Not All Green Is Tophi: The Importance of Optimizing Minimum Attenuation and Using a Tin Filter to Minimize Clumpy Artifacts on Foot and Ankle Dual-Energy CT

Park, Eun Hae; Yoo, Wan‐Hee; Song, You Seon; Byon, Jung Hee; Pak, Jongjun; Choi, Yun‐Jung

doi:10.2214/ajr.19.22222

Cited by 24 publications

(25 citation statements)

References 34 publications

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“…DECT revealed 57 colour-coded DECT lesions characterized by a high mean DECT ratio (1.24, SD 0.17) consistent with lesions representing calcified tissues (possibly calcifications in the menisci/cartilage and/or CPP crystal depositions) visualization of MSU depositions, but lowering of HU threshold also resulted in an increased amount of artefacts, especially artefacts in well-known locations such as tendons, nail-beds and skin [20]. One of the studies found that the artefacts lead to misclassifications of patients [21], whereas the other study found specificity of DECT examination to remain unchanged [20].…”

Section: Discussionmentioning

confidence: 99%

“…In our study, we did not assess the effect of altering neither the DECT ratio cut-off nor the HU threshold, as the aim of our study was to evaluate colour-coded DECT lesions using factory default gout settings. However, two recent studies have investigated the effect of changing postprocessing protocols when performing DECT examinations [20,21]. Both studies investigated the effect of lowering the threshold of attenuation from 150 HU to 120 HU [20] or 130 HU [21], respectively.…”

Section: Discussionmentioning

confidence: 99%

“…However, two recent studies have investigated the effect of changing postprocessing protocols when performing DECT examinations [20,21]. Both studies investigated the effect of lowering the threshold of attenuation from 150 HU to 120 HU [20] or 130 HU [21], respectively. Both studies found this to result in an improved A 54-year-old gout patient with no comorbidities.…”

Section: Discussionmentioning

confidence: 99%

“…However, two recent studies have investigated the effect of changing postprocessing protocols when performing DECT examinations [ 20 , 21 ]. Both studies investigated the effect of lowering the threshold of attenuation from 150 HU to 120 HU [ 20 ] or 130 HU [ 21 ], respectively. Both studies found this to result in an improved visualization of MSU depositions, but lowering of HU threshold also resulted in an increased amount of artefacts, especially artefacts in well-known locations such as tendons, nail-beds and skin [ 20 ].…”

Section: Discussionmentioning

confidence: 99%

“…Both studies found this to result in an improved visualization of MSU depositions, but lowering of HU threshold also resulted in an increased amount of artefacts, especially artefacts in well-known locations such as tendons, nail-beds and skin [ 20 ]. One of the studies found that the artefacts lead to misclassifications of patients [ 21 ], whereas the other study found specificity of DECT examination to remain unchanged [ 20 ].…”

Section: Discussionmentioning

confidence: 99%

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Dual-energy CT in gout patients: Do all colour-coded lesions actually represent monosodium urate crystals?

et al. 2020

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Background Dual-energy CT (DECT) can acknowledge differences in tissue compositions and can colour-code tissues with specific features including monosodium urate (MSU) crystals. However, when evaluating gout patients, DECT frequently colour-codes material not truly representing MSU crystals and this might lead to misinterpretations. The characteristics of and variations in properties of colour-coded DECT lesions in gout patients have not yet been systematically investigated. The objective of this study was to evaluate the properties and locations of colour-coded DECT lesions in gout patients. Methods DECT of the hands, knees and feet were performed in patients with suspected gout using factory default gout settings, and colour-coded DECT lesions were registered. For each lesion, properties [mean density (mean of Hounsfield Units (HU) at 80 kV and Sn150kV), mean DECT ratio and size] and location were determined. Subgroup analysis was performed post hoc evaluating differences in locations of lesions when divided into definite MSU depositions and possibly other lesions. Results In total, 4033 lesions were registered in 27 patients (23 gout patients, 3918 lesions; 4 non-gout patients, 115 lesions). In gout patients, lesions had a median density of 160.6 HU and median size of 6 voxels, and DECT ratios showed an approximated normal distribution (mean 1.06, SD 0.10), but with a right heavy tail consistent with the presence of smaller amounts of high effective atomic number lesions (e.g. calcium-containing lesions). The most common locations of lesions were 1st metatarsophalangeal (MTP1), knee and midtarsal joints along with quadriceps and patella tendons. Subgroup analyses showed that definite MSU depositions (large volume, low DECT ratio, high density) had a similar distribution pattern, whereas possible calcium-containing material (high DECT ratio) and non-gout MSU-imitating lesions (properties as definite MSU depositions in non-gout patients) were primarily found in some larger joints (knee, midtarsal and talocrural) and tendons (Achilles and quadriceps). MTP1 joints and patella tendons showed only definite MSU depositions. Conclusion Colour-coded DECT lesions in gout patients showed heterogeneity in properties and distribution. MTP1 joints and patella tendons exclusively showed definite MSU depositions. Hence, a sole focus on these regions in the evaluation of gout patients may improve the specificity of DECT scans.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…However, two recent studies have investigated the effect of changing postprocessing protocols when performing DECT examinations [ 20 , 21 ]. Both studies investigated the effect of lowering the threshold of attenuation from 150 HU to 120 HU [ 20 ] or 130 HU [ 21 ], respectively. Both studies found this to result in an improved visualization of MSU depositions, but lowering of HU threshold also resulted in an increased amount of artefacts, especially artefacts in well-known locations such as tendons, nail-beds and skin [ 20 ].…”

Section: Discussionmentioning

confidence: 99%