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High-b Abdominal FASE-DWI: Phantom and Clinical Studies
Takeshi Yoshikawa1,2, Yoshiharu Ohno1,2, Masao Yui3, Yoshimori Kassai3, Ryuji Shimada4, Katsusuke Kyotani4, and Shinichiro Seki1

1Advanced Biomedical Imaging Research Center, Kobe University Graduate School of Medicine, Kobe, Japan, 2Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan, 3Canon Medical Systems Corporation, Otawara, Japan, 4Kobe University Hospital, Kobe, Japan

Synopsis

Abdominal FASE-DWI at high-b value was evaluated in phantom and clinical studies. Our results showed FASE-DWI can improve image quality and accuracy of ADC, and decrease image distortion.

Introduction & Purpose

Abdominal DWI

  • One of the most important techniques
  • Routinely used worldwide

Remaining problems with single-shot EPI-DWI at 3T

  • Poor image quality and distortion due to air
  • Higher sensitivity to metal deposition or devices

To solve these problems, we developed Fast Advanced Spin Echo (FASE)-DWI (W.I.P.）.

Recently FASE-DWI at high-b value such as 1000 became available.

The purpose of this study was to assess FASE-DWI with high b value in evaluation of abdominal diseases.

MATERIALS and METHODS

Phantom Study

  • 8 bottled phantoms with polyethylene glycol (PEG) diluted with distilled water (concentrations of 10 to 150 mM), water, and fat were, scanned with SE-EPI-DWI (b=0,1000) and FASE-DWI (0,1000) at Vantage Titan 3T (Canon Medical Systems Co.).
  • ADC were calculated and compared.

Clinical Study

Subjects

  • 109 patients (68 men & 41 women, 67.9 years), who were suspected to have malignant tumor in the liver, bile duct (BD), or pancreas, and underwent MR examination at a 3T scanner, were enrolled.
  • 48 patients were diagnosed to have malignant lesions.
  • HCC:28, liver meta:5, CCC: 1, bile duct Ca: 4, panc Ca: 4, pNET: 2, primary colon Ca: 1, LN meta: 2, IPMC: 1
  • 57 malignant lesions were confirmed.
  • HCC: 31, liver meta: 10, CCC: 1, bile duct Ca: 4, panc Ca: 4, pNET: 2, primary colon Ca: 2, LN meta: 2, IPMC: 1

Imaging Technique

  • Vantage Titan 3T (Canon Medical Systems Co.)
  • EPI-DWI TR/TE/FA=6500-7000/70/90, b values: 0 & 1000, matrix: 128 ×128, thickness: 8mm, NEX: 4 scan time: 5:15min, PASTA&SPAIR, PI: 2.5, MPG: (y, z)
  • FASE-DWI (W.I.P.) TR/TE/FA=10000/74/90, b values: 0 & 1000, matrix: 96 ×112, thickness: 8mm, NEX: 6 scan time: 6:39min, SPAIR, PI: 2.5, MPG: (x, y, z)

Quantitative Assessments

  • Abdominal AP and RL diameters were measured for each sequence and each patient.
  • Correlation analyses were performed among EPI-DWI, FASE-DWI, and T2WI.
  • ADCs in malignant lesion and background were measured and compared.
  • Relative ADC differences (rADC = (lesion-background) / (lesion+background)) were calculated and compared.

Qualitative Assessments

  • Amount of abdominal gas and ascites on images was recorded for each patient using a 5-point scale (1:no, 5: massive).
  • Overall image quality and severity of image distortion were visually assessed using a 5-point scale (1:poor/none, 5: excellent/severe) on EPI and FASE, and compared.
  • Regression analyses were done to estimate factors for low image quality and severe distortion.
  • Malignant lesion detection for each patient and conspicuity for each lesion were separately assessed on EPI-DWI and FASE-DWI and compared. ROC analysis was used for lesion detection.

RESULTS

Phantom Study

  • There was no significant difference in phantom ADCs between EPI-DWI and FASE-DWI (Fig. 1).

Abdominal Diameters & Correlations

  • Correlation coefficient was the highest between T2WI and FASE-DWI in both diameters, and was lowest in AP direction with EPI-DWI.

ADCs in Malignant Lesion & Background

  • Lesion ADC was significantly lower than background only on FASE-DWI (Fig. 2).

Malignant Lesion rADC

  • Malignant lesion rADC was significantly higher on FASE-DWI, especially in liver tumors probably due to smaller effects of iron deposition and contrast material (Fig. 3).

Image Quality & Distortion

  • Image quality was slightly better on FASE-DWI.
  • Distortion was significantly severer on EPI-DWI.

Malignant Lesion Conspicuity & Detection

  • There was no significant difference in both (Fig. 4).

The representative case is shown on Fig. 5.

SUMMARY & CONCLUSION

SUMMARY

  • Image quality was slightly better, and distortion was significantly reduced on FASE-DWI.
  • Similar parameters affected image quality and distortion on both.
  • Diagnostic performance for malignant lesions were similar.
  • FASE-DWI may decrease effects of iron deposition and Gd-based contrast medium.
  • Further phantom studies are needed to confirm it.

CONCLUSION

  • FASE-DWI can improve image quality and accuracy of ADC, and decrease image distortion.

Acknowledgements

No acknowledgement found.

References

PREVIOUS REPORTS on extracranial FASE-DWI

  • Ohno Y, et al. EJR 2015 (Lung CA, N-staging)
  • Kito S, et al. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006（head & neck abscesses）

Figures

Figure 1. Results of Phantom Study

Figure 2. ADCs in Malignant Lesion & Background

Figure 3. Malignant Lesion rADC

Figure 4. Malignant Lesion Conspicuity & Detection

Figure 5. HCC Post-op Local Recurrence

Proc. Intl. Soc. Mag. Reson. Med. 27 (2019)
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