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The effects of voxel localization and time of echo on the diagnostic accuracy of cystic brain tumors in 3 tesla magnetic resonance spectroscopy.

Rezvanizadeh A, Firouznia K, Salehi-Sadaghiani M, Mohseni M, Gharaei D, Ghanaati H, Saligheh Rad H, Masoudnia M - Iran J Radiol (2012)

Bottom Line: There was no statistically significant difference among the compared TEs.The percentages of ratios above the cut-off point at all TEs were more in the rim compared to the center and in the union of both compared to the rim or center.If not accessible, the use of the union of peripheral and central voxels enhances the sensitivity when compared to usage of peripheral or central voxels solely.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran.

ABSTRACT

Background: Although magnetic resonance spectroscopy (MRS) has been shown as an effective diagnostic tool in distinguishing inflammation from neoplasm in cystic brain lesions, the optimum approach in selecting the portions of lesions in MRS and the possible effects of different times of echoes (TEs) remains unknown.

Objectives: To determine the most effective TE in diagnosing neoplastic lesions based on detecting choline (Cho), N acetyl aspartate (NAA) and creatinine (Cr). Moreover, the role of voxel localization on the diagnosis of the neoplastic nature of the lesions is assessed through comparing the abovementioned metabolite ratios in the rim and center of each lesion with the same TE.

Patients and methods: In 16 patients with brain cystic tumors, MRS was performed at TEs of 30, 135 and 270 ms for detection of Cho, NAA and Cr metabolites using a 3 tesla MRI unit. The percentage of analyzed ratios greater than a cut-off point of 1.3 for Cho/Cr and 1.6 for Cho/NAA were calculated.

Results: Cho/Cr and Cho/NAA ratio means at all TEs were more at the central area in comparison with the periphery, although none of the differences were statistically significant. There was no statistically significant difference among the compared TEs. The percentages of ratios above the cut-off point at all TEs were more in the rim compared to the center and in the union of both compared to the rim or center. All the patients had at least one voxel with a Cho/Cr ratio of more than 1.3 when the voxel was chosen according to the hotspots shown in the chemical shift imaging map, regardless of their location at all examined TEs.

Conclusions: Selection of voxels with the guide of chemical shift imaging map yields to 100% diagnostic sensitivity. If not accessible, the use of the union of peripheral and central voxels enhances the sensitivity when compared to usage of peripheral or central voxels solely.

No MeSH data available.


Related in: MedlinePlus

Comparing the percentage of patients with a metabolite ratio higher than a cut-off point of 1.3 for Cho/Cr ratios and 1.6 for Cho/NAA ratios and their relation to the voxel location. Any triple bar group corresponds to a specific ratio-TE which are tagged under the bars. The color of each bar indicates the location of assessment (rim vs. center vs. union of them). Values with * differ significantly (0.01 < P < 0.05).
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fig940: Comparing the percentage of patients with a metabolite ratio higher than a cut-off point of 1.3 for Cho/Cr ratios and 1.6 for Cho/NAA ratios and their relation to the voxel location. Any triple bar group corresponds to a specific ratio-TE which are tagged under the bars. The color of each bar indicates the location of assessment (rim vs. center vs. union of them). Values with * differ significantly (0.01 < P < 0.05).

Mentions: In addition, the percentage of analyzed ratios greater than a cut-off point of 1.3 for Cho/Cr ratio and 1.6 for Cho/NAA ratio were calculated for all ratios at different TEs and locations (Figure 3). At TE = 30, 87.5% of Cho/Cr ratios at the peripheral area were above the cut-off point, while this percentage decreased to 62.5% at the central portion and the union of these two places resulted in 93.75% above the cut-off point. The percentages greater than the cut-off point, for Cho/NAA ratio at TE = 30 were 62.5% and 43.75% for the rim and center, respectively. Considering the two ratios together, the percentage increased to 75%. At TE = 135, 87.5% of Cho/Cr ratios at the peripheral area and 75% at the central area exceeded the cut-off point. The union of the rim and center leaded to 93.75% of the ratios above the cut-off point. For Cho/NAA ratio at TE = 135, the percentages of ratios which exceeded the cut-off point were 68.75%, 62.5% and 87.5% for the rim, center and their union, respectively. The resultant percentages of Cho/Cr ratios at TE = 270 above the defined threshold for the peripheral and central area and their union were 93.75%, 87.5% and 93.75%, respectively. For Cho/NAA ratio at TE = 270 the calculated percentages of ratios above the cut-off point were 81.25%, 81.25% and 93.75% in the order mentioned previously. In a same trend for all applied TEs, the percentages of ratios above the cut-off point were more in union of the center and the periphery. In addition, the peripheral area showed greater numbers compared with the central ratios. Cochran’s Q test was used to assess the differences between percentages of the ratios above the cut-off point in the rim, center or union of both. As it is depicted in Figure 3, there was a statistically significant difference in the Cho/Cr ratio of the center and union of the central and peripheral area, revealing a statistically significant difference (P < 0.05) at TE = 30. Finally, all the patients had at least one voxel with a Cho/Cr ratio of more than 1.3, when the voxel was chosen according to the hotspots shown in the chemical shift imaging map of Cho/Cr ratios, regardless of their location in the center or rim at all examined TEs.


The effects of voxel localization and time of echo on the diagnostic accuracy of cystic brain tumors in 3 tesla magnetic resonance spectroscopy.

Rezvanizadeh A, Firouznia K, Salehi-Sadaghiani M, Mohseni M, Gharaei D, Ghanaati H, Saligheh Rad H, Masoudnia M - Iran J Radiol (2012)

Comparing the percentage of patients with a metabolite ratio higher than a cut-off point of 1.3 for Cho/Cr ratios and 1.6 for Cho/NAA ratios and their relation to the voxel location. Any triple bar group corresponds to a specific ratio-TE which are tagged under the bars. The color of each bar indicates the location of assessment (rim vs. center vs. union of them). Values with * differ significantly (0.01 < P < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3569551&req=5

fig940: Comparing the percentage of patients with a metabolite ratio higher than a cut-off point of 1.3 for Cho/Cr ratios and 1.6 for Cho/NAA ratios and their relation to the voxel location. Any triple bar group corresponds to a specific ratio-TE which are tagged under the bars. The color of each bar indicates the location of assessment (rim vs. center vs. union of them). Values with * differ significantly (0.01 < P < 0.05).
Mentions: In addition, the percentage of analyzed ratios greater than a cut-off point of 1.3 for Cho/Cr ratio and 1.6 for Cho/NAA ratio were calculated for all ratios at different TEs and locations (Figure 3). At TE = 30, 87.5% of Cho/Cr ratios at the peripheral area were above the cut-off point, while this percentage decreased to 62.5% at the central portion and the union of these two places resulted in 93.75% above the cut-off point. The percentages greater than the cut-off point, for Cho/NAA ratio at TE = 30 were 62.5% and 43.75% for the rim and center, respectively. Considering the two ratios together, the percentage increased to 75%. At TE = 135, 87.5% of Cho/Cr ratios at the peripheral area and 75% at the central area exceeded the cut-off point. The union of the rim and center leaded to 93.75% of the ratios above the cut-off point. For Cho/NAA ratio at TE = 135, the percentages of ratios which exceeded the cut-off point were 68.75%, 62.5% and 87.5% for the rim, center and their union, respectively. The resultant percentages of Cho/Cr ratios at TE = 270 above the defined threshold for the peripheral and central area and their union were 93.75%, 87.5% and 93.75%, respectively. For Cho/NAA ratio at TE = 270 the calculated percentages of ratios above the cut-off point were 81.25%, 81.25% and 93.75% in the order mentioned previously. In a same trend for all applied TEs, the percentages of ratios above the cut-off point were more in union of the center and the periphery. In addition, the peripheral area showed greater numbers compared with the central ratios. Cochran’s Q test was used to assess the differences between percentages of the ratios above the cut-off point in the rim, center or union of both. As it is depicted in Figure 3, there was a statistically significant difference in the Cho/Cr ratio of the center and union of the central and peripheral area, revealing a statistically significant difference (P < 0.05) at TE = 30. Finally, all the patients had at least one voxel with a Cho/Cr ratio of more than 1.3, when the voxel was chosen according to the hotspots shown in the chemical shift imaging map of Cho/Cr ratios, regardless of their location in the center or rim at all examined TEs.

Bottom Line: There was no statistically significant difference among the compared TEs.The percentages of ratios above the cut-off point at all TEs were more in the rim compared to the center and in the union of both compared to the rim or center.If not accessible, the use of the union of peripheral and central voxels enhances the sensitivity when compared to usage of peripheral or central voxels solely.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran.

ABSTRACT

Background: Although magnetic resonance spectroscopy (MRS) has been shown as an effective diagnostic tool in distinguishing inflammation from neoplasm in cystic brain lesions, the optimum approach in selecting the portions of lesions in MRS and the possible effects of different times of echoes (TEs) remains unknown.

Objectives: To determine the most effective TE in diagnosing neoplastic lesions based on detecting choline (Cho), N acetyl aspartate (NAA) and creatinine (Cr). Moreover, the role of voxel localization on the diagnosis of the neoplastic nature of the lesions is assessed through comparing the abovementioned metabolite ratios in the rim and center of each lesion with the same TE.

Patients and methods: In 16 patients with brain cystic tumors, MRS was performed at TEs of 30, 135 and 270 ms for detection of Cho, NAA and Cr metabolites using a 3 tesla MRI unit. The percentage of analyzed ratios greater than a cut-off point of 1.3 for Cho/Cr and 1.6 for Cho/NAA were calculated.

Results: Cho/Cr and Cho/NAA ratio means at all TEs were more at the central area in comparison with the periphery, although none of the differences were statistically significant. There was no statistically significant difference among the compared TEs. The percentages of ratios above the cut-off point at all TEs were more in the rim compared to the center and in the union of both compared to the rim or center. All the patients had at least one voxel with a Cho/Cr ratio of more than 1.3 when the voxel was chosen according to the hotspots shown in the chemical shift imaging map, regardless of their location at all examined TEs.

Conclusions: Selection of voxels with the guide of chemical shift imaging map yields to 100% diagnostic sensitivity. If not accessible, the use of the union of peripheral and central voxels enhances the sensitivity when compared to usage of peripheral or central voxels solely.

No MeSH data available.


Related in: MedlinePlus