In vitro chondrocyte toxicity following long-term, high-dose exposure to Gd-DTPA and a novel cartilage-targeted MR contrast agent

Can gadolinium contrast agents be replaced with saline for direct MR arthrography of the hip? A pilot study with arthroscopic comparison

OBJECTIVE

To compare image quality and diagnostic performance of preoperative direct hip magnetic resonance arthrography (MRA) performed with gadolinium contrast agent and saline solution.

METHODS

IRB-approved retrospective study of 140 age and sex-matched symptomatic patients with femoroacetabular impingement, who either underwent intra-articular injection of 15-20 mL gadopentetate dimeglumine (GBCA), 2.0 mmol/L ("GBCA-MRA" group, n = 70), or 0.9% saline solution ("Saline-MRA" group, n = 70) for preoperative hip MRA and subsequent hip arthroscopy. 1.5 T hip MRA was performed including leg traction. Two readers assessed image quality using a 5-point Likert scale (1-5, excellent-poor), labrum and femoroacetabular cartilage lesions. Arthroscopic diagnosis was used to calculate diagnostic accuracy which was compared between groups with Fisher's exact tests. Image quality was compared with the Mann-Whitney U tests.

RESULTS

Mean age was 33 years ± 9, 21% female patients. Image quality was excellent (GBCA-MRA mean range, 1.1-1.3 vs 1.1-1.2 points for Saline-MRA) and not different between groups (all p > 0.05) except for image contrast which was lower for Saline-MRA group (GBCA-MRA 1.1 ± 0.4 vs Saline-MRA 1.8 ± 0.5; p < 0.001). Accuracy was high for both groups for reader 1/reader 2 for labrum (GBCA-MRA 94%/ 96% versus Saline-MRA 96%/93%; p > 0.999/p = 0.904) and acetabular (GBCA-MRA 86%/ 83% versus Saline-MRA 89%/87%; p = 0.902/p = 0.901) and femoral cartilage lesions (GBCA-MRA 97%/ 99% versus Saline-MRA 97%/97%; both p > 0.999).

CONCLUSION

Diagnostic accuracy and image quality of Saline-MRA and GBCA-MRA is high in assessing chondrolabral lesions underlining the potential role of non-gadolinium-based hip MRA.

KEY POINTS

• Image quality of Saline-MRA and GBCA-MRA was excellent for labrum, acetabular and femoral cartilage, ligamentum teres, and the capsule (all p > 0.18). • The overall image contrast was lower for Saline-MRA (Saline-MRA 1.8 ± 0.5 vs. GBCA-MRA 1.1 ± 0.4; p < 0.001). • Diagnostic accuracy was high for Saline-MRA and GBCA-MRA for labrum (96% vs. 94%; p > 0.999), acetabular cartilage damage (89% vs. 86%; p = 0.902), femoral cartilage damage (97% vs. 97%; p > 0.999), and extensive cartilage damage (97% vs. 93%; p = 0.904).

Editorial Commentary: Gadolinium Intra-Articular Contrast Magnetic Resonance Imaging Is Not Required for Every Patient Undergoing Hip Arthroscopy, but Contrast Magnetic Resonance Imaging Plus Computed Tomography With 3-Dimensional Reconstruction Are Essential for Patients Requiring Revision

For arthroscopic hip surgeons, accurate identification of symptomatic pathology is required. Gadolinium-contrast magnetic resonance arthrography (MRA) is an important imaging option but not necessarily for every patient. Contrast carries some risks, and for patients with acute pathology, effusion may mitigate against the need for contrast. In addition, higher field 3T magnetic resonance imaging shows exceptional detail, comparable sensitivity, and superior specificity to MRA. However, in the revision setting, contrast is indicated to delineate recurrent labral tear versus postsurgical changes, as well as to best show the degree of capsular deficiency. In addition, in the revision setting, computed tomography scan without contrast with 3-dimensional reconstruction also is indicated to evaluate for acetabular dysplasia, surgical over-resection on the acetabular and femoral side, and femoral version. Each patient should be carefully evaluated; MRA with intra-articular contrast is a valuable tool, but not always required.

Hip Magnetic Resonance Arthrography Using Normal Saline Is Less Accurate Than Using a Gadolinium-Based Contrast Agent

PURPOSE

To evaluate the diagnostic performance of hip magnetic resonance (MR) arthrography with a gadolinium-based contrast agent (GBCA) or normal saline (NS) for intra-articular pathologies.

METHODS

This retrospective study was approved by the institutional review board of our hospital, and the requirement for informed consent was waived. The study included 37 consecutive patients (38 hips; 21 right hips; 24 males; mean age, 33 years) who underwent GBCA-hip MR arthrography from July 2011 to January 2020 and 30 consecutive patients (30 hips; 20 right hips; 21 males; mean age, 40 years) who underwent NS-hip MR arthrography from January 2018 to June 2020. All images were evaluated twice independently by two radiologists blinded to the arthroscopic findings for the presence of labral tears, cartilage abnormalities, or ligamentum teres tears. Intrareader and interreader reliabilities were determined by kappa values (k) using the chi-squared test, and diagnostic performance was evaluated based on the arthroscopic findings. A P value less than .05 was considered to indicate statistical significance.

RESULTS

Intra-reader reliability in the detection of intra-articular pathologies ranged from moderate to almost perfect (k = 0.510-0.840) and inter-reader reliability ranged from moderate to substantial (k = 0.441-0.695) for GBCA- and NS-hip MR arthrography. The diagnostic accuracy of GBCA- and NS-hip MR arthrography was as follows: 81.6-92.1% and 66.7-73.3% for labral tears, respectively; 68.4-86.8% and 63.3-70.0% for cartilage abnormality, respectively; and 68.4-76.3% and 50.0-56.7% for ligamentum teres tears, respectively.

CONCLUSION

NS-hip MR arthrography may be less accurate than GBCA-hip MR arthrography. LEVEL OF EVIDENCE: Level II of development of diagnostic criteria (consecutive patients with consistently applied reference standard and blinding).

MR molecular imaging of HCC employing a regulated ferritin gene carried by a modified polycation vector

Purpose: Early diagnosis is essential for reducing liver cancer mortality, and molecular diagnosis by magnetic resonance imaging (MRI) is an emerging and promising technology. The chief aim of the present work is to use the ferritin gene, modified by the alpha-fetoprotein (AFP) promoter, carried by a highly safe vector, to produce signal contrast on T2-weighted MR imaging as an endogenous contrast agent, and to provide a highly specific target for subsequent therapy.

Methods: Polyethyleneimine-β-cyclodextrin (PEI-β-CD, PC) was synthesized as a novel vector. The optimal nitrogen/phosphorus ratio (N/P) of the PC/plasmid DNA complex was determined by gel retardation, biophysical properties and transmission electron microscopy morphological analysis. The transfection efficiency was observed under a fluorescence microscope and analyzed by flow cytometry. Cellular iron accumulation caused by ferritin overexpression was verified by Prussian blue staining, and the resulting contrast imaging effect was examined by MRI.

Results: The modified cationic polymer PC was much safer than high molecular weight PEI, and could condense plasmid DNA at an N/P ratio of 50 with suitable biophysical properties and a high transfection efficiency. Overexpression of ferritin enriched intracellular iron. The short-term iron imbalance initiated by AFP promoter regulation only occurred in hepatoma cells, resulting in signal contrast on MRI. The specific target TfR was also upregulated during this process.

Conclusion: These results illustrate that the regulated ferritin gene carried by PC can be used as an endogenous contrast agent for MRI detection of hepatocellular carcinoma (HCC). This molecular imaging technique may promote safer early diagnosis of HCC, and provide a more highly specific target for future chemotherapy drugs.

Nitroxide radical polymers – a versatile material class for high-tech applications

A comprehensive summary of synthetic strategies for the preparation of nitroxide radical polymer materials and a state-of-the-art perspective on their latest and most exciting applications.