Combining Diffusion Tensor Metrics and DSC Perfusion Imaging: Can It Improve the Diagnostic Accuracy in Differentiating Tumefactive Demyelination from High-Grade Glioma?

BACKGROUND AND PURPOSE:Tumefactive demyelinating lesions with atypical features can mimic high-grade gliomas on conventional imaging sequences. The aim of this study was to assess the role of conventional imaging, DTI metrics (p:q tensor decomposition), and DSC perfusion in differentiating tumefactive demyelinating lesions and high-grade gliomas.MATERIALS AND METHODS:Fourteen patients with tumefactive demyelinating lesions and 21 patients with high-grade gliomas underwent brain MR imaging with conventional, DTI, and DSC perfusion imaging. Imaging sequences were assessed for differentiation of the lesions. DTI metrics in the enhancing areas and perilesional hyperintensity were obtained by ROI analysis, and the relative CBV values in enhancing areas were calculated on DSC perfusion imaging.RESULTS:Conventional imaging sequences had a sensitivity of 80.9% and specificity of 57.1% in differentiating high-grade gliomas (P = .049) from tumefactive demyelinating lesions. DTI metrics (p:q tensor decomposition) and DSC perfusion demonstrated a statistically significant difference in the mean values of ADC, the isotropic component of the diffusion tensor, the anisotropic component of the diffusion tensor, the total magnitude of the diffusion tensor, and rCBV among enhancing portions in tumefactive demyelinating lesions and high-grade gliomas (P ≤ .02), with the highest specificity for ADC, the anisotropic component of the diffusion tensor, and relative CBV (92.9%). Mean fractional anisotropy values showed no significant statistical difference between tumefactive demyelinating lesions and high-grade gliomas. The combination of DTI and DSC parameters improved the diagnostic accuracy (area under the curve = 0.901). Addition of a heterogeneous enhancement pattern to DTI and DSC parameters improved it further (area under the curve = 0.966). The sensitivity increased from 71.4% to 85.7% after the addition of the enhancement pattern.CONCLUSIONS:DTI and DSC perfusion add profoundly to conventional imaging in differentiating tumefactive demyelinating lesions and high-grade gliomas. The combination of DTI metrics and DSC perfusion markedly improved diagnostic accuracy.

Tumefactive demyelinating lesions (TDLs) are demyelinating lesions of >2 cm and can mimic high-grade gliomas (HGGs) on conventional MR imaging.¹ Classic conventional and advanced imaging findings may not be present in all cases.^2–4 Because TDLs can be mistaken for gliomas on histopathology, demonstration of the intact axonal process and myelin breakdown products within macrophages is confirmative of demyelination.^5–7 This diagnostic dilemma might lead to a biopsy, an inadvertent operation, and even radiation therapy, which eventually can exacerbate demyelination.Diffusion tensor imaging is a noninvasive method for analyzing the architectural integrity and orientation of axons in white matter. The eigenvalues can be used to calculate various scalar measures of DTI metrics such as ADC, fractional anisotropy (FA), the isotropic component of the diffusion tensor (p), the anisotropic component of the diffusion tensor (q), and the total magnitude of the diffusion tensor (L).^8–10 The most commonly used DTI parameters include ADC (ie, the magnitude of diffusion independent of tissue orientation) and FA (ie, anisotropic diffusion against the total magnitude of diffusion). Less often used measures include total magnitude of diffusion tensor (L) and its isotropic (p) and anisotropic (q) components.The use of FA as a sole measure of anisotropic diffusion can be fallacious because it varies with changes in the anisotropic component and the total magnitude of diffusion.^9,10 The utility of DTI parameters (ie, FA, p, q, and L) has been evaluated in the differentiation of various brain tumors.^11–13 Toh et al¹⁴ evaluated the role of FA in differentiating TDL from HGG by using DTI. However, to the best of our knowledge, there are no studies available evaluating the role of p, qd , and L in differentiating TDL and HGG.Dynamic-susceptibility contrast perfusion imaging allows evaluation of relative cerebral blood volume (rCBV), a marker of neoangiogenesis, and aids in the differentiation of low- and high-grade gliomas.^15,16 TDLs usually have decreased rCBV values due to the absence of neovascular proliferation, which allows differentiation of TDL from HGG.¹⁷ However, TDL can also present with elevated rCBV values and mimic HGG on DSC perfusion, making differentiation difficult.⁴The purpose of this study was to evaluate the efficacy of conventional imaging, diffusion tensor metrics (ADC, FA, p, q, and L), and DSC perfusion (rCBV) in differentiating TDL and HGG. We also assessed the effect of combining imaging parameters—DTI and DSC perfusion imaging—on diagnostic accuracy.     

Can We Perform CT of the Appendix with Less Than 1 mSv? A De-escalating Dose-simulation Study

Objectives

To systematically explore the lowest reasonably achievable radiation dose for appendiceal CT using an iterative reconstruction (IR) in young adults.

Methods

We prospectively included 30 patients who underwent 2.0-mSv CT for suspected appendicitis. From the helical projection data, 1.5-, 1.0- and 0.5-mSv CTs were generated using a low-dose simulation tool and the knowledge-based IR. We performed step-wise non-inferiority tests sequentially comparing 2.0-mSv CT with each of 1.5-, 1.0- and 0.5-mSv CT, with a predetermined non-inferiority margin of 0.06. The primary end point was the pooled area under the receiver-operating-characteristic curve (AUC) for three abdominal and three non-abdominal radiologists.

Results

For the abdominal radiologists, the non-inferiorities of 1.5-, 1.0- and 0.5-mSv CT to 2.0-mSv CT were sequentially accepted [pooled AUC difference: 2.0 vs. 0.5 mSv, 0.017 (95% CI: -0.016, 0.050)]. For the non-abdominal radiologists, the non-inferiorities of 1.5- and 1.0-mSv CT were accepted; however, the non-inferiority of 0.5-mSv CT could not be proved [pooled AUC difference: 2.0 vs. 1.0 mSv, -0.017 (-0.070, 0.035) and 2.0 vs. 0.5 mSv, 0.045 (-0.071, 0.161)].

Conclusion

The 1.0-mSv appendiceal CT was non-inferior to 2.0-mSv CT in terms of diagnostic performance for both abdominal and non-abdominal radiologists; 0.5-mSv appendiceal CT was non-inferior only for abdominal radiologists.

Key points

? For both abdominal and non-abdominal radiologists, 1.0-mSv appendiceal CT could be feasible. ? The 0.5-mSv CT was non-inferior to 2.0-mSv CT only for expert abdominal radiologists. ? Reader experience is an important factor affecting diagnostic impairment by low-dose CT.

     

Does Intraprocedural CT Improve the Success Rate of Adrenal Venous Sampling? A Systematic Review and Meta-Analysis of Data from 809 Patients

CardioVascular and Interventional Radiology - To perform a systematic review and meta-analysis to quantify the technical success rate of adrenal venous sampling (AVS) with and without...     

Can hip impingement be mistaken for tendon pain in the groin? A long-term follow-up of tenotomy for groin pain in athletes

Purpose

There are several reports on the association between pubalgia and intra-articular hip disorders. The purpose of this study was to evaluate the long-term outcome in athletes who underwent tenotomy due to long-standing groin pain. A secondary purpose was evaluating the frequency of femoro-acetabular impingement (FAI) and its impact on the long-term outcome.

Methods

Thirty-two high-level male athletes treated with adductor tenotomy, rectus abdominis tenotomy or both were included. At a median follow-up time of 6 years after the tenotomy, the subjects underwent standardised clinical examination, plain radiographs, completed web-based health-related patient-reported outcomes, including iHOT12, HAGOS (six subscales), EQ-5D (two subscales), HSAS for physical activity level and a VAS for overall hip function. Furthermore, patient satisfaction and return to sports were documented.

Results

Twenty-four of the 32 (75 %) athletes were satisfied with the outcome of the tenotomy, and 22 of the athletes (69 %) were able to return to their pre-injury sport. Before the long-term follow-up, two of these satisfied athletes had undergone repeat surgery (one hip arthroscopy due to FAI and one repeat tenotomy). Of the 24 satisfied athletes, eight (33 %) had a positive hip impingement test at the follow-up. Of the remaining eight athletes not satisfied with the outcome, only one returned to their pre-injury sport and three had undergone hip arthroscopy prior to follow-up. Five had positive hip impingement tests which was significantly more frequently than in the satisfied group (p = 0.008). The group with a positive hip impingement test reported significantly more pain and symptoms, more hip problems during sports and physical activity, as well as lower hip-related quality of life according to the HAGOS scores (p < 0.05), at follow-up.

Conclusion

Tenotomy for pubalgia yielded a satisfactory long-term outcome, with three of four athletes being able to return to their pre-injury sport. The athletes that did not return to their pre-injury sport had higher frequency of positive hip impingement test and inferior functional outcome compared with the athletes that did return to their pre-injury sport. It is therefore recommended that the hip should be carefully evaluated for hip impingement before tenotomy is considered as treatment for athletes with pubalgia.

Level of evidence

Retrospective case series, Level IV.     

Can facial proportions taken from images be of use for ageing in cases of suspected child pornography? A pilot study

The age of the victim plays a crucial role for the legal implications concerning pornography. Judges therefore often call on forensic experts to verify the age of individuals depicted on photographs or videos. However, there is no scientifically established protocol available for forensic practice in such cases. The conventional methods such as the evaluation of secondary sexual characteristics provide unsatisfactory results particularly when the legally relevant ages for child pornography (i.e. 14 and 18 years) are concerned. To overcome these limits, a European research group has explored the applicability of facial proportions as an age indicator on images. In this pilot study, standardized facial images of 353 females and 20 males from four age groups (6, 10, 14 and 18 years) were randomly selected for the metric analysis from a large data set including German, Italian and Lithuanian subjects. In this sample, several indices extracted from the frontal and lateral photographs were closely correlated to their respective indices taken from the living individuals. Furthermore, age-related changes were identified for indices taken from the photographs. The discriminant analysis showed that for the pooled sample, 60.3% of the cases were correctly classified into the respective age group. The percentage of correctly classified cases increased in the respective country samples as follows: 69.9% for Germany, 69.4% for Lithuania and 80.5% for Italy. The present study suggests that the metric assessment of the face may be used for age estimation on images. Nonetheless, more work needs to be done in order to verify the reliability of these findings on a large sample.     

Can virtual non-enhanced CT be used to replace true non-enhanced CT for the detection of palpable cervical lymph nodes? A preliminary study

Purpose

To investigate the potential of virtual non-contrast CT (VNCT) from dual-energy CT to replace true nonenhanced CT (TNCT) for the detection of enlarged cervical lymph nodes.

Materials and methods

Thirty-nine patients with 94 histopathologically proven cervical lymph nodes were imaged with the dual-energy CT technique. VNCT images from the arterial [VNCT-A] and venous phases [VNCT-V] were obtained with the liver VNC application. The mean CT number and signal-to-noise ratio (SNR) were compared. Image quality was evaluated with a score scale of 1–5. Effective dose (ED) was calculated and compared.

Results

Mean CT numbers of cervical lymph nodes were higher on VNCT than on TNCT (P = 0.034). There was no difference in the SNR among three sets of non-enhanced CT images, but the CNR of VNCT images was higher than that of TNCT images (P < 0.001). Image quality of VNCT from two phases was comparable to that of TNCT (P = 0.070). There was no difference in image quality of three sets of non-enhanced CT images (P > 0.05). ED from dual-phase dual-energy CT was lower than that from tri-phase CT scans (P < 0.001).

Conclusion

VNCT images from dual-energy CT of the neck had diagnostic image quality; they have the potential to replace TNCT, thus reducing the radiation dose.     

Is E-mail Communication Effective in Changing Ordering Patterns in the Emergency Department?: A Case Study of Computed Tomography for Pulmonary Embolus

RATIONALE AND OBJECTIVES: We sought to evaluate the effectiveness of e-mail communication to reduce the utilization of computed tomography for pulmonary thromboembolism (PE) in young patients (aged 40 and under) in our institution. MATERIALS AND METHODS: An e-mail was sent to all of our institution's emergency department (ED) physicians in response to a series of negative PE studies in young females. The periods 90 days before and 90 days after were evaluated to assess the total number of PE studies performed in patients aged 40 and younger, the rate of positivity, and the utilization of D-dimer and ventilation/perfusion scans during each period. RESULTS: Over the 180-day period, a total of 65 PE studies were ordered in patients aged 40 and younger in the ED. Studies were positive for PE in 1 of 33 (3%) before the e-mail and 4 of 32 (12.5%) after (P = .343). There was no difference in the number of D-dimer studies ordered during each period for patients studied with computed tomography. Ventilation/perfusion scanning was not performed on any ED patients younger than 40 during the 180-day period. CONCLUSIONS: One-time e-mail communication was not effective in changing ED ordering habits of PE studies. Scant information exists in regard to effective clinician-to-clinician communication. Further evaluation for successful mechanisms to promote health practice reform and quality improvement is necessary.     

Can a state-of-the-art D-dimer test be used to determine the need for CT imaging in patients suspected of having pulmonary embolism?

RATIONALE AND OBJECTIVES: The purpose of this study was to determine whether a simple rapid blood test can obviate computed tomography (CT) in a sizable percentage of patients suspected of having pulmonary embolism, based on the hypothesis that negative D-dimer results could eliminate any further search for pulmonary embolism. MATERIALS AND METHODS: At the authors' institution, 2,121 sequential patients underwent a whole-blood antibody agglutination test for cross-linked fibrin degradation products (D-dimer). Of these patients, 844 had positive test results and were not further considered. A retrospective review included reports of all multisection combined CT venographic and pulmonary angiographic studies obtained within 48 hours of the D-dimer assay for the 1,277 patients with negative D-dimer results; 229 (18%) of these 1,277 patients underwent combined CT venography and pulmonary angiography, usually within 24 hours. RESULTS: Retrospective review of the imaging examinations that were discrepant with the D-dimer results revealed only three false-negative D-dimer results. Of the 229 patients in whom combined CT venography and pulmonary angiography was performed for suspected pulmonary embolism, 226 (98.7%) had no evidence of acute pulmonary embolism or deep venous thrombosis. The negative predictive value of a negative D-dimer result was therefore 98.7% (confidence interval, 96.2%-99.7%). CONCLUSION: The D-dimer assay is a simple rapid blood test that is sensitive to the presence of acute thrombosis. Very few patients with negative results have acute deep venous thrombosis or pulmonary embolism, with combined CT venography and pulmonary angiography used as the reference standard.     

Can [18F]fluorodeoxyglucose positron emission tomography imaging complement biopsy results from the iliac crest for the detection of bone marrow involvement in patients with malignant lymphoma?

OBJECTIVES: To assess the usefulness of [18F]fluorodeoxyglucose positron emission tomography in the detection of bone marrow involvement in malignant lymphoma, and its impact in clinical management. METHODS: One hundred and six consecutive patients with a confirmed diagnosis of lymphoma, referred for staging or restaging of Hodgkin's lymphoma (n=18) or non-Hodgkin's lymphoma (n=88), were reviewed retrospectively. A positron emission tomography scan and bone marrow biopsy of the iliac crest were performed in all patients. The assessment of bone marrow involvement by lymphoma was confirmed by histology and/or progression of bone marrow lesions in clinical follow-up. RESULTS: In 28 of 106 patients, bone marrow involvement was found. Positron emission tomography was more sensitive (86%) than bone marrow biopsy (57%). Positron emission tomography and bone marrow biopsy were concordant by positive correlation in 12 of 28 cases (43%) and by negative correlation in 77 of 78 cases (99%). Ten cases of non-Hodgkin's lymphoma and two cases of Hodgkin's lymphoma with positive positron emission tomography results and an initial negative bone marrow biopsy showed clinical progression of the bone marrow lesions and/or subsequent positive histology. These were considered as false-negative results for bone marrow biopsy. In seven of the 12 positive cases with negative bone marrow biopsy, positron emission tomography uptake distant from the site of the biopsy was seen. In four cases of follicular lymphoma, the bone marrow biopsy was positive and the positron emission tomography scan was normal. CONCLUSIONS: Positron emission tomography and bone marrow biopsy are complementary in assessing the presence of bone marrow involvement in patients with malignant lymphoma. In our series, positron emission tomography was more sensitive than bone marrow biopsy in Hodgkin's and non-Hodgkin's lymphoma, except in follicular lymphoma.