Relationship between bone bruise volume and the presence of meniscal tears in acute anterior cruciate ligament rupture

Purpose

To determine whether there is a relationship between the size of the bone bruise volume after an acute anterior cruciate ligament (ACL) rupture and the presence of meniscal tears in the medial and lateral compartment.

Methods

Following Institutional Review Board approval, 50 patients with an acute ACL rupture and MRI imaging within 30 days of injury were identified. Two musculoskeletal radiologists evaluated the lateral and medial menisci and graded them as one of the following: no meniscal tear, tear of one meniscus (medial or lateral) or tear of both menisci (medial and lateral). Sagittal T2 fat-suppressed images were used to calculate bone bruise volume. The relationship between bone bruise volume and the presence of a meniscus tear was calculated.

Results

Forty-three (86 %) patients had a bone bruise, 16 (32 %) patients had no tear, 7 (14 %) patients had lateral meniscus tear, 13 (26 %) patients had medial tear and 14 (28 %) patients had medial and lateral tears. There was a statistically significant difference in femoral bone bruise volume when comparing no meniscal tear to medial and lateral tears as well as when comparing medial or lateral tears to medial and lateral tears.

Conclusion

There is a statistically significant relationship between femoral bone bruise volume and the presence of meniscal tears in ACL injury, especially in the setting of medial and lateral pathology.

Level of evidence

Retrospective cohort study, Level III.     

Bony morphology of the knee and non-traumatic meniscal tears: Is there a role for meniscal impingement?

Objective

Meniscal tears are an important cause of morbidity. The aim of this study was to examine the relationship between non-traumatic meniscal tears and the intrinsic bony morphology of the knee.

Methods

A retrospective analysis of 160 knee MRI scans in 150 patients was carried out who met the following criteria: (a) age between 20 and 45 years, (b) no history of knee trauma, surgery, infection, metabolic bone disease, and (c) no collateral or cruciate ligamentous injury. The medial tibial slope (MTS), lateral tibial slope (LTS), medial tibial plateau depth (MTPD), and medial and lateral femoral condylar offset ratios were calculated. The anterior horn, body, and posterior horn of the menisci were graded as 0 (no tear), 1 and 2 (degenerative changes), or 3 (definitive tear). One-way ANOVA and linear regression was used for statistical analysis.

Results

In patients with grade 3 tears of the posterior horn of the medial meniscus, there was a significant association with shallower MTS (p?<?0.05), smaller medial femoral offset ratio (p?<?0.05) and smaller lateral femoral offset ratio (p?<?0.05). Patients with grade 3 tears of anterior horn of the lateral meniscus had a significant association with shallower LTS (p?<?0.05). No significant association was seen between MTPD and meniscal tears.

Conclusions

Our results suggest an association between bony morphology of the knee and non-traumatic meniscal tears. Shallower MTS and LTS may result in impingement of posterior horn of medial meniscus and anterior horn of lateral meniscus, respectively. Future kinematic studies will be needed to help confirm our findings.     

The shiny corner of the knee: a sign of meniscal osteochondral unit dysfunction

Objective

The purpose of this retrospective study is to describe the MRI findings of the “shiny corner” of the knee (bone marrow lesions at the meniscal-covered portions of the tibial plateau) and to determine its association with compromise of the medial meniscal-osteochondral unit.

Materials and methods

A retrospective review of 200 knee MRI exams was performed and images were evaluated in consensus by two musculoskeletal radiologists. Presence and location of a shiny-corner lesion was recorded, which was defined as a focal, peripheral hyperintense lesion on fluid-sensitive images at the superior portion of the medial tibial plateau. Meniscal and root ligament abnormalities were recorded, including tearing, degeneration, and extrusion.

Results

Sixty exams demonstrated a shiny-corner lesion. Shiny corners involved the medial rim of the medial tibial plateau in 50 cases, only involved the posterior rim in seven cases, and only involved the anterior rim in two cases. Patients with shiny corners were older than patients without shiny corners (mean, 53 years vs. 44 years, p?=?0.01). The shiny-corner sign was associated with tears of the medial meniscus, root ligament, and meniscal extrusion (p?Conclusions Shiny-corner lesions of the knee are associated with tears of the menisci and root ligaments. This observation supports the concept that the menisci protect the underlying covered portions of the tibial plateau.     

Obesity increases the prevalence and severity of focal knee abnormalities diagnosed using 3T MRI in middle-aged subjects—data from the Osteoarthritis Initiative

Objective

To study the effect of BMI on the prevalence, severity, and 36-month progression of early degenerative changes in the knee by using 3T MRI in middle-aged subjects without radiographic osteoarthritis (OA).

Materials and methods

We examined baseline and 36-month follow-up MR studies from 137 middle-aged individuals (45-55 years old) with risk factors for knee OA but no radiographic OA from the Osteoarthritis Initiative. Subjects were grouped into three categories: normal BMI (BMI?2, n?=?38), overweight (BMI 25–29.9 kg/m², n?=?37), and obese (BMI ≥ 30 kg/m², n?=?62). Using 3T MRI, cartilage, meniscus, and bone marrow abnormalities were graded using the OA Whole-organ MR Imaging Score (WORMS). The statistical analysis was corrected as necessary for differences in age, sex, and OA risk factors other than BMI.

Results

The overall prevalence of lesions was 64% for meniscus and 79% for cartilage (including low grade lesions). At baseline, the prevalence and severity of knee lesions was positively associated with BMI, with a nearly fourfold increase in meniscal tears and more than twofold increase in high-grade cartilage defects in obese individuals relative to normal-weight subjects. Over the 36-month follow-up period, the number of new or worsening cartilage lesions of any grade was significantly higher in obese subjects (p?=?0.039), while there was no significant difference in meniscal lesion progression.

Conclusion

Obesity was associated with both higher prevalence and severity of early degenerative changes in the knee in middle-aged individuals without radiographic OA and with significantly increased cartilage lesion progression (of any grade) over 36 months.     

Medial meniscal root tears and meniscal extrusion transverse length ratios on MRI

Objective

To evaluate the clinical utility of the meniscal extrusion transverse ratio of the medial meniscus in the diagnosis of meniscal root tear compared with the gold standard of arthroscopic diagnosis.

Methods

This retrospective study sample included 32 males and 35 females who underwent MRI at our institution. There were 24 meniscal root tear cases. The control groups were 18 cases of medial meniscal tears without root tears and 25 cases of negative meniscal findings on arthroscopy. Meniscal extrusion (L) and maximal transverse lengths (T) of the medial meniscus were measured, and L/T ratios were calculated. These results were correlated with arthroscopic findings and analysed statistically. With arthroscopic findings used as the standard of reference, the sensitivity and specificity of 10%, 11% and 12% extrusion thresholds, and 3 mm of medial meniscal extrusion (MME) as diagnostic thresholds, were calculated.

Results

The mean length of the meniscal extrusions of meniscal root tears was twice as long as the control group. The mean L/T ratio of the meniscal root tears was approximately 13%, while those of the control groups were 5%. The differences in the L and L/T between the meniscal root tears and normal and meniscal root tears and other meniscal tears were statistically significant (p<0.001), but those between normal and other meniscal tears were not. The best diagnostic discrimination was achieved using an extrusion ratio threshold of 10% (79% sensitivity, 86% specificity). The 3 mm of MME threshold demonstrated high specificity (98%), but not high sensitivity (54%).

Conclusion

The mean L/T ratio of the meniscal root tears was approximately 13% and was statistically significant. The best diagnostic discrimination was achieved using an extrusion ratio threshold of 10%.

Advances in knowledge

The use of the L/T ratio in combination with MME can be a useful method for evaluating medial meniscal root tears.The meniscal roots are the sites where the knee meniscus attaches to the central tibial plateau [1]. In many cases, a meniscal root tear is not prominent on a single MRI image as the structures follow oblique courses. Medial meniscal extrusion (MME) is a significant medial displacement of the medial meniscus with respect to the central margin of the medial tibial plateau and is closely associated with medial meniscal root tears (MMR) [2]. The meniscus is considered “extruded” when it extends beyond the tibial margin; this results from disruption of collagen fibres within the meniscus that provide hoop strength [3]. The critical length of extrusion is approximately 3 mm [4-5]. There is some uncertainty regarding the length of the extrusion because the transverse diameter of the medial meniscus varies with age and individual; uniform length criteria can be replaced with length ratios. The current study was performed to evaluate the clinical utility of the meniscal extrusion transverse ratio of the medial meniscus in the diagnosis of the meniscal root tears as compared with the gold standard of arthroscopic diagnosis.     

Meniscal T1rho and T2 measured with 3.0T MRI increases directly after running a marathon

Purpose

To prospectively evaluate changes in T1rho and T2 relaxation time in the meniscus using 3.0?T MRI in asymptomatic knees of marathon runners and to compare these findings with those of age-matched healthy subjects.

Material and methods

Thirteen marathon runners underwent 3.0?T MRI including T1rho and T2 mapping sequences before, 48?C72?h after, and 3?months after competition. Ten controls were examined at baseline and after 3?months. All images were analyzed by two musculoskeletal radiologists identifying and grading cartilage, meniscal, ligamentous. and other knee abnormalities with WORMS scores. Meniscal segmentation was performed to generate T1rho and T2 maps in six compartments.

Results

No differences in morphological knee abnormalities were found before and after the marathon. However, all marathon runners showed a significant increase in T1rho and T2 values after competition in all meniscus compartments (p?Conclusion T2 values in menisci have the potential to be used as biomarkers for identifying reversible meniscus matrix changes indicating potential tissue damage. T1rho values need further study, but may be a valuable marker for diagnosing early, degenerative changes in the menisci following exercise.     

Delayed gadolinium-enhanced MRI of the meniscus (dGEMRIM) in patients with knee osteoarthritis: relation with meniscal degeneration on conventional MRI,reproducibility, and correlation with dGEMRIC

Objectives

To assess (1) whether normal and degenerated menisci exhibit different T1_GD on delayed gadolinium-enhanced MRI of the meniscus (dGEMRIM), (2) the reproducibility of dGEMRIM and (3) the correlation between meniscus and cartilage T1_GD in knee osteoarthritis (OA) patients.

Methods

In 17 OA patients who underwent dGEMRIM twice within 7 days, meniscus and cartilage T1_GD was calculated. Meniscus pathology was evaluated on conventional MRI. T1_GD in normal and degenerated menisci were compared using a Student’s t-test. Reproducibility was assessed using ICCs. Pearson’s correlation was calculated between meniscus and cartilage T1_GD.

Results

A trend towards lower T1_GD in degenerated menisci (mean: 402 ms; 95 % CI: 359–444 ms) compared to normal menisci (mean: 448 ms; 95 % CI: 423–473 ms) was observed (p?=?0.05). Meniscus T1_GD ICCs were 0.85–0.90. The correlation between meniscus and cartilage T1_GD was moderate in the lateral (r?=?0.52–0.75) and strong in the medial compartment (r?=?0.78–0.94).

Conclusions

Our results show that degenerated menisci have a clear trend towards lower T1_GD compared to normal menisci. Since these results are highly reproducible, meniscus degeneration may be assessed within one delayed gadolinium-enhanced MRI simultaneously with cartilage. The strong correlation between meniscus and cartilage T1_GD suggests concomitant degeneration in both tissues in OA, but also suggests that dGEMRIC may not be regarded entirely as sulphated glycosaminoglycan specific.

Key Points

? dGEMRIM T1 _GD can possibly be used to assess meniscal degeneration; ? dGEMRIM yields highly reproducible meniscal T1 _GD in early stage osteoarthritic patients; ? Concomitant degeneration of cartilage and meniscus tissue occurs in early stage osteoarthritis; ? dGEMRIC cannot be regarded as entirely sulphated glycosaminoglycan specific.     

Reliability of magnetic resonance imaging in evaluating meniscal and cartilage injuries in anterior cruciate ligament-deficient knees

Purpose

The accuracy of magnetic resonance (MR) imaging in assessing meniscal and cartilage injuries in anterior cruciate ligament (ACL)-deficient knees as compared to arthroscopy was evaluated in the present study.

Methods

The results of all preoperative MR imaging performed within 3 months prior to the ACL reconstruction were compared against intraoperative arthroscopic findings. A total of 206 patients were identified. The location and type of meniscal injuries as well as the location and grade of the cartilage injuries were studied. The negative predictive value, positive predictive value, sensitivity, specificity and accuracy of MR imaging for these 206 cases were calculated and analysed.

Results

In patients with an ACL injury, the highest incidence of concomitant injury was that of medial meniscus tears, 124 (60.2 %), followed by lateral meniscus tears, 105 (51.0 %), and cartilage injuries, 66 (32.0 %). Twenty-three (11.2 %) patients sustained injuries to all of the previously named structures. MR imaging was most accurate in detecting medial meniscus tears (85.9 %). MR imaging for medial meniscus tears also had the highest sensitivity (88.0 %) and positive predictive value (88.7 %), while MR imaging for cartilage injuries had the largest specificity (84.1 %) and negative predictive value (87.1 %). It was least accurate in evaluating lateral meniscus tears (74.3 %). The diagnostic accuracy of medial meniscus imaging is significantly influenced by age and the presence of lateral meniscus tears, while the duration between MR imaging and surgery has greater impact on the likelihood of lateral meniscus and cartilage injuries actually being present during surgery. The majority of meniscus tears missed by MR imaging affected the posterior horn and were complex in nature. Cartilage injuries affecting the medial femoral condyle or medial patella facet were also often missed by MR imaging.

Conclusion

MR imaging remains a reliable tool for assessing meniscus tears and cartilage defects preoperatively. It is most accurate when evaluating medial meniscus tears. However, MR imaging should be used with discretion especially if there is a high index of suspicion of lateral meniscus tears.

Level of evidence

IV.

     

The MRI findings of meniscal root tear of the medial meniscus: emphasis on coronal, sagittal and axial images

Purpose

The purpose of this study was to evaluate the accuracy of the characteristic magnetic resonance imaging (MRI) findings of medial meniscal root tear in the coronal, sagittal and axial planes.

Methods

Thirty arthroscopically diagnosed patients who had undergone preoperative knee MRI were included in this study. They were compared to 30 age-matched patients with medial meniscus tears without root tears. The findings used for imaging analysis were as follows: the radial tear on the meniscal root of the medial meniscus in the axial plane, the presence of the truncation sign in the coronal plane and the ghost meniscus sign in the sagittal plane. Meniscal extrusion in the coronal plane was also evaluated. All the MRI findings of both groups were statistically analyzed.

Results

All the findings were more frequently found in the root tear group than those in the control group (P < 0.05). The sensitivity, specificity, positive predictive value and negative predictive value of finding a radial tear in the axial plane were 93.3, 100, 100 and 93.8%, respectively. In the coronal plane, rates for the presence of the truncation sign were 90, 100, 100 and 90.9%, respectively. In the sagittal plane, rates for the presence of the ghost meniscus sign were 96.7, 96.7, 96.7 and 96.7%, respectively. The rates for the meniscus extrusion in the coronal plane were 63.3, 90, 86.4 and 71.1%, respectively.

Conclusions

The findings of medial meniscal root tear were characteristic as compared with the control group. Radial tear in the axial plane also showed similar diagnostic accuracy as that seen in the other planes. The characteristic findings provide high diagnostic accuracy, and axial plane is helpful to detect medial meniscal root tear.

Level of evidence

Diagnostic study, Level III.     

Fat-suppressed volume isotropic turbo spin echo acquisition (VISTA) MR imaging in evaluating radial and root tears of the meniscus: Focusing on reader-defined axial reconstruction

Objective

To assess the diagnostic value of fat-suppressed (FS) three-dimensional (3D) volume isotropic turbo spin echo acquisition (VISTA) imaging in detecting radial and root tears of the meniscus, including the reader-defined reformatted axial (RDA) plane.

Materials and methods

Twenty-three patients with arthroscopically confirmed radial or root tears of the meniscus underwent magnetic resonance imaging (MRI) with 2D and FS 3D VISTA sequences. MRIs were reviewed independently by two musculoskeletal radiologists blinded to the arthroscopic findings. Sensitivity, specificity, accuracy, and interobserver agreement were calculated for radial and root tears. Both radiologists reported confidence scale for the presence of meniscal tears in 2D axial imaging, 3D axial imaging, and RDA imaging, based on a five-point scale. Wilcoxon's signed rank test was used to compare confidence scale.

Results

The sensitivity, specificity, and accuracy of FS 3D VISTA MR imaging versus 2D MR imaging were as follows: 96%, 96%, and 96% versus 91%, 91%, and 91%, respectively in reader 1, and 96%, 96%, and 96% versus 83%, 91%, and 87%, respectively, in reader 2. Interobserver agreement for detecting meniscal tears was excellent (κ = 1) with FS 3D VISTA. The confidence scale was significantly higher for 3D axial images than 2D imaging (p = 0.03) and significantly higher in RDA images than 3D axial image in detecting radial and root tears.

Conclusions

FS 3D VISTA had a better diagnostic performance in evaluating radial and root tears of the meniscus. The reader-defined reformatted axial plane obtained from FS 3D VISTA MR imaging is useful in detecting radial and root tears of the meniscus.     

Arthroscopic inside-out repair of complete radial tears of the meniscus with a fibrin clot

Purpose

To report on the results of 12 complete radial tears of the meniscus treated using arthroscopic inside-out repair with fibrin clots, the results showed good meniscal healing and excellent clinical outcomes.

Methods

From 2007 to 2009, 12 patients with complete radial tears of the meniscus were treated by arthroscopic inside-out repair with fibrin clots. In all patients, the International Knee Documentation Committee (IKDC) subjective knee form and Lysholm score were determined pre- and post-operatively. We performed magnetic resonance imaging (MRI) and if indicated, we performed a second-look arthroscopic examination.

Results

At a mean of 30 ± 4 postoperative months, the Lysholm score and IKDC subjective knee score had improved from 65 ± 6 and 57 ± 7 to 94 ± 3 and 92 ± 3, respectively. Eleven of 12 cases showed complete healing on follow-up MRI. Six of 7 patients undergoing a second-look arthroscopic examination had healed completely.

Conclusion

This study shows successful meniscal repairs using fibrin clots in complete radial tears. This surgical procedure appears to be a good treatment method for complete radial tear of the meniscus.

Level of evidence

Case series, Level IV.     

The degree of articular depression as a predictor of soft-tissue injuries in tibial plateau fracture

Purpose

Magnetic resonance imaging (MRI) provides sufficient information with regard to specific soft-tissue injuries in the knee, but it is not generally used to evaluate acute tibial plateau fractures. The aim of the present study was to determine whether the amount of tibial plateau fracture depression on multi-detector computed tomography (MDCT) scans correlates with the incidence of associated soft-tissue injuries on MRI.

Methods

A total of 54 consecutive patients with a mean age of 51.2 years (SD = 18.3) were included in this retrospective study. All patients were admitted to the emergency department of a university clinic with acute tibial plateau fracture. The amount of articular depression was assessed from MDCT scans. Magnetic resonance images were evaluated for crucial and collateral ligament injury, meniscal tears, and patellar retinaculum lesions.

Results

Logistic regression revealed a significant impact of increasing tibial plateau fracture depression on the incidence of meniscus lateralis tears (P = 0.025) and anterior cruciate ligament lesions (P = 0.018). Analysis of covariance demonstrated a significant correlation between the amount of articular depression and absolute number of soft-tissue injuries (P = 0.001).

Conclusions

Articular depression is a potential predictor of specific meniscal and ligamentous injuries in acute tibial plateau fracture. Magnetic resonance imaging is generally recommended with respect to associated soft-tissue injuries, especially in cases with distinct tibial plateau fracture depression on multi-detector computed tomography scans.

Level of evidence

Case series, Level IV.     

Meniscus surgery is still widely performed in the treatment of degenerative meniscus tears in The Netherlands

Purpose

Studies have demonstrated rising incidences of meniscus procedures for degenerative meniscus tears in several countries, despite accumulating evidence that questions the efficacy of the treatment. It is not clear if this rise in incidences also applies to the practice of arthroscopic surgery in the Netherlands. The objective of this study was, therefore, to evaluate the number of meniscal surgeries performed in the Netherlands between 2005 and 2014.

Methods

We used registry-based data on meniscal surgeries that originated from Dutch national hospital basic care registrations from 2005 to 2014. Poisson regression models were used to test differences in incidences of meniscus surgeries performed in the Netherlands between 2005 and 2014, and to find out if changes in incidences over this period differed for younger and older patients.

Results

The number of meniscus surgeries was highest in patients aged 40–65 years, who accounted for half of the total number of meniscal surgeries. The incidences of meniscus surgeries decreased from 2005 to 2014 (p?<?0.001); this decrease was observed in all age groups, although the decrease in incidences was more pronounced for younger patients (aged less than 40 years) compared to middle-aged and older patients (aged 40 years and older) (p?<?0.001).

Conclusions

The implementation of a nationwide guideline for arthroscopic procedures for meniscus tears may have contributed to a decrease in incidences of meniscus procedures. Despite accumulating evidence that questions the rationalisation and effectiveness of the treatment, meniscus surgery is still widely performed in the treatment of degenerative meniscus tears in the Netherlands, demonstrating a delay in the dissemination, acceptance, and implementation of clinical evidence in the practice of arthroscopic surgery in the Netherlands.

Level of evidence

II.

     

Impact of iterative reconstruction on CNR and SNR in dynamic myocardial perfusion imaging in an animal model

Objectives

To evaluate a new iterative reconstruction (IR) algorithm for radiation dose, image quality (IQ), signal-to-noise-ratio (SNR), and contrast-to-noise-ratio (CNR) in multidetector computed tomography (MDCT) dynamic myocardial perfusion imaging (MPI).

Methods

ECG-gated 256-slice MDCT dynamic MPI was performed in six pigs after subtotal balloon occlusion of one artery. Two 100 kVp protocols were compared: high dose (HD): 150 mAs; low dose (LD): 100 mAs. HD images were reconstructed with filtered back projection (FBP), LD images with FBP and different strengths of IR (L1, L4, and L7). IQ (5-point scale), SNR, and CNR (ischemic vs. normal myocardium) values derived from the HD (FBP) images and the different LD images were compared.

Results

Mean SNR values for myocardium were 16.3, 11.3, 13.1, 17.1, and 28.9 for the HD, LD (FBP), LD (L1), LD (L4), and LD (L7) reconstructions, respectively. Mean CNR values were 8.9, 6.3, 7.8, 9.3, and 12.8. IQ was scored as 4.6, 3.3, 4.4, 4.7, and 3.4, respectively. A significant loss of IQ was observed for the LD (L7) images compared to the HD (FBP) images (P?<?0.05).

Conclusion

Appropriate levels of iterative reconstruction can improve SNR and CNR, facilitating radiation dose savings in CT-MPI without influencing diagnostic quality.

Key Points

? Iterative reconstruction (IR) can reduce radiation dose in myocardial perfusion CT. ? Our study also demonstrated improvements in image quality (noise, SNR, and CNR). ? Dynamic CT-MPI could help determine the hemodynamic significance of coronary artery disease. ? With dynamic CT MPI, myocardial blood flow can be determined quantitatively.     

Magnetic resonance imaging of ankle tendon pathology: benefits of additional axial short-tau inversion recovery imaging to reduce magic angle effects

Objectives

Our goals were to quantify the reduction of the magic angle effect using short-tau inversion recovery (STIR) imaging and to determine the value of adding an axial STIR sequence to the magnetic resonance imaging ankle protocol.

Materials and methods

Axial STIR sequences were used to measure normal tendon T1 and to estimate signal loss due to the inversion recovery preparation of our clinical protocol. In addition, 102 ankles were imaged with axial fat-suppressed intermediate-weighted fast spin echo and STIR sequences. Two radiologists analyzed the tendons for signal intensity, size, abnormalities, and magic angle effect. The diagnostic value and image quality of the two sequences were compared.

Results

We calculated a 50 % reduction of signal intensity in healthy tendons on the STIR sequence at TI?=?170 ms compared with TI?=?0 ms, explaining the decrease in the magic angle effect. Using the STIR sequence, our study demonstrated significantly lower signal intensity within the tendons, more precise tendon size, and a lower magic angle effect compared with the standard intermediate-weighted FSE sequence (p?<?0.001). Diagnostic classification of tendon abnormalities using the STIR sequences showed higher sensitivity (82.35 % vs 75.27 %) and better agreement with a reference standard than the intermediate-weighted sequences, and superior image quality (p?<?0.01).

Conclusions

Axial STIR sequences reduce magic angle effects and improve visualization of ankle tendon pathology.     

Thrombus imaging in acute ischaemic stroke using thin-slice unenhanced CT: comparison of conventional sequential CT and helical CT

Objectives

Thin-slice helical unenhanced CT can be used for thrombus imaging but increases radiation exposure. Conventional sequential images obtained by multidetector CT can be reconstructed into thin-slice images. The purpose of this study was to evaluate if conventional sequential unenhanced CT images can replace helical unenhanced CT for thrombus imaging.

Methods

Fifty consecutive patients with acute ischaemic stroke underwent both 5-mm conventional sequential unenhanced CT and helical unenhanced CT. Each of the sequential and helical unenhanced CT images was subsequently reconstructed into four 1.25-mm images. Thrombus volumes and HU were measured semi-automatically using both types of unenhanced CT. Thrombus HU ratio (rHU) was calculated using the HU of the contralateral segment. The intraclass correlation coefficient (ICC) and Bland–Altman plots were used to assess measurement agreement.

Results

The mean rHUs were 1.47?±?0.17 for sequential unenhanced CT and 1.47?±?0.18 helical unenhanced CT (P?=?0.542). The mean thrombus volumes were 124.25?±?125.65?mm³ and 117.84?±?124.32?mm³ on sequential and helical unenhanced CT images, respectively (P?=?0.063). Measurement agreement between thrombus volumes from the two unenhanced CT images was high (ICC?=?0.981).

Conclusions

Thin-slice unenhanced CT images reconstructed from 5-mm sequential images can replace helical unenhanced CT for thrombus imaging in acute ischaemic stroke.

Key Points

? Unenhanced CT is used to evaluate intra-arterial thrombus. ? Thrombus HU and volume measurements using sequential or helical CT are comparable. ? Conventional sequential images can replace helical CT for thrombus imaging. ? Radiation dose for thrombus imaging can be reduced using sequential CT.     

Anterolateral ligament abnormalities in patients with acute anterior cruciate ligament rupture are associated with lateral meniscal and osseous injuries

Objective

To determine the frequency of anterolateral ligament (ALL) injury in patients with acute anterior cruciate ligament (ACL) rupture and to analyse its associated injury patterns.

Methods

Ninety patients with acute ACL rupture for which MRI was obtained within 8 weeks after the initial trauma were retrospectively identified. Two radiologists assessed the status of the ALL on MRI by consensus. The presence or absence of an ALL abnormality was compared with the existence of medial and lateral meniscal tears diagnosed during arthroscopy. Associated collateral ligament and osseous injuries were documented with MRI.

Results

Forty-one of 90 knees (46 %) demonstrated ALL abnormalities on MRI. Of 49 knees with intact ALL, 15 (31 %) had a torn lateral meniscus as compared to 25 torn lateral menisci in 41 knees (61 %) with abnormal ALL (p?=?0.008). Collateral ligament (p?≤?0.05) and osseous injuries (p?=?0.0037) were more frequent and severe in ALL-injured as compared with ALL-intact knees.

Conclusion

ALL injuries are fairly common in patients with acute ACL rupture and are statistically significantly associated with lateral meniscal, collateral ligament and osseous injuries.

Key Points

? ALL injuries are fairly common in patients with acute ACL rupture. ? ALL injuries are highly associated with lateral meniscal and osseous injuries. ? MRI assessment of ACL-injured knees should include evaluation of the ALL.

     

Cardiac MRI: evaluation of phonocardiogram-gated cine imaging for the assessment of global und regional left ventricular function in clinical routine

Objectives

To validate a phonocardiogram (PCG)-gated cine imaging approach for the assessment of left ventricular (LV) function.

Methods

In this prospective study, cine MR imaging of the LV was performed twice in 79 patients by using retrospectively PCG- and retrospectively ECG-gated cine SSFP sequences at 1.5?T. End-diastolic volumes (EDV), end-systolic volumes (ESV), stroke volumes (SV), ejection fraction (EF), muscle mass (MM), as well as regional wall motion were assessed. Subgroup analyses were performed for patients with valvular defects and for patients with dysrhythmia.

Results

PCG-gated imaging was feasible in 75 (95%) patients, ECG-gating in all patients. Excellent correlations were observed for all volumetric parameters (r?>?0.98 for all variables analysed). No significant differences were observed for EDV (?0.24?±?3.14?mL, P?=?0.5133), ESV (?0.04?±?2.36?mL, P?=?0.8951), SV (?0.20?±?3.41?mL, P?=?0.6083), EF (?0.16?±?1.98%, P?=?0.4910), or MM (0.31?±?4.2?g, P?=?0.7067) for the entire study cohort, nor for either of the subgroups. PCG- and ECG-gated cine imaging revealed similar results for regional wall motion analyses (115 vs. 119 segments with wall motion abnormalities, P?=?0.3652).

Conclusion

The present study demonstrates that PCG-gated cine imaging enables accurate assessment of global and regional LV function in the vast majority of patients in clinical routine.

Key Points

• Phonocardiogram-gating is an alternative to electrocardiographic-gating in cardiac MR.
• Phonocardiogram-gated imaging allows reliable assessment of global and regional left-ventricular function.
• Phonocardiogram-gating is feasible in patients with valvular lesions or cardiac dysrhythmia.
• Because phonocardiogram-gating is insensitive to magneto-hydrodynamic effects, it is suitable for ultra-high field.

     

Reduced radiation dose and improved image quality at cardiovascular CT angiography by automated attenuation-based tube voltage selection: intra-individual comparison

Objectives

To evaluate the effect of automated tube voltage selection on radiation dose and image quality at cardiovascular CT angiography (CTA).

Methods

We retrospectively analysed paired studies in 72 patients (41 male, 60.5?±?16.5 years), who had undergone CTA acquisitions of the heart or aorta both before and after the implementation of an automated x-ray tube voltage selection algorithm (ATVS). All other parameters were kept identical between the two acquisitions. Subjective image quality (IQ) was rated and objective IQ was measured by image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and figure of merit (FOM). Image quality parameters and effective dose were compared between acquisitions.

Results

Overall subjective image quality improved with the percentage of cases scored as adequate or higher increasing from 79 % to 92 % after implementation of ATVS (P?=?0.03). SNR (14.1?±?5.9, 15.7?±?6.1, P?=?0.009), CNR (11.6?±?5.3, 13.2?±?5.6, P?=?0.011), and FOM (19.9?±?23.3, 43.8?±?51.1, P?P?=?0.048) and mean effective dose (10.6?±?5.9 mSv, 8.8?±?5.0 mSv, P?=?0.003) were significantly lower after implementation of ATVS.

Conclusions

Automated tube voltage selection can operator-independently optimize cardiovascular CTA image acquisition parameters with improved image quality at reduced dose.

Key Points

? Automatic tube voltage selection optimizes tube voltage for each individual patient. ? In this population, overall radiation dose decreased while image quality improved. ? This tool may become valuable for improving dose/quality ratio.