Radiological parameters to predict pancreatic texture: Current evidence and future perspectives

Table 1 Summary of studies evaluating the role of transabdominal ultrasonography in assessing pancreatic texture

Ref.	Number of patients	Aim	Results	Conclusion	Histological correlation
Yashima et al[27], 2012	98	Efficacy of elastography to diagnose chronic pancreatitis	SWV cut off – 1.40 m/s; Sensitivity 75%; Specificity 72%; PPV 69%; NPV 78%	SWV in chronic pancreatitis patients higher than healthy volunteers	Not evaluated
Harada et al[29], 2016	68	Correlation of SWV with pathological degree of fibrosis	SWV cut off – 1.54 m/s; Sensitivity 91%; Specificity 75%; PPV 67%; NPV 93%	SWV significantly correlated with grade of fibrosis and postoperative pancreatic fistula	Good
Llamoza-Torres et al[30], 2016	33	Accuracy of elastography to diagnose chronic pancreatitis	SWV cut off - 1.4 m/s; Sensitivity 58%; Specificity 81%; PPV 76%; NPV 65%	SWV significantly correlated with EUS findings	Not evaluated

SWV: Shear wave velocity; PPV: Positive predictive value; NPV: Negative predictive value; EUS: Endoscopic ultrasonography.

Table 2 Summary of studies evaluating the role of computed tomography abdomen in assessing pancreatic texture

Ref.	Number of patients	PER calculation	Results	Histological correlation
Kang et al[15], 2017	146	1 Equilibrium phase -Pre contrast/ Pre contrast (EP- Pre/Pre); 2 Equilibrium phase -Pre contrast/ Arterial phase - Pre contrast (EP-Pre/AP-Pre)	Mean PER was significantly higher in patients without POPF than in patients with POPF. PER cut off: EP- Pre/Pre -1.10; Pre/AP-Pre - 0.60	Not evaluated
Maehira et al[13], 2019	115	1 Arterial phase/Portal phase (A/P); 2 Portal phase/Late phase (P/L)	Enhancement ratio is significantly higher in POPF group. PER cut off: A/P – 1.19; P/L – 1.17	Not evaluated
Gnanasekaran S et al[32], 2022	61	Equilibrium phase -Pre contrast/ Arterial phase - Pre contrast (EP-Pre/AP-Pre)	PER was significantly higher in patients without POPF than in patients with POPF, PER cut off – 0.673	PER correlated well with fibrosis

PER: Pancreatic enhancement ratio; POPF: Postoperative pancreatic fistula.

Table 3 Summary of studies evaluating the role of magnetic resonance imaging abdomen signal intensity in assessing pancreatic texture

Ref.	Number of patients	Aim	Parameter studied	Results	Conclusion	Histological correlation
Winston et al[34], 1995	89	Correlation of pancreatic SI to predict the presence of pancreatic disease	PLSI	Accuracy -86%; PPV- 88	Pancreatic SI less than that of liver correlates highly with pancreatic disease, especially in younger patients	Not evaluated
Kim et al[16], 2009	43	Accuracy of non-enhanced fat-suppressed T1W MRI in predicting POPF	PLSI, PSSI	PLSI cut off −0.12097 (sensitivity -36%, specificity - 89%); PSSI cut off -0.29979 (sensitivity-79%, specificity-45%)	PLSI, PSSI significantly differed between POPF group and non POPF group, hence, can be useful in predicting POPF	Good
Watanabe et al[36], 2014	29	Efficacy of MRI in assessing degrees of pancreatic fibrosis and predicting POPF	PMSI in unenhanced T1W and T2 W images	Odds ratio of PMSI in T1 W for POPF was 21.3 in patients with an SI ratio of 1.41 and higher	T1W SI ratio and ADC measurements useful to detect advanced pancreatic fibrosis and occurrence of POPF	Good
Noda et al[35], 2016	29	Evaluate the noncontrast-enhanced MRI to grade pancreatic fibrosis and correlate with HbA1c values	PMSI on in- and opposed-phase T1W images	The pancreatic fibrosis grade and HbA1c value were negatively correlated with the SI ratio on opposed-phase T1W images	PMSI could be a potential biomarker for pancreatic fibrosis and elevated HbA1c values	Good
Yoon et al[37], 2016	165	Evaluate the multiparametric pancreatic MRI in the quantification of pancreatic fibrosis and determine relation with POPF	PMSI on in- and opposed-phase T1, IVIM DW imaging; Perfusion fraction (f)	Mean SI ratio for fibrosis; F0 – 1.51; F1 – 1.48; SI ratio cutoff for POPF - 1.40; Odds of developing POPF for a 1% increase in f were 1.17	Multiparametric MR imaging of the pancreas may quantify pancreatic steatosis and fibrosis, and f was significantly associated with POPF	Good
Fukada et al[38], 2022	117	Predictive ability of SI ratio on T1W MRI for POPF after distal pancreatectomy	PMSI on T1W	SI ratio cutoff for POPF - 1.37; Sensitivity- 96.3% Specificity- 52.0%	PMSI is a quantitative biomarker for pancreatic characteristics	Good

T1W: T1 weighted; T2W: T2 Weighted; MRI: Magnetic resonance imaging; POPF: Postoperative pancreatic fistula; PLSI: Pancreas-to-liver signal intensity ratio; PSSI: Pancreas-to-spleen signal intensity ratio; PMSI: Pancreas-to-muscle signal intensity ratio; SI: Signal intensity; IVIM: Intravoxel incoherent motion.

Table 4 Summary of studies evaluating the role of endoscopic ultrasonography strain elastography in assessing pancreatic texture

Ref.	Parameter used	Inference
Machado et al[44], 2012	SH	EUS is useful in differentiating normal pancreas and chronic pancreatitis
Iglesias-Garcia et al[28], 2013	SR	EUS is useful in differentiating normal pancreas and chronic pancreatitis; SR EUS elastography correlated with number of Rosemont criteria ratio
Itoh et al[45], 2014	SH	SH EUS elastography values significantly correlated with fibrosis on histology
Dominguez-Muñoz et al[46], 2015	SR	SR EUS elastography values significantly correlated with exocrine dysfunction
Kim et al[47], 2017	SR	EUS is useful in differentiating normal pancreas and chronic pancreatitis
Kuwahara et al[48], 2017	SH	EUS is useful in differentiating normal pancreas and chronic pancreatitis; SH EUS elastography correlated with number of Rosemont criteria ratio

SR: Strain ratio; SH: Strain histogram; EUS: Endoscopic ultrasonography.