Diffusion weighted magnetic resonance imaging of liver: Principles, clinical applications and recent updates

Table 1 Comparison of SSEPI diffusion-weighted magnetic resonance imaging vs conventional magnetic resonance sequences for detection of hepatic metastases[15,20-22,27]

Ref.	b value(s/mm2)	Compared with (Seq)	Sensitivity of DWI vs other sequences	Accuracy of DWI vs other sequences	Advantages of DWI
Bruegel et al[27]	50, 300, 600	5 different T2-TSE (Turbo Spin Echo) sequences	0.88-0.91 compared to 0.45-0.62	0.91-0.92 compared to 0.47-0.67	Better sensitivity and accuracy
Zech et al[21]	50	Fat suppressed T2WI	83% vs 61%	-	Better image quality
					Fewer artifacts
					Better sensitivity
Hardie et al[15]	0, 50, 500	Gadolinium enhanced T1WI	66.3% vs 73.5%	88.2% and 88.2% for DW-MRI, 90.2% and 92.2% for CE MRI, respectively, for observers 1 and 2	Not significantly different
Donati et al[20]	0, 150, 500	Combined (Gd-EOB-DTPA) enhanced MRI/DWI vs Gd-EOB-DTPA enhanced MRI and DWI alone	-	Gd- EOB-DTPA/DWI: 0.84 and 0.83 vs 0.73 and 0.72 for DWI alone	Increase in diagnostic confidence
					No significant increase in diagnostic accuracy
Colagranade et al[22]	0-500	Added value of DWI for lesion detection in unenhanced and Gd-EOB-DTPA enhanced MRI	-62.5% for unenhanced MRI w/o DWI	-81.1% for unenhanced MRI w/o DWI	DWI improved all statistical parameters in the unenhanced examinations, as for nodules either smaller or greater than 1 cm. In EOB-enhanced examinations DWI increased specificity/negative predictive value
			-85.0% for unenhanced MRI+ DWI	-89% for unenhanced MRI + DWI
			-95.6% for CE MRI	-92.9% for CEMRI
			-97.3% for CE MRI + DWI	-95.5% for CE MRI + DWI

DWI: Diffusion-weighted imaging; MRI: Magnetic resonance imaging.

Table 2 Liver lesion characterization based on ADC values[33,35,44,45,102]

Ref.	Lesion type	Mean ADC (10-3mm2/s)	Sample size	b-values	Conclusion
Parsai et al[44]	Cyst	2.66	2	100, 200, 500, 750, and 1000 mm2/s	ADC cutoff value threshold of 1.6 × 10-3 mm2/s yielded higher accuracy for differentiating benign from malignant lesions. DWI is not reliable to differentiate malignant from benign solid lesions
	HCC	1.07	26
	Metastases	1.04	39
Taouli et al[98]	Cyst	3.63	52	0, 500	Threshold ADC value of 1.5 × 10-3 mm2/s to differentiate between benign and malignant lesions, but with a significant overlap between benign hepatocellular lesions and HCCs
	HCC	1.33
	Metastases	0.94
Parikh et al[35]	Cyst	2.54	211	0, 50, 500	Accuracy of 75.3% for differentiating benign from malignant, by using a threshold ADC of less than 1.60 × 10-3mm2/s . Equivalent performance of DW imaging and T2- weighted imaging for lesion characterization
	HCC	1.31
	Metastases	1.5
Bruegel et al[33]	Cyst	3.02	204	50, 300, 600	88% of lesions were correctly classified as benign or malignant using a threshold value of 1.63 × 10-3 mm2/s. Measurements of the ADCs of focal liver lesions on the basis of a respiratory triggered DW-SS-EPI sequence may constitute a useful supplementary method for lesion characterization
	HCC	1.05
	Metastases	1.22
Gourtsoyianni et al[102]	Cyst	2.55	37	0, 50, 500, 1000	Sensitivity and specificity of 100% for differentiating benign from malignant lesions using a cutoff ADC value of 1.47 × 10-3 mm2/s
	HCC	1.38
	Metastases	0.99

HCC: Hepatocellular carcinoma; DWI: Diffusion-weighted imaging.

Table 3 Role of diffusion-weighted magnetic resonance in assessment of treatment response[75-79]

Ref.	Treatment modality	Tumor type	DW-MR parameter evaluated	Study results/teaching point
Chapiro et al[79]	TACE	HCC	(3D) quantitative enhancement-based and DW volumetric MR	High accuracy and intermethod agreement of 3D quantitative techniques in the assessment of tumor necrosis after TACE is clinically relevant
				High diagnostic performance of qEASL criteria and qADC may help in triaging patients for repeat treatment after a TACE session
Mannelli et al[87]	TACE	HCC	ADC measured with DWI in treatment response	Pre TACE ADC obtained at 0, 50, 500 s/mm2b values before and after treatment may be used to predict HCC response to TACE
Park et al[42]	Radiotherapy	HCC	DW MR vs conventional MR for treatment response	Improved detection of viable tumor when DW MR is added to conventional sequences
Yu et al[76]	Radiation therapy	HCC	DW MR	Change in ADC value before and after RT is related to local progression free survival. Hence ADC value and RECIST may substitute for mRECIST in patients who cannot receive contrast agents
Schraml et al[77]	Radiofrequency	n = 16 HCC, 1 = cholangiocarcinoma, and 37 = metastases (28 colorectal cancer, 3 melanoma, 3 breast cancer, 1 pancreatic cancer, 1 gastric cancer, esophageal cancer)	DW MR and mean ADC values	ADC-based evaluation of signal alterations adjacent to the ablation zone may contribute to the identification of local tumor progression and nontumoral post- treatment tissue changes
	Ablation

HCC: Hepatocellular carcinoma; DW MR: Diffusion-weighted magnetic resonance; TACE: Trans-arterial chemoembolization.