Diagnostic effectiveness of deep learning-based MRI in predicting multiple sclerosis: A meta-analysis.

OBJECTIVES: The brain and spinal cord, constituting the central nervous system (CNS), could be impacted by an inflammatory disease known as multiple sclerosis (MS). The convolutional neural networks (CNN), a machine learning method, can detect lesions early by learning patterns on brain magnetic resonance image (MRI). We performed this study to investigate the diagnostic performance of CNN based MRI in the identification, classification, and segmentation of MS lesions. METHODS: PubMed, Web of Science, Embase, the Cochrane Library, CINAHL, and Google Scholar were used to retrieve papers reporting the use of CNN based MRI in MS diagnosis. The accuracy, the specificity, the sensitivity, and the Dice Similarity Coefficient (DSC) were evaluated in this study. RESULTS: In total, 2174 studies were identified and only 15 articles met the inclusion criteria. The 2D-3D CNN presented a high accuracy (98.81, 95% CI: 98.50-99.13), sensitivity (98.76, 95% CI: 98.42-99.10), and specificity (98.67, 95% CI: 98.22-99.12) in the identification of MS lesions. Regarding classification, the overall accuracy rate was significantly high (91.38, 95% CI: 83.23-99.54). A DSC rate of 63.78 (95% CI: 58.29-69.27) showed that 2D-3D CNN-based MRI performed highly in the segmentation of MS lesions. Sensitivity analysis showed that the results are consistent, indicating that this study is robust. CONCLUSION: This metanalysis revealed that 2D-3D CNN based MRI is an automated system that has high diagnostic performance and can promptly and effectively predict the disease.

Complication Rates and Risk of Recurrence After Percutaneous Radiofrequency Ablation and Microwave Ablation for the Treatment of Liver Tumors: a Meta-analysis.

RATIONALE AND OBJECTIVES: The rate of complications and risk of local recurrence following percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) for liver tumors varies significantly between investigations. This meta-analysis aimed to assess complication rates and risk of local recurrence after percutaneous RFA and MWA. MATERIALS AND METHODS: PubMed, Medline, Web of Science, the Cochrane Library, Embase, Google Scholar, and CINAHL were systematically searched from database inception until August 2022 to retrieve articles reporting the complication rates and risk of recurrence after percutaneous RFA and MWA for the treatment of liver tumors. Pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated and displayed by forest plots. To measure heterogeneity, Cochran Q and I2 statistics were also applied. Egger's test and funnel plots were also performed to assess any potential publication bias. Additionally, subgroup analysis was done to investigate the source of heterogeneity. RESULTS: 26 studies including 2026 and 1974 patients for RFA and MWA, respectively, were included. The rate of minor complications was significantly higher after MWA compared to RFA, yielding an overall OR of 0.688 (95% CI: 0.549-0.862, P = 0.001). Similarly, the rate of major complications was significantly higher after MWA than RFA (P = 0.012), yielding an overall OR of 0.639 (95% CI: 0.450-0.907). No significant difference was found between RFA and MWA in terms of local recurrence after ablation (P > 0.05). In addition, there was no statistical evidence of publication bias. CONCLUSION: When most factors are considered equally, percutaneous RFA and MWA can be considered safe modalities for the treatment of liver tumors, with RFA superior in terms of the incidence of minor and major complications.

Impact of long duty hours on education and well-being of diagnostic radiology residents: A national survey in Saudi Arabia.

Objectives: The primary purpose of this study was to assess and report the perceived negative impact of long duty hours on education and personal well-being among medical trainees in the diagnostic radiology residency training program in Saudi Arabia. Methods: This cross-sectional study used a questionnaire (sent by email) with eight indicators related to the education and well-being of radiology residents in Saudi Arabia during the academic year 2019-2020. Participants were given a five-point Likert response format for each indicator. The relative importance index (RII) was calculated to rank the different indicators. Results: Our of 337 residents, 116 diagnostic radiology trainees completed the survey, with a response rate of 34.4%. A total of 102 (87.9%) indicated their preference for 16-hour shifts instead of the currently implemented 24-hour duty system. Using the RII, three items related to the post-duty day ranked at the top of the list. The negative impact on sleep rhythm during the post-call day ranked first (mean 4.23 ± 1.02, RII 0.84), followed by the impact on social life, family activities, and exercise during the post-call day (mean 4.09 ± 1.06, RII 0.81). The third highest ranking factor was missing academic activities on the post-call day (mean 3.91 ± 1.15, RII 0.78). There was no relationship between negative perception and gender (P > 0.05). Conclusion: The 24-hour duty system had a negative impact on radiology residents' education and personal well-being, especially for items related to the post-call day. Reforming duty hours should be considered to promote residents' well-being.

The Diagnostic Deceiver: Radiological Pictorial Review of Tuberculosis.

Tuberculosis (TB) is a bacterial infection with Mycobacterium tuberculosis; it is a public health problem worldwide and one of the leading causes of mortality. Since December 2019, the COVID-19 pandemic has created unprecedented health challenges and disrupted the TB health services, especially in high-burden countries with ever-increasing prevalence. Extrapulmonary and even pulmonary TB are an important cause of nonspecific clinical and radiological manifestations and can masquerade as any benign or malignant medical case, thus causing disastrous conditions and diagnostic dilemmas. Clinical manifestations and routine laboratory tests have limitations in directing physicians to diagnose TB. Medical-imaging examinations play an essential role in detecting tissue abnormalities and early suspecting diagnosis of TB in different organs. Radiologists and physicians should be familiar with and aware of the radiological manifestations of TB to contribute to the early suspicion and diagnosis of TB. The purpose of this article is to illustrate the common radiologic patterns of pulmonary and extrapulmonary TB. This article will be beneficial for radiologists, medical students, chest physicians, and infectious-disease doctors who are interested in the diagnosis of TB.

Diagnostic features of tuberous sclerosis complex: case report and literature review.

Tuberous sclerosis complex (TSC) is a rare autosomal dominant genetic syndrome that is caused by mutations in the tumour suppressor genes TSC1 or TSC2 which causes multiorgan growths. TSC presents at any age as a wide range of clinical and phenotypic manifestations with varying severity. The main goal of this article was to state two cases of TSC and review the most commonly reported major and minor diagnostic clinical features and the most common features that led to an investigation of possible TSC diagnosis. Herein, we report two cases of TSC, which both presented with seizures during the first 6 months of life. Case 1 presented with multiple types of seizures from 6 months of age and was diagnosed by multiple calcified subependymal nodules (SENs) detected by computed tomography and magnetic resonance imaging (MRI). Case 2 presented with seizures from 3 months of age and was diagnosed prenatally when a tumour was seen in her heart during antenatal ultrasonography. In conclusion, the literature review revealed that neurological manifestations (mainly seizures) were the main feature that led to investigation and diagnosis of TSC followed by abdominal manifestations (mainly renal features) and antenatal follow-up imaging. Other manifestations in skin, chest, eyes, teeth and heart rarely led to TSC diagnosis. In some cases, TSC was incidentally discovered by medical imaging. The cortical tubers, SENs, and subependymal giant cell astrocytomas brain lesions were the most commonly reported major features. Skin features including angiofibromas, ungual fibromas and shagreen patch were the second most common major features reported in the literature. However, skin manifestations were not a common led to investigation and diagnosis of TSC. Renal features, mainly angiomyolipomas (AMLs), were the third most common major feature reported. Medical imaging plays an essential role in diagnosis of TSC, and clinical features are important clues that lead to investigation for the disease.

Extensive abdominal lymphangiomatosis involving the small bowel mesentery: A case report.

BACKGROUND: Abdominal lymphangiomatosis is a rare benign condition accounting for less than 1% of all the cases of lymphangiomatosis. Management usually involves radical surgical excision; however, depending upon the extent of involvement, patient condition, and absence of complications, conservative management can be also considered. CASE SUMMARY: We present the case of a 32-year-old male who presented with short onset abdominal pain and melena. Physical examination findings were within normal limits, except for left lower abdominal tenderness. Upper gastrointestinal endoscopy was within normal limits. Abdominal and pelvic ultrasound and computed tomography (CT) scan revealed numerous, variably-sized cystic lesions within the abdominal cavity, exclusively and extensively affecting the small bowel mesentery with sparing of the retroperitoneum. The diagnosis was confirmed by CT and cytological examination. Radical surgical excision was technically impossible in this patient because of the extensive involvement of the mesentery; therefore, the patient was managed conservatively. CONCLUSION: Extensive and exclusive small bowel mesentery involvement in abdominal lymphangiomatosis is rare. Imaging modalities play an important role in establishing the diagnosis and conservative management can be considered when surgery is technically impossible.

An unusual and atypical presentation of the novel coronavirus: A case report and brief review of the literature.

The coronavirus disease 2019 (COVID-19) is a highly contagious novel infection that predominantly presents with fever and respiratory symptoms. However, COVID-19 can masquerade as an acute coronary syndrome, leg pain or swelling with venous thrombosis, loss of consciousness with cerebral venous thrombosis, confusion, limb weakness with brain infarction, facial neuralgia, acute conjunctivitis, acute appendicitis, and testicular pain. We report on a 42-year-old man who presented with mild symptoms of COVID-19. The patient's electrocardiogram showed an ST-segment elevation myocardial infarction (STEMI) due to a left coronary thrombosis. The patient was managed conservatively with medicines and had an uneventful recovery. Emergency physicians should have a high index of suspicion for the unusual presentations of COVID-19.

Impact of COVID-19 Pandemic on Training and Well-Being in Radiology Residency: A National Survey of Diagnostic Radiology Trainees in Saudi Arabia.

OBJECTIVES: To understand and report the perceived impact of the COVID-19 pandemic on radiology residents in Saudi Arabia with respect to their education, clinical activities, and personal well-being. METHODS: The survey questionnaire was designed by a team of experts based on a review of the literature and was distributed electronically through the Saudi Commission for Health Specialties to residents registered in all radiology residency training programs in Saudi Arabia during the academic year 2019 to 2020. Categorical variables were presented as counts and percentage. Numerical variables were presented as mean and standard deviation if normally distributed. Chi-square testing was used to compare categorical variables with the perceived impact of the COVID-19 pandemic. Spearman correlation was used to correlate numerical variables at the level of significance p-value < 0.05. RESULTS: A total of 109 residents completed the online survey during the study period, with a response rate of 32.2% (109/337). The mean age was 27.3 years (standard deviation, 1.86). The majority of respondents (71.5%, 78/109) reported either a severe or moderate negative impact on educational activities. Also, the majority (73.4%, 80/109) reported either a minimal or moderate negative impact on clinical activities. Residents training in the western province perceived a statistically higher negative impact on educational activities compared to their peers in other regions (p = 0.01). Residents in their second year of residency training perceived a statistically higher negative impact on their participation in clinical activities (p = 0.014). Less than half of the respondents (45.9%, 50/109) reported that they were redeployed to work in another department. The majority (80%, 40/50) reported a negative impact on their well-being. CONCLUSION: The majority of radiology residents in Saudi Arabia reported a negative impact of the COVID-19 pandemic on their education, clinical activities, and personal well-being. Our study also identified and explored some of the innovative solutions and strategies implemented by the training programs and the SCFHS to mitigate the negative effects on trainees.

Identification of posterior visual pathway lesions and MRI burden in people with Multiple Sclerosis.

OBJECTIVES: This review systematically identifies posterior visual pathway lesions and MRI burden in people with multiple sclerosis (MS). METHODS: The articles were searched through Web of Science, Medline, and Embase databases on January 2020, for English language articles from 2000 to 2019. RESULTS: This review presents summary measures if related to MRI assessment to an overall measure of MS and visual pathway lesions. A total of 44 articles fulfilled all inclusion criteria, covering the period 2000-2019. Different atypical outcomes reveal a low risk for subsequent clinically predefined MS development, specifically in the presence of normal brain MRI. Several impairments related to quality of life have been identified as a result of the effect of retinal nerve fiber layer, ganglion cell layer, and inner plexiform layer. CONCLUSION: The afferent visual system in MS offers unique accessibility and structure-related functions with further understanding offered by electrophysiology, considering vision as a useful framework for examining new multiple sclerosis therapies.

Diffuse astrocytoma and the diagnostic dilemma of an unusual phenotype: A case report.

Diffuse astrocytoma is an infiltrating type of glioma (World Health Organization grade II), which even with histopathology, is difficult to diagnose. Magnetic resonance imaging (MRI) is the cornerstone for diagnoses and follow-up of brain gliomas. This report describes a case of diffuse astrocytoma in a 48-year-old man who presented with sudden right-sided weakness and repeated convulsive attacks. On brain computed tomography, the case was diagnosed and treated as an acute infarction. Ten days later, the patient returned with a total loss of consciousness. Brain MRI images revealed an irregularly outlined lesion involving the splenium of the corpus callosum that extended into the left periventricular parietal lobe of the brain with cystic foci in the septum pellucidum. Contrast-enhanced and new sequences of MRI was helpful in approach to diagnosis because of its superior tissue characterization. The histopathology results ultimately confirmed the diagnosis of diffuse astrocytoma. The patient died postoperatively.

Primary infertility secondary to a hidden posterior urethral valve representing a diagnostic challenge in the fifth decade.

Posterior urethral valves (PUVs) are frequently recognized during the perinatal period. Delayed diagnosis is reported usually within the first decade of life with diverse clinical presentations. In the current case report, we describe a 45 years old man patient who presented with aspermia and primary infertility for 8 years in whom his diagnostic workup revealed radiological imaging suggestive of PUVs. This phenomenon was confirmed by cystourethroscopy that showed obstructive valve. Endoscopic ablation resulted in significant improvement of his seminal parameter with successful conception.

Cardiac hydatid cyst in the right ventricle: An unusual case at a rare site.

Hydatid disease is a parasitic infection by the larval stage of the tapeworm Echinococcus granulosus. It affects liver, lungs and rarely other organs. Medical imaging provide the basis for diagnosis. This case report describes an extremely rare location of cardiac hydatid cyst in the right ventricle of the heart. We describe a 23-year-old woman who presented with shortness of breath and productive cough. Laboratory investigations showed marked eosinophilia and anemia. Chest radiography and abdominal ultrasonography were unremarkable. Cardiac computed tomography (CT) identified two well-defined fluid densities in the right ventricle without contrast enhancement. A transthoracic echocardiography (TTE) showed two cystic lesions in the right ventricular cavity that was attached to the interventricular septum. Hydatid cyst was the most likely diagnosis followed by the possibility of a congenital cardiac cyst. An open-heart surgery with cardiac cystectomy was performed. Post-operative analysis of the resected specimens showed multiple hydatid cysts with living scolices of Echinococcus granulosus. The patient recovered uneventfully and was discharged on oral albendazole.

Superior sagittal sinus thrombosis after spinal anesthesia.

Superior sagittal sinus thrombosis is an uncommon phenomenon that could occur in patients with a risk for thrombosis. It has been reported after spinal anesthesia with persistent cerebrospinal fluid leak. The current case is a young 29-year-old man who was complaining of persistent headache after spinal anesthesia for varicocelectomy and a new onset of blurred vision with a sign of papilledema. The diagnosis was confirmed with magnetic resonance imaging and proved to be superior sagittal sinus thrombosis. He was started on anticoagulant therapy and showed gradual improvement. No previous case has been reported in the literature in a patient without prothrombotic status risk.

Descriptive study of knee lesions using magnetic resonance imaging and correlation between medical imaging diagnosis and suspected clinical diagnosis.

OBJECTIVE: This study aimed to assess the meniscus and cruciate ligament lesions of the knee using magnetic resonance imaging (MRI) and to investigate the correlation between clinical and MRI diagnoses. PATIENTS AND METHODS: Herein, we reviewed the electronic medical records of 240 patients who underwent knee MRI. The images were evaluated and then the clinical and MRI diagnoses were compared. RESULTS: Of the 240 patients, 66% were male and the mean age was 40.6 ± 15.5 years (range, 2-79 years). Knee pain alone was the most common presenting symptom (50.64%) followed by pain after trauma (47.92%). Majority of the knee lesions were medial meniscus (MM) lesions (63%) followed by osteoarthritis (48%) and ACL lesions (35%). The majority of the MM and ACL lesions were tears (54.6% and 69.41%, respectively) followed by degeneration (33.55% and 17.65%, respectively). However, the MM lesions were predominantly observed in the posterior horn (Odds ratio [OR], 152; 95% confidence interval (CI), 21.550-1072.113; P < 0.001). The ACL lesions were significantly more common in men than in women (OR, 0.355; 95% CI, 0.191-0.661; P = 0.001), and altered signal intensity on T2- and proton density-weighted images was the most common sign (P < 0.001). A strong compatibility was observed between the clinical and MRI diagnoses (Kappa = 0.141; P < 0.001). CONCLUSION: MM and ACL lesions are the most common injuries of the knee, which can be diagnosed by physical examination in most cases. Further confirmation by MRI should be reserved for doubtful cases only.

The Role of Phosphodiesterase Inhibitors in the Management of Cavernositis With Multifocal Abscesses: A Report of Case Series.

INTRODUCTION: Cavernositis is a rare acute infection of the corporal bodies of the penis. It might result in corporal cavernosal abscesses, fibrosis, and subsequently erectile dysfunction if the treatment is inadequate. Previous reports advocate penile aspiration when cavernosal abscesses were significantly present. AIM: We report 2 cases of cavernositis treated by the standard antimicrobial therapy in addition to the daily use of phosphodiesterase type 5 inhibitors (iPDE-5). METHODS: We include 2 patients who fulfill the criteria for the diagnosis of cavernositis. They were diagnosed clinically based on history and physical examination. Patient 1 had multifocal abscesses on initial penile contrast-enhanced magnetic resonance imaging (MRI). This patient showed rapid clinical improvement with the addition of phosphodiesterase inhibitor (PDEi) to the antimicrobial therapy without the need for surgical drainage of the abscesses. Patient 2 had persistent infection despite 3 weeks of oral second-generation cephalosporin (Cefuroxime). But he showed significant clinical improvement after being started on PDEi in conjunction with the current antimicrobial therapy. Follow-up after 3 months by clinical examination and penile magnetic resonance imaging in both patients showed normal erectile function with no scarring. CONCLUSION: PDEi have promising results on disease progression and outcomes. It synergizes the effect of antimicrobial therapy and can potentially reduce the residual corporal fibrosis and erectile dysfunction. However, large studies are required to validate and generalize this treatment approach. Bakhsh A, Daqqaq T, Alhasan A, et al. The Role of Phosphodiesterase Inhibitors in the Management of Cavernositis With Multifocal Abscesses: A Report of Case Series. Sex Med 2020;8:318-322.

Predictive value of ultrasound imaging in differentiating benign from malignant breast lesions taking biopsy results as the standard.

BACKGROUND: Breast lesions (BLs) are abnormal swellings within the breast. The importance lies in need to exclude breast cancer. OBJECTIVE: Due to the role of ultrasound (US) imaging in evaluating of BLs, this study was conducted to evaluate the predictive value of US imaging for differentiating benign from malignant BLs and to assess the need of biopsy in BLs. METHOD: A retrospective review of diagnostic results of 134 patients with BLs. All patients underwent breast US imaging and US-guided biopsy for cytology or histopathology. The results of both were compared. RESULTS: Out of 134 patients were included in this study, the mean age was 38.45 ± 15.82 years (range, 18-90 years), and all patients were female. BLs were benign in 99 cases (73.9%) and malignant in 35 cases (26.1%). Among 98 patients with BLs diagnosed benign with US, 96.9% were confirmed benign with biopsy results and only 3.1% were malignant. The overall sensitivity of US imaging for discriminating of benign BLs was 95.95%, with a specificity of 91.42%, and positive predictive value of 96.94%. The results revealed strong compatibility between diagnoses by US imaging and biopsy results (P < 0.001), the measure of agreement kappa = 0.866, and the Spearman's correlation coefficient = 0.866. CONCLUSION: US imaging is a highly valuable imaging method in differentiating benign from malignant BLs. It usually predicts the benign nature of BLs with excellent diagnostic accuracy. US-guided fine-needle aspiration and core-needle biopsies are not necessary in most cases of BLs.

Influence of fractional anisotropy thresholds on diffusion tensor imaging tractography of the periprostatic neurovascular bundle and selected pelvic tissues: do visualized tracts really represent nerves?

Background Diffusion tensor imaging (DTI) tractography has recently been shown to successfully visualize periprostatic tracts allegedly representing the neurovascular bundle. Purpose To examine the impact of different fractional anisotropy (FA) thresholds on the results of DTI tractography in the male pelvis as well as to evaluate the resulting specificity for nerve tracts. Material and Methods Ten healthy male volunteers were examined at 3 Tesla. DTI tractography was performed based on seed points placed circularly around the prostate, in the rectoprostatic angle, the peripheral zone of the prostate, the sciatic nerve, and in addition the urinary bladder using FA thresholds of 0.20, 0.05, and 0.01. DTI tract number and DTI tract length measured with different FA thresholds were compared. ANOVA with repeated measures was used for statistics. Results DTI tract number and tract length were significantly dependent on FA thresholds. While a FA threshold of 0.20 visualized the typical distribution of DTI tracts in the sciatic nerve, a FA threshold of ≤0.05 was necessary to yield results visually mimicking the distribution of nerve tracts in the NVB. However, with such low FA thresholds even in the filled urinary bladder DTI tracts could be visualized. With FA thresholds of 0.20, the number and length of periprostatic DTI tracts did not differ from those measured within the prostate. Conclusion DTI tractography can be used to visualize DTI tracts periprostatically. However, one may doubt that these DTI tracts represent nerve tracts and that the periprostatic neurovascular bundle can be evaluated in a meaningful way with the current methods available.

T2- and diffusion-weighted magnetic resonance imaging at 3T for the detection of prostate cancer with and without endorectal coil: An intraindividual comparison of image quality and diagnostic performance.

OBJECTIVES: To intraindividually compare image quality and diagnostic performance of multiparametric MRI (mpMRI) at 3T for the detection of prostate cancer (PCa) using a pelvic phased-array coil (PAC) and a combined endorectal and pelvic phased-array coil (ERC-PAC). METHODS: Forty-five patients were prospectively included and received mpMRI of the prostate using a PAC and an ERC-PAC during one imaging session. Two radiologists evaluated image quality and the most suspicious lesion according to the PI-RADS scoring system. Results of MRI-TRUS-fusion biopsy of the prostate served as reference standard. Patient comfort and acceptance were assessed using a standardized questionnaire. RESULTS: Overall image quality for T2WI was rated significantly better with an ERC-PAC compared to a PAC (p=0.0038). The weighted kappa for PI-RADS scores for T2WI and DWI with a PAC and an ERC-PAC was 0.70 and 0.73, respectively. For a PI-RADS sum score including T2WI and DWI the area under the curve with a PAC and an ERC-PAC were 0.95-0.99 and 0.93-0.97, respectively (p=0.1395). CONCLUSION: For T2WI and DWI performed at 3T index PCa lesion identification and evaluation did not differ significantly with both coil setups. Patients preferred MRI without an ERC. Therefore, the use of an ERC may be omitted in a prostate cancer detection setting.

Individual selection of X-ray tube settings in computed tomography coronary angiography: Reliability of an automated software algorithm to maintain constant image quality.

OBJECTIVES: To evaluate a software tool that claims to maintain a constant contrast-to-noise ratio (CNR) in high-pitch dual-source computed tomography coronary angiography (CTCA) by automatically selecting both X-ray tube voltage and current. METHODS: A total of 302 patients (171 males; age 61±12years; body weight 82±17kg, body mass index 27.3±4.6kg/cm(2)) underwent CTCA with a topogram-based, automatic selection of both tube voltage and current using dedicated software with quality reference values of 100kV and 250mAs/rotation (i.e., standard values for an average adult weighing 75kg) and an injected iodine load of 222mg/kg. RESULTS: The average radiation dose was estimated to be 1.02±0.64mSv. All data sets had adequate contrast enhancement. Average CNR in the aortic root, left ventricle, and left and right coronary artery was 15.7±4.5, 8.3±2.9, 16.1±4.3 and 15.3±3.9 respectively. Individual CNR values were independent of patients' body size and radiation dose. However, individual CNR values may vary considerably between subjects as reflected by interquartile ranges of 12.6-18.6, 6.2-9.9, 12.8-18.9 and 12.5-17.9 respectively. Moreover, average CNR values were significantly lower in males than females (15.1±4.1 vs. 16.6±11.7 and 7.9±2.7 vs. 8.9±3.0, 15.5±3.9 vs. 16.9±4.6 and 14.7±3.6 vs. 16.0±4.1 respectively). CONCLUSION: A topogram-based automatic selection of X-ray tube settings in CTCA provides diagnostic image quality independent of patients' body size. Nevertheless, considerable variation of individual CNR values between patients and significant differences of CNR values between males and females occur which questions the reliability of this approach.