Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL): Application with fast spin-echo imaging

Background and Purpose Multi-parametric MRI of the entire spine is technologist-dependent, time consuming, and often limited by inhomogeneous fat suppression. We tested a technique to provide rapid automated total spine MRI screening with improved tissue contrast through optimized fat-water separation. Methods The entire spine was auto-imaged in two contiguous 35 cm field of view (FOV) sagittal stations, utilizing out-of-phase fast gradient echo (FGRE) and T1 and/or T2 weighted fast spin echo (FSE) IDEAL (Iterative Decomposition of Water and Fat with Echo Asymmetric and Least-squares Estimation) sequences. 18 subjects were studied, one twice at 3.0T (pre and post contrast) and one at both 1.5 T and 3.0T for a total of 20 spine examinations (8 at 1.5 T and 12 at 3.0T). Images were independently evaluated by two neuroradiologists and run through Automated Spine Survey Iterative Scan Technique (ASSIST) analysis software for automated vertebral numbering. Results In all 20 total spine studies, neuroradiologist and computer ASSIST labeling were concordant. In all cases, IDEAL provided uniform fat and water separation throughout the entire 70 cm FOV imaged. Two subjects demonstrated breast metastases and one had a large presumptive schwannoma. 14 subjects demonstrated degenerative disc disease with associated Modic Type I or II changes at one or more levels. FGRE ASSIST afforded subminute submillimeter in-plane resolution of the entire spine with high contrast between discs and vertebrae at both 1.5 and 3.0T. Marrow signal abnormalities could be particularly well characterized with IDEAL derived images and parametric maps. Conclusion IDEAL ASSIST is a promising MRI technique affording a rapid automated high resolution, high contrast survey of the entire spine with optimized tissue characterization.

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Effect of laterality, gender, age and body mass index on the fat fraction of salivary glands in healthy volunteers: assessed using iterative decomposition of water and fat with echo asymmetry and least-squares estimation method

Dentomaxillofacial Radiology ◽

10.1259/dmfr.20180263 ◽

2019 ◽

Vol 48 (3) ◽

pp. 20180263 ◽

Cited By ~ 3

Author(s):

Guo-Yi Su ◽

Chuan-Bing Wang ◽

Hao Hu ◽

Jun Liu ◽

Hong-Yuan Ding ◽

...

Keyword(s):

Body Mass Index ◽

Healthy Volunteers ◽

Least Squares ◽

Salivary Glands ◽

Body Mass ◽

Estimation Method ◽

Least Squares Estimation ◽

Iterative Decomposition ◽

Fat Fraction ◽

Decomposition Of Water

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Assessment of bone marrow fat fractions in the mandibular condyle head using the iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL-IQ) method

PLoS ONE ◽

10.1371/journal.pone.0246596 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0246596

Author(s):

Kug Jin Jeon ◽

Chena Lee ◽

Yoon Joo Choi ◽

Sang-Sun Han

Keyword(s):

Bone Marrow ◽

Least Squares ◽

Temporomandibular Joint ◽

Mandibular Condyle ◽

Least Squares Estimation ◽

Control Group ◽

Dixon Method ◽

Iterative Decomposition ◽

Iq Method ◽

Decomposition Of Water

The prevalence of temporomandibular joint disorder (TMD) is gradually increasing, and magnetic resonance imaging (MRI) is becoming increasingly common as a modality used to diagnose TMD. Edema and osteonecrosis in the bone marrow of the mandibular condyle have been considered to be precursors of osteoarthritis, but these changes are not evaluated accurately and quantitatively on routine MRI. The iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL-IQ) method, as a cutting-edge MRI technique, can separate fat and water using three asymmetric echo times and the three-point Dixon method. The purpose of this study was to analyze the quantitative fat fraction (FF) in the mandibular condyle head using the IDEAL-IQ method. Seventy-nine people who underwent MRI using IDEAL-IQ were investigated and divided into 1) the control group, without TMD symptoms, and 2) the TMD group, with unilateral temporomandibular joint (TMJ) pain. In both groups, the FF of the condyle head in the TMJ was analyzed by two oral and maxillofacial radiologists. In the TMD group, 29 people underwent cone-beam computed tomography (CBCT) and the presence or absence of bony changes in the condylar head was evaluated. The FF measurements of the condyle head using IDEAL-IQ showed excellent inter-observer and intra-observer agreement. The average FF of the TMD group was significantly lower than that of the control group (p < 0.05). In the TMD group, the average FF values of joints with pain and joints with bony changes were significantly lower than those of joints without pain or bony changes, respectively (p < 0.05). The FF using IDEAL-IQ in the TMJ can be helpful for the quantitative diagnosis of TMD.

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