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Unicompartmental knee arthroplasty MRI: impact of slice-encoding for metal artefact correction MRI on image quality, findings and therapy decision


Agten, Christoph A; Del Grande, Filippo; Fucentese, Sandro F; Blatter, Samuel; Pfirrmann, Christian W A; Sutter, Reto (2015). Unicompartmental knee arthroplasty MRI: impact of slice-encoding for metal artefact correction MRI on image quality, findings and therapy decision. European Radiology, 25(7):2184-2193.

Abstract

OBJECTIVES To evaluate the impact of slice-encoding for metal artefact correction (SEMAC) on image quality, findings, and therapy decision in patients with unicompartmental knee arthroplasty (UKA). METHODS Forty-five painful UKAs were examined at 1.5T-MRI (STIR, proton-density(PD)-weighted sequence, each with SEMAC and high-bandwidth). Artefact size, image quality, anatomic depiction, and clinically relevant findings were compared between SEMAC and high-bandwidth (2 readers). In 30 patients, therapy decision was retrospectively assessed by two orthopaedic surgeons without MRI, with high-bandwidth-MRI, and with SEMAC-MRI. RESULTS SEMAC reduced mean artefact size for STIR (11.8 cm(2) vs. 37.7 cm(2)) and PD (16.8 cm(2) vs. 18.9 cm(2)), p < 0.0005 for both comparisons. SEMAC showed more blurring than high-bandwidth, p < 0.0005. STIR-SEMAC revealed more bone marrow oedema (29 vs. 18 patients, p = 0.001, 30 vs. 13 patients, p < 0.0005, for reader 1 and 2 respectively). PD-SEMAC was worse in detecting meniscal lesions (6 missed, p = 0.031, 9 missed, p = 0.004, by reader 1 and 2 respectively) than PD-high-bandwidth. Revision-surgery was chosen in 12 and 11 patients without MRI (surgeon 1 and 2), with high-bandwidth-MRI in 15 and 14 patients, and with SEMAC-MRI in 19 and 14 patients. CONCLUSIONS STIR-SEMAC was useful in detecting bone marrow oedema and influenced the orthopaedic surgeons' decisions towards surgery, while PD-SEMAC showed no clinical benefit. KEY POINTS • Slice-encoding for metal artefact correction (SEMAC) MRI reduces metal-induced artefact size. • STIR SEMAC detects more bone marrow oedema in painful unicompartmental knee arthroplasty. • STIR SEMAC can help the orthopaedic surgeon with decision making. • PD SEMAC suffers from blurring of images, potentially masking relevant meniscal lesions. • PD SEMAC does not improve cartilage lesion detection in the non-operated compartments.

Abstract

OBJECTIVES To evaluate the impact of slice-encoding for metal artefact correction (SEMAC) on image quality, findings, and therapy decision in patients with unicompartmental knee arthroplasty (UKA). METHODS Forty-five painful UKAs were examined at 1.5T-MRI (STIR, proton-density(PD)-weighted sequence, each with SEMAC and high-bandwidth). Artefact size, image quality, anatomic depiction, and clinically relevant findings were compared between SEMAC and high-bandwidth (2 readers). In 30 patients, therapy decision was retrospectively assessed by two orthopaedic surgeons without MRI, with high-bandwidth-MRI, and with SEMAC-MRI. RESULTS SEMAC reduced mean artefact size for STIR (11.8 cm(2) vs. 37.7 cm(2)) and PD (16.8 cm(2) vs. 18.9 cm(2)), p < 0.0005 for both comparisons. SEMAC showed more blurring than high-bandwidth, p < 0.0005. STIR-SEMAC revealed more bone marrow oedema (29 vs. 18 patients, p = 0.001, 30 vs. 13 patients, p < 0.0005, for reader 1 and 2 respectively). PD-SEMAC was worse in detecting meniscal lesions (6 missed, p = 0.031, 9 missed, p = 0.004, by reader 1 and 2 respectively) than PD-high-bandwidth. Revision-surgery was chosen in 12 and 11 patients without MRI (surgeon 1 and 2), with high-bandwidth-MRI in 15 and 14 patients, and with SEMAC-MRI in 19 and 14 patients. CONCLUSIONS STIR-SEMAC was useful in detecting bone marrow oedema and influenced the orthopaedic surgeons' decisions towards surgery, while PD-SEMAC showed no clinical benefit. KEY POINTS • Slice-encoding for metal artefact correction (SEMAC) MRI reduces metal-induced artefact size. • STIR SEMAC detects more bone marrow oedema in painful unicompartmental knee arthroplasty. • STIR SEMAC can help the orthopaedic surgeon with decision making. • PD SEMAC suffers from blurring of images, potentially masking relevant meniscal lesions. • PD SEMAC does not improve cartilage lesion detection in the non-operated compartments.

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4 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Balgrist University Hospital, Swiss Spinal Cord Injury Center
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:28 January 2015
Deposited On:01 Apr 2015 15:34
Last Modified:05 Apr 2016 19:12
Publisher:Springer
ISSN:0938-7994
Publisher DOI:https://doi.org/10.1007/s00330-015-3596-4
PubMed ID:25627351

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