enhanced abdominopelvic and hip scans) with 130 kV to determine whether HU correlated with T-scores. HU were measured by two radiologists using the largest spherical region of interest including the medullary bone of the femoral head from the junction point of the most caudal section of the femoral head with the femoral neck in 5-mm axial sections. The correlations of both sides' HU values with their ages and DXA femur T-score were evaluated.

RESULTS

HU values obtained from both femoral heads showed significant variation between the osteoporotic and non-osteoporotic groups (both P = 0.000) and strongly correlated with each other and DXA femur T-scores (left r = 0.75, right r = 0.73, respectively). In ROC curve analysis, predictive power of left HU values in identifying patients with osteoporotic femur DXA T-score was 0.905, and for right HU values it was 0.924. Osteoporosis cutoff values were 198 HU and 204 HU for the left and right hips, respectively.

CONCLUSIONS

HU obtained from CT performed in routine practice correlated with the DXA scores, thus providing an alternative method to determine regional bone quality without additional cost. This may be useful when choosing a fixation method, especially in trauma cases with already-performed abdominopelvic or pelvic CT in emergency services.

Predicting Nonunions in Ankle Fractures Using Quantitative Tibial Hounsfield Samples From Preoperative Computed Tomography: A Multicenter Matched Case Control Study

The aim of this study is to use tibial Hounsfield unit measurements from preoperative computed tomography scans of ankle fractures to predict delayed union and nonunion. We hypothesize that patients with lower Hounsfield unit averages, an indirect measure of lower bone mineral density, in the distal tibia are more likely to develop delayed union and nonunion complications after ankle fracture surgery. Patient data from January 2010 to January 2020 were retrospectively analyzed from 2 institutions. Exposure cases of delayed union or nonunion that had preoperative computed tomography were compared to 5 controls matched for sex, age, and classification. 3 measurements were taken from the tibia on axial computed tomography and averaged to create a summative measure for overall bone health. Statistical analysis was used to analyze the relationship between the groups. 19 exposure patients were compared to 95 control patients. There were 16 females and 3 males in the exposure group aged from 30 to 88 years. Average follow-up was 1.6 years. The average exposure and control Hounsfield measurements were 186 (161-210) and 258 (248-269), respectively. Significant differences were found for all measured averages. This is the first study to our knowledge relating preoperative tibial Hounsfield measurements to healing rates of ankle fractures. Measurements taken from any of the 3 sites or the average could be an indicator of overall bone health. Using this technique on preoperative imaging will help surgeons adjust their perioperative planning for patients at higher risk for delayed union and nonunion.

The diagnostic utility of unenhanced computed tomography of the brain and D-dimer levels in acute cerebral venous sinus thrombosis: A quantitative study

Objectives

(1) To calculate the sensitivity and specificity of the Hounsfield Unit (HU), the HU to hematocrit (H:H) ratio, and the D-dimer level in the diagnosis of acute CVST. (2) To assess the D-dimer level's linear relationship with the HU and the H:H ratio.

Materials and Methods

A single-center retrospective case-control study was conducted from 2005 to 2020. The inclusion criteria for the thrombosed and control groups were specified. A region of interest (ROI) was plotted on the respective sinuses to calculate the HU. The H:H ratio was calculated by dividing the HU value by the hematocrit value. The receiver operating characteristic curve was used to calculate the sensitivity and specificity of the HU and the H:H ratio at different cutoff values. The Pearson correlation was used to assess the linear relationship between the D-dimer level and the HU and H:H ratio.

Results

There were 19 patients in the thrombosed group and 28 patients in the control group. There were significant differences in the mean HU (71 ± 6.3 vs. 45 ± 4.8, P < 0.001) and the mean H:H ratio (2.11 ± 0.38 vs. 1.46 ± 0.63,P < 0.001). An optimal HU value of 56 yielded 100% sensitivity and specificity. An H:H value of 1.48 yielded a sensitivity of 100% and a specificity of 65%, an H:H ratio of 1.77 demonstrated a sensitivity of 85% and a specificity of 90%, and an H:H ratio of 1.88 yielded a sensitivity of 79% and a specificity of 93%. D-dimer levels had a 95% and 71% sensitivity and specificity, respectively. There was a significant moderately positive linear correlation between the D-dimer level and the HU (r = 0.52, P < 0.001) and the H:H ratio (r = 0.61, P < 0.001).

Conclusion

Unenhanced CT of the brain can be a valuable objective diagnostic tool for acute CVST diagnosis. Hounsfield blood density and its normalized ratio with hematocrit are positively correlated with D-dimer levels, which may indicate active blood coagulation in a cerebral venous sinus.

Distribution of hounsfield unit values in the pelvic bones: a comparison between young men and women with traumatic fractures and older men and women with fragility fractures: a retrospective cohort study

Background

The fixation strength of bone screws depends on bone mineral density (BMD), so it is important to evaluate bone strength at fracture sites. Few studies have investigated BMD in the pelvis. The aims of this study were to measure the regional Hounsfield unit (HU) values in the cancellous bone of the acetabulum and pelvic ring and to compare these values between young and older patients.

Methods

This study enrolled young patients with high-energy trauma (aged 20–44 years; young group) and older patients with low-energy trauma (aged 65–89 years; older group). Patients without pelvic computed tomography (CT) scans, those with pelvic bone implants, and those who died were excluded. The HU values on the contralateral (non-fractured) side of the pelvis were measured on CT scans. The CT data were divided into 7 areas: the pubic bone, the anterior and posterior walls and roof of the acetabulum, the ischial tuberosity, the body of the ilium, and the third lumbar vertebra. The HU values in each area were compared between the young and older groups.

Results

Sixty-one young patients and 154 older patients were included in the study. The highest HU value was in the roof of the acetabulum regardless of age and sex. HU values were significantly higher in the ischial tuberosity and body of the ilium and lower in the pubic bone and anterior wall. The HU values in all pelvic areas were significantly lower in the older group than in the young group, especially in the anterior area.

Conclusions

HU values in the 6 pelvic areas were not uniform and were strongly related to load distribution. The HU distribution and age-related differences could explain the characteristic causes and patterns of acetabular fractures in the older and may help in surgical treatment.

The Effect of COVID 19 on Liver Parenchyma Detected and measured by CT scan Hounsfield Units

BACKGROUND

COVID 19 may affect organs other than lungs, including liver, leading to parenchymal changes. These changes are best assessed by unenhanced computed tomography (CT). We aim to investigate the effect of COVID 19 on liver parenchyma by measuring the attenuation in CT scan Hounsfield unit (HU).

MATERIALS AND METHODS

A cohort of patients, who tested COVID 19 polymerase chain reaction positive, were enrolled and divided into two groups: fatty liver (FL) group (HU ≤ 40) and nonfatty liver (NFL) group (HU > 40) according to liver parenchyma attenuation measurements by high resolution noncontrast CT scan. The CT scan was performed on admission and on follow up (10-14 days later). Liver enzyme tests were submitted on admission and follow up.

RESULTS

Three hundred and two patients were enrolled. Liver HU increased significantly from 48.9 on admission to 53.4 on follow up CT scan (P<0.001) in all patients. This increase was more significant in the FL group (increased from 31.9 to 42.9 [P =0.018]) Liver enzymes were abnormal in 22.6% of the full cohort. However, there was no significant change in liver enzymes between the admission and follow up in both groups.

CONCLUSION

The use of unenhanced CT scan for assessment of liver parenchymal represents an objective and noninvasive method. The significant changes in parenchymal HU are not always accompanied by significant changes in liver enzymes. Increased HU values caused by COVID 19 may be due to either a decrease in the fat or an increase in the fibrosis in the liver.

Predicting ESWL success by determination of Hounsfield unit on non-contrast CT is clinically irrelevant in children

The necessity of determining stone density by non-contrast computerized tomography (NCCT) before extracorporeal shock wave lithotripsy (ESWL) is a controversial topic due to the radiation exposure. We aimed to investigate whether stone density is helpful in predicting the success of ESWL in pediatric patients or not. In this retrospective study, database of a single center was used to identify 232 children aged between 2 and 16 years. Patients with abnormal renal anatomy, distal obstruction, a known cystine stone disease, a previous history of an intervention regarding stone, and an insufficient follow-up period (< 3 months) were excluded from the study. A total of 209 patients were included in the study (94 with NCCT, 115 without NCCT). Groups were compared in terms of stone size, stone location, and stone-free rate at 3 months after a single ESWL session. The mean age was 6.17 ± 3.27 years and 120 (57.4%) of the patients were male and 89 (42.6%) were female. Mean stone size was 11.7 mm in NCCT group and 12.3 mm in non-NCCT group (p 0.128). The complete stone clearance rate in NCCT and non-NCCT group at 3 months after ESWL was 57.4% (54/94) and 54.7% (63/115), respectively, and there was no statistically significant difference (p 0.316). In conclusion, unnecessary NCCT use should be avoided before ESWL considering the similar success rates after ESWL and the risk of exposure to radiation.

Can gray values be converted to Hounsfield units? A systematic review

OBJECTIVES

The purpose of this systematic review was to answer the focus question: "Could the gray values (GVs) from CBCT (cone beam computed tomography) be converted to Hounsfield units (HUs) in multidetector computed tomography (MDCT)?"

METHODS

The included studies try to answer the research question according to the PICO strategy. Studies were gathered by searching several electronic databases and partial grey literature up to January 2021 without language or time restrictions. The methodological assessment of the studies was performed using The Oral Health Assessment Tool (OHAT) for in vitro studies and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) for in vivo studies. The Grading of Recommendations Assessment, Development and Evaluation (GRADE system) instrument was applied to assess the level of evidence across the studies.

RESULTS

2710 articles were obtained in Phase 1, and 623 citations remained after removing duplicates. Only three studies were included in this review using a two-phase selection process and after applying the eligibility criteria. All studies were methodologically acceptable, although in general terms with low risks of bias. There are some included studies with quite low and limited evidence estimations and recommendation forces; evidencing the need for clinical studies with diagnostic capacity to support its use.

CONCLUSIONS

This systematic review demonstrated that the GVs from CBCT cannot be converted to HUs due to the lack of clinical studies with diagnostic capacity to support its use. However, it is evidenced that three conversion steps (equipment calibration, prediction equation models, and a standard formula (converting GVs to HUs)) are needed to obtain pseudo Hounsfield values instead of only obtaining them from a regression or directly from the software.

Hounsfield Unit for Assessing Bone Mineral Density Distribution Within Cervical Vertebrae and Its Correlation With the Intervertebral Disc Degeneration

STUDY DESIGN

Retrospective radiological analysis.

OBJECTIVE

To assess bone mineral mass distribution within cervical vertebrae based on Hounsfield unit (HU) measurement, and explore its correlation with intervertebral disc degeneration.

METHOD

Three hundred and twenty-four patients with degenerative cervical spine disease were retrospectively reviewed and divided into six groups according to age. HU measurement of the whole vertebrae from C3 through C7 was obtained, then HU measurement within upper and lower part of the vertebrae on sagittal plane were obtained from C3 through C7. Disc degeneration on MRI was graded from I to V using the Pfirrmann classification.

RESULTS

There was a significant difference in the HU value from C3 to C7 among Group II to Group VI, the HU value presented consistently decreasing trend from young patients to old patients. In C6 and C7 vertebrae, there were significant differences in HU values between upper and lower parts of the vertebrae. More importantly. In all groups, HU values were highest in the upper part of the C4 vertebrae and then gradually decreased towards C3 and C7. HU value of both upper and lower vertebrae presented decreasing trend along with the aggravation of the disc degeneration.

CONCLUSION

HU values are not typically consistent throughout all levels of the cervical spine and the distribution within the vertebrae is not homogeneous. Decreased vertebral BMD and vertebral osteoporosis may trigger or exacerbate the adjacent intervertebral disc degeneration.

Correlation between Hounsfield unit derived from head, thorax, abdomen, spine and pelvis CT and t-scores from DXA

OBJECTIVES

CT examination can potentially be utilised for early detection of bone density changes with no additional procedure and radiation dose. We hypothesise that the Hounsfield unit (HU) measured from CT images is correlated to the t-scores derived from dual energy X-ray absorptiometry (DXA) in multiple anatomic regions.

MATERIALS & METHODS

Data were obtained retrospectively from all patients who underwent both CT examinations - brain (frontal bone), thorax (T7), abdomen (L3), spine (T7 & L3) or pelvis (left hip) - and DXA between 2014 and 2018 in our centre. To ensure comparability, the period between CT and DXA studies must not exceed one year. Correlations between HU values and t-scores were calculated using Pearson's correlation. Receiver operating characteristic (ROC) curves were generated, and the area under the curve (AUC) was used to determine threshold HU values for predicting osteoporosis.

RESULTS

The inclusion criteria were met by 1043 CT examinations (136 head, 537 thorax, 159 lumbar and 151 left hip). The left hip consistently provided the most robust correlations (r = 0.664-0.708, p < 0.001) and the best AUC (0.875-0.893). Meanwhile, thorax T7 and lumbar L3 showed average correlations (range of r values is 0.497-0.679, p < 0.001, AUC range = 0.680-0.783, 95% CI 0.561-0.922, all p < 0.02) and moderate AUC (0.680-0.783). Frontal bone shows low correlation and weak AUC with r < 0.5, AUC = 0.538-0.655, all p > 0.05.

CONCLUSION

HU values derived from the hip, T7 and L3 provided a good to moderate correlation to t-scores with a good prediction for osteoporosis. The suggested optimal thresholds may be used in clinical settings after external validations are performed.

Evaluation of celiac disease with uniphasic and multiphasic dynamic MDCT imaging

PURPOSE

An analysis of dynamic contrast MRI has been shown to provide valuable information about disease activity in Crohn's disease and Celiac disease (CD). However, there are no reports of dynamic multi-detector computer tomography use in patients with CD. The aim of this study is to determine and compare the perfusion dynamics of the patients treated with control subjects and the perfusion dynamics in patients with untreated CD, using dynamic contrast in MDCT and compare studying contrast dynamics in Marsh types as well.

METHODS

In this retrospective study, uniphasic and multiphasic MDCT, untreated, treated, incompatible CD patients and healthy control group duodenum wall thickness and HU values were compared in terms of patient groups and modified Marsh types.

RESULT

In dynamic CT, the highest contrast curve was observed in the untreated group and Marsh type 1. While the contrast curve of the untreated and non-compliant patients increased rapidly and showed wash out, the type 4 contrast curve was observed, whereas the treated and control group slowly increased type 5 contrast curve. In the contrast-enhanced CT in the venous phase, in the ROC analysis between Marsh 1-2 and Marsh 3a-c, the sensitivity was 97% and the specificity was 87% when the cut off was taken as 4.45 mm for wall thickness (p: 0.005).

CONCLUSION

Contrast-enhanced single-phase and dynamic MDCT imaging in CD patients may be useful in evaluating the inflammatory and pathological process in the small intestine.

Clinical features and literature review related to the material differences in thread rhinoplasty: Two case reports

BACKGROUND

Thread rhinoplasty can trigger a reaction to thread material, which is a foreign body. We compared clinical features induced by absorbable and non-absorbable threads following thread rhinoplasty.

CASE SUMMARY

Two patients who underwent different thread materials showed different clinical courses and different Hounsfield unit (HU) values in computed tomography. Patients with absorbable thread showed high HU values similar to a metallic material, and the HU value of inflammation was similar to vascular tissues with a lot of water (250). In the intraoperative field, absorbable thread materials and micro-abscesses were observed. In contrast, in the case of a non-absorbable thread, an object presumed to be thread was seen on the computed tomography (CT), and the HU value of inflammatory tissues was less than 100. In both patients, post-operative HU decreased to less than 100 and the clinical course improved. In both cases, histopathologic findings revealed foreign body granuloma associated with inflammation.

CONCLUSION

Absorbable threads were more aggressive and are more easily detected on CT.

Objective Evaluation of Cerebral Venous Sinus Attenuation on Plain CT Brain and Detecting Anemia. Noticing the "Unnoticed"

Context

Plain computed tomography (CT) of the brain is an important first-line investigation of choice in an acute neurologic setup. Unless clinically suspected concealed areas like the confluence of venous sinuses often go unnoticed. Diagnosing anemia, thrombosis, or polycythemia correlating the CT attenuation values might prove to be fruitful in early patient management where the mode of varied clinical presentations causes a clinical dilemma.

Aims

1) To determine the objective correlation between CT attenuation of the cerebral venous sinus and hemoglobin (Hb) as well as hematocrit (HCT) value and 2) to detect anemia from measuring venous sinus attenuation.

Methods and Materials

An exploratory study design of 200 patients, who had plain CT of the head and Hb and HCT levels obtained within 24 h of the scan.

Statistical Analysis Used

Two-tailed unpaired t-test was used to test the difference between two independent samples. Correlation and regression analyses were used to assess the correlation between two quantitative variables.

Results

A significant correlation was observed between the Hb-Hounsfield unit (HU) and HCT-HU. The simple linear regression model revealed that HU (P value < 0.001) was significantly correlated with Hb and the regression model was, Hb = 2.1 + 0.2 × HU. Similarly, HU (P value < 0.001) was significantly correlated with HCT and regression model was HCT = 6.2 + 0.7 × HU.

Conclusions

Objective attenuation values of dural sinuses on plain CT can be positively correlated with Hb and HCT values. Considering the cutoff of 35.5 HU, we were able to show the specificity of 100% for the detection of anemia.

Value of Hounsfield Units in the Evaluation of Isolated Sphenoid Sinus Lesions

Radiologic findings of fungal sinus disease are generally opacification in paranasal computed tomography (CT) images. The Hounsfield unit (HU) is a standardized objective unit that is also suitable for measuring remodeling and opacifications on CT scans of bone sections of patients with chronic rhinosinusitis. We hypothesized that HU values could provide valuable information in isolated sphenoid sinus lesions before surgery. Between 2012 and 2019, 35 patients underwent functional endoscopic sinus surgery for sphenoid sinus lesions. Tissues obtained from the sphenoid sinus were divided into two groups, fungal and nonfungal, according to the findings of histopathologic examinations. HU values were measured in sphenoid sinus sections on paranasal CT scans of these two groups. Differences in mean and maximum HU values between the two groups were statistically significant (p < .05). The maximum HU values calculated from the sphenoid sinus were 435.08 and 196.23 (p ≤ .05) in the fungal group and nonfungal group, respectively. The mean HU values calculated from the sphenoid sinus were 64.31 and 29 (p ≤ .05) in the fungal and nonfungal groups, respectively. At the maximum cutoff value of 241, the sensitivity and specificity of the HU maximum were 84.6% and 77.3%, respectively. At the mean cutoff value of 41.5, the sensitivity and specificity of the HU mean were 76.9% and 86.4%, respectively. HU is an objective value used in radiographic density measurement. The HU values were higher in fungal lesions than in nonfungal inflammations, and they are useful in preoperative measurement.

Diagnostic Value of Hounsfield Unit and Hematocrit Levels in Cerebral Vein Thrombosis in the Emergency Department

BACKGROUND

Unenhanced computed tomography (CT) is a frequently used imaging method in patients who are evaluated in the emergency department with suspected cerebral vein thrombosis (CVT).

OBJECTIVES

The aim of this study was to investigate the usefulness of the Hounsfield unit (HU) value determined by CT and its ratio to the patient's hematocrit (Htc) value in the diagnosis of cerebral vein thrombosis.

METHODS

This retrospective study evaluated 41 patients with acute cerebral venous sinus thrombosis and 41 age- and sex-matched control participants. Two experienced observers independently evaluated the CT scan and measured the attenuation of the dural sinuses.

RESULTS

There was no significant difference in age, gender, hemoglobin, and Htc values between the two groups. The mean HU value was 75 ± 7 HU in the CVT group and 52 ± 6 HU in the control group (p < 0.001). The mean HU/Htc ratio was 1.9 ± 0.3 in the CVT group and 1.3 ± 0.1 in the control group (p < 0.001). The optimal threshold value for HU was determined as 66, and sensitivity at this value was 93%, and specificity was 98%. The optimal threshold value for HU/Htc was determined as 1.64, and the sensitivity at this value was 90% and the specificity was 100%.

CONCLUSION

Hyperattenuation in the dural sinuses and the HU/Htc ratio in unenhanced brain CT scans have high diagnostic value in detecting CVT.

Effect of osteoporotic conditions on the development of peritumoral brain edema after LINAC-based radiation treatment in patients with intracranial meningioma

PURPOSE

Disruption of the tumor-brain barrier in meningioma is a crucial factor in peritumoral brain edema (PTBE). We previously reported the possible effect of osteoporosis on the integrity of the arachnoid trabeculae because both the bone and the arachnoid trabeculae are composed of type 1 collagen. We hypothesized that osteoporotic conditions may be associated with PTBE occurrence after radiation treatment in patients with meningioma.

METHODS

A receiver operating characteristic curve analysis was used to identify the optimal cut-off values of mean skull Hounsfield unit for predicting osteopenia and osteoporosis in patients from our registry. Multivariate Cox regression analysis was used to determine whether possible osteoporosis independently predicted PTBE development in patients with meningioma after radiation.

RESULTS

A total of 106 intracranial meningiomas were included for the study. All patients received linear accelerator-based radiation therapy in our hospital over an approximate 6-year period. Multivariate Cox regression analysis identified that hypothetical osteoporosis was an independent predictive factor for the development of PTBE in patients with meningioma after linear accelerator-based radiation treatment (hazard ratio 5.20; 95% confidence interval 1.11-24.46; p = 0.037).

CONCLUSIONS

Our study suggests that possible osteoporotic conditions may affect PTBE development after linear accelerator-based radiation treatment for intracranial meningioma. However, due to the study's small number of patients, these findings need to be validated in future studies with larger cohorts, before firm recommendations can be made.