The Impact of TE and TR on Apparent Diffusion Coefficient and Diffusion-derived Vessel Density Quantification: Studies of Healthy Liver and Spleen

Abstract

Purpose

This study investigates the impact of echo time (TE) and repetition time (TR) on apparent diffusion coefficient (ADC) and diffusion-derived vessel density (DDVD) values. Spleen has longer T1 and T2 than the liver, and spleen has a T2 similar to most hepatocellular carcinomas.

Materials and Methods

Liver and spleen diffusion MRI was conducted with six volunteers at 3.0 T with multiple sessions. When TE was changed with steps of TE=46 ms, 52 ms, 60 ms, 70 ms, and 80 ms, TR was fixed at 2000 ms. When TR was changed with steps of TR=200 ms, 300 ms, 500 ms, 1000 ms, and 2000 ms, TE was fixed at 46 ms. The b-values included 0, 1, 2, 10, and 600 s/mm². ADC was calculated with b=0 and b=600 s/mm² images. DDVD was the signal difference between on b=0 image and a very low b-value image (b=1, 2, 10 s/mm²). Thirty-five scans for each ADC data point and 23 scans for each DDVD data point were included.

Results

Following the increase in TE from 46ms to 80ms, the ADC value increased by 23.9% (median) for the liver and 18.2% (median) for the spleen, while the ADC_spleen/ADC_liver ratio was smaller when TE was longer. Following the increase in TR from 200ms to 2000 ms, the ADC value decreased by 4.8% (median) for the liver and 14.6% (median) for the spleen, while the ADC_spleen/ADC_liver ratio was smaller when TR was longer. Following the increase in TE from 46ms to 80ms, there was a decrease in the DDVD value. DDVD_spleen/DDVD_liver ratios were greater when TE was long. Following the increase in TR from 200ms to 2000ms, there was a biphasic change in the DDVD value. The DDVD values were highest when TR was 500ms, and DDVD_spleen/DDVD_liver ratios followed a mono-phasic decrease.

Conclusion

TR and TE have very notable impact on the ADC and DDVD values of the liver and spleen.

Key Points

• An increase of TE and an increase of TR are both associated with a decreasing ADC_spleen/ADC_liver ratio.

• Longer TE is associated with an increased DDVD_spleen/DDVD_liver ratio.

• The lesion detectability and lesion-to-tissue contrast by ADC and DDVD maps may be amplified by optimizing TE and TR values.

Citation Format

• Xu FY, Wáng YXJ. The Impact of TE and TR on Apparent Diffusion Coefficient and Diffusion-derived Vessel Density Quantification: Studies of Healthy Liver and Spleen. Rofo 2026; DOI 10.1055/a-2777-6695

Zusammenfassung

Ziel

Diese Studie untersucht den Einfluss von TR und TE auf den ADC und die diffusionsabgeleitete Gefäßdichte (DDVD). Die Milz hat längere T1- und T2-Zeiten als die Leber, und die Milz weist eine ähnliche T2-Zeit wie die meisten hepatozellulären Karzinome auf.

Materialien und Methoden

Eine Diffusions-MRT von Leber und Milz wurde mit 6 Freiwilligen bei 3,0 T in mehreren Sitzungen durchgeführt. Bei Änderung der TE in Schritten von TE=46 ms, 52 ms, 60 ms, 70 ms und 80 ms wurde TR auf 2000 ms fixiert. Bei Änderung von TR in Schritten von TR=200 ms, 300 ms, 500 ms, 1000 ms und 2000 ms wurde TE auf 46 ms fixiert. Die b-Werte umfassten 0, 1, 2, 10, 600 s/mm². ADC wurde mit Bildern mit b=0 und b=600 s/mm² berechnet. DDVD war die Signaldifferenz zwischen einem Bild mit b=0 und einem Bild mit sehr niedrigem b-Wert (b=1, 2, 10 s/mm²). 35 Scans für jeden ADC-Datenpunkt und 23 Scans für jeden DDVD-Datenpunkt wurden einbezogen.

Ergebnisse

Nach Erhöhung der Echozeit (TE) von 46 ms auf 80 ms stieg der ADC-Wert in der Leber um 23,9 % (Median) und in der Milz um 18,2 % (Median). Das Verhältnis ADC_Milz/ADC_Leber war bei längerer TE geringer. Nach Erhöhung der Repetitionszeit (TR) von 200 ms auf 2000 ms sank der ADC-Wert in der Leber um 4,8 % (Median) und in der Milz um 14,6 % (Median). Auch hier war das Verhältnis ADC_Milz/ADC_Leber bei längerer TR geringer. Nach der Erhöhung des TE-Werts von 46 ms auf 80 ms sank der DDVD-Wert. Die DDVD_Milz/DDVD_Leber-Verhältnisse waren bei längerer TE höher. Nach der Erhöhung des TR von 200 ms auf 2000 ms kam es zu einer zweiphasigen Veränderung des DDVD-Wertes; die DDVD-Werte waren am höchsten, als der TR 500 ms betrug, und die DDVD_Milz/DDVD_Leber-Verhältnisse folgten einem einphasigen Rückgang.

Schlussfolgerung

TR und TE haben einen sehr deutlichen Einfluss auf die ADC- und DDVD-Werte von Leber und Milz.

Kernaussagen

• Ein Anstieg von TE und TR sind beide mit einem sinkenden ADC_Milz/ADC_Leber-Verhältnis verbunden.

• Eine längere TE ist mit einem erhöhten DDVD_Milz/DDVD_Leber-Verhältnis verbunden.

• Die Läsionserkennbarkeit und der Läsions-Gewebe-Kontrast durch ADC- und DDVD-Karten können durch Optimierung der TE- und TR-Werte verbessert werden.

Keywords

Diffusion weighted imaging - spleen - Liver

Introduction

Diffusion-weighted imaging (DWI) plays a pivotal role in MRI evaluations for a variety of pathologies, and the apparent diffusion coefficient (ADC) is the most commonly used quantitative metric. Many reports have studied the impact of diffusion gradient b-value selection on ADC quantification. However, only recently have studies focused on the impact of TE during data acquisition on IVIM parameters [perfusion fraction (PF), D_slow, D_fast], although the theory of intravoxel incoherent motion (IVIM) was first published in 1996. For the liver and the pancreas, a longer echo time (TE) is associated with a higher PF value and a lower D_slow [1] [2] [3] [4]. A wide range of TE and TR (repetition time) values have been used for ADC calculation ([Fig. 1]). Nevertheless, few reports have studied the impact of TE and TR on ADC values. In a gel phantom study (T1=1273 ms, T2=315 ms, 1.5 T scanner), Celik et al. [5] reported that when TE changed from 68 to 200 ms, an increase in ADC value was detected. Fourteen different TR values ranging from 1000 to 17000 ms were also tested, and the ADC value was higher for TR values shorter than 3000 ms. Additionally, there was no difference in the ADC values measured for TR values longer than 3000 ms. In another gel phantom study (T1= 2431~3039 ms, T2=60~172 ms), Ogura et al. [6] reported that when TE changed from 50 to 400 ms (50, 100, 200, 300 400 ms, 1.5T scanner), no difference was seen in the ADC value at TE = 50 or 100 ms, but the ADC value decreased with further increases in TE. When TR varied from 1000 to 8000 ms, no difference in ADC value was detected [6]. With a triple-modality 3D abdominal phantom and 1.5T scanner, Aldarrab et al. [7] reported a decrease in liver ADC value when TE increased from 75 to 85 ms and an increase in liver ADC value when TR increased from 1000 to 4000 ms. Using a 3.0 T scanner, Higaki et al. [8] tested TRs of 1850 and 6000 ms for prostate tissues and noted no difference in ADC results of these two TR values. These studies’ results are therefore conflicting.

Fig. 1 TE and TR values used for ADC calculation in literature. The data in this graph represents a random selection of 30 reports (refer to supplementary document). Blue dot in A represents an intravoxel incoherent motion study.

Our study aimed to systematically investigate the impact of clinically relevant TE and TR on ADC values for the liver and spleen. As the liver and spleen have markedly different T2 values (approximately, liver T2: 40 ms; spleen T2: 60 ms; liver T1: 800 ms; spleen T1: 1300 ms, 3.0 T data) [9], we studied how the impacts of TE and TR on liver and spleen might be moderated by tissue T2. Spleen has a T2 similar to most of the hepatocellular carcinoma (i.e. around 60 ms at 3T) [10] but with a perfusion similar to that of the liver [9]. Another emerging DWI metric is diffusion-derived vessel density (DDVD), which has been shown to be useful in practice to evaluate liver hemangioma [11], liver focal nodular hyperplasia [10], and placenta in preeclampsia and placenta accreta spectrum patients, etc. Clarifying how TE and TR affect DDVD values will provide useful information for future valuations regarding the usefulness and the interpretation of DDVD values in different normal tissues and pathologies.

Materials and Methods

The liver and spleen DWI data acquisition was conducted with young healthy volunteers (three males aged between 26–32 years, three females aged between 28–30 years). The study was approved by the institutional ethical committee, and informed consent was obtained from all participants. MRI scans were performed between February and May 2025.

The DWI scan utilized a single-shot spin-echo echo-planar sequence with a 3.0 T magnet (Ingenia Elition X, Philips Healthcare, Best, Netherlands). Fat suppression was achieved using the SPAIR technique (Spectral Attenuated Inversion Recovery). Scan parameters included slice thickness of 5 mm, slice gap of 1 mm, acquisition matrix of 64×56, field of view of 350 × 350 mm, NEX=1, and slice number of 20. When TE was considered as a variable and changed with steps of TE=46 ms, 52 ms, 60 ms, 70 ms, 80 ms, TR was fixed at 2000 ms. When TR was considered as a variable and changed with steps of TR=200 ms, 300 ms, 500 ms, 1000 ms, and 2000 ms, TR was fixed at 46 ms. The b-values included 0, 1, 2, 10, and 600 s/mm². During the scan, the study participants were instructed to have shallow free breathing. Multiple scan sessions were acquired.

Liver and spleen ADC and DDVD values were measured with MATLAB (MathWorks, Natick, MA, USA), based on regions of interest (ROI) approach. ROI was placed manually on the DWI image to cover a large portion of liver and spleen parenchyma while avoiding large vessels.

ADC was calculated according to the following formula:

ADC = ln(S(b₁ )/S(b₂ )) /(b₂ − b₁ ) Eq. (1)

where b₂ and b₁ refer to b=600 and b=0 s/mm², respectively, and S(b₁ ) and S(b₂ ) denote the image signal intensity acquired at the b-value of b=0 and b=600 s/mm², respectively.

The DDVD-weighted image was calculated according to the following formula:

DDVD_b2 = S(b₀)/ROIarea0 – S(b₂)/ROIarea2 [unit: arbitrary unit (a.u.)/pixel] Eq.(2)

where ROIarea0 and ROIarea2 refer to the number of pixels in the selected region-of-interest (ROI) on b=0 and b=2 s/mm² DW image, respectively. S(b₀) refers to the measured sum signal intensity within the ROI when b=0, and S(b₂) refers to the measured sum signal intensity within the ROI when b=2 s/mm². Thus Sb/ROIarea equates to the mean signal intensity within the ROI. S(b₂) and ROIarea2 were further replaced with b=1 and b=10 s/mm² DW image, resulting in DDVD_b1 and DDVD_b10.

For all analyses, we considered the average of all slice measurements included as the examination value, and the final step involved weighting based on the percentage ROI area for each slice. For all acquired MRI data, images with notable motion and artifact were discarded, finally 35 scans were available for each ADC calculation, and 23 scans were available for each DDVD calculation (Supplementary Table 1).

Results

Following the increase in TE from 46 to 80 ms, ADC values increased, both for the liver and for the spleen ([Fig. 2]). ADC values increased by a median of 23.9% for the liver and a median of 18.2% for the spleen. The ADC_spleen/ADC_liver ratio showed a decrease following an increase in TE (median decrease of 5.6%, [Table 1]).

Fig. 2 Changes in ADC values (in box-and-whiskers plot) following the increase in TE from 46 to 80 ms (A–C) and in TR from 200 to 2000 ms (D–F). A p<0.0001 (Kruskal-Wallis test); B p=0.025 (Kruskal-Wallis test); C p=0.068 (Pearson correlation); D p=0.175 (Pearson correlation); E p=0.0396 (Kruskal-Wallis test); F p=0.176 (Pearson correlation); Y-axis for A, B, D, and E × 10^–3 mm²/s. X-axis: TE or TR in ms.

Table 1 ADC and DDVD values for the shorter TE/TR and longer TE/TR, and the percentage difference (Δ value). Unit of ADC: × 10^–3 mm²/s. Unit of DDVD: a.u./pixel. TE/TR: milliseconds.

Organs	Metrics	MRI scan parameters, TR and TE
Liver		TR=2000 ms		TE=46 ms
		TE=46 ms	TE=80 ms	TR=200 ms	TR=500 ms	TR=2000 ms
	ADC	1.478	1.828	1.553	–	1.478
	ΔADC	–	23.7%	–	–	–4.83% for TR=200 –> 2000
	DDVDb1	104.4	61.0	75.9	180.9	104.4
	ΔDDVDb1	–	–41.6%	–	138.4% for TR=200 –>500	–42.3% for TR=500–>2000
	DDVDb2	112.0	69.6	70.5	178.550	112.0
	ΔDDVDb2	–	–37.9%	–	153.3% for TR=200 –>500	–37.3% for TR=500–>2000
	DDVDb10	145.1	88.4	104.1	210.6	145.1
	ΔDDVDb10	–	–39.1%	–	102.3% for TR=200 –>500	–31.1% for TR=500–>2000
Spleen	ADC	0.994	1.175	1.190	–	1.016
	ΔADC	–	18.2%	–	–	–14.6%
	DDVDb1	120.1	94.2	110.7	319.3	120.1
	ΔDDVDb1	–	–21.6%	–	188.4% for TR=200 –>500	–62.4% for TR=500 –> 2000
	DDVDb2	115.3	95.6	116.6	269.2	138.8
	ΔDDVDb2	–	–17%	–	130.9% for TR=200 –>500	–48.4% for TR=500 –> 2000
	DDVDb10	126.1	107.0	113.6	312.5	126.1
	ΔDDVDb10	–	–15.1%	–	175.1% for TR=200 –> 500	–59.6% for TR=500 –> 2000
Spleen/Liver	ADC	0.707	0.667	0.755	–	0.707
	ΔADC	–	–5.61%	–	–	–6.36% for TR=200 –> 2000
	DDVDb1	1.07	1.368	1.457	–	1.070
	ΔDDVDb1	–	27.8%	–	–	–26.6% for TR=200 –> 2000
	DDVDb2	0.994	1.217	1.508	–	0.994
	ΔDDVDb2	–	22.5%	–	–	–34.1% for TR=200 –> 2000
	DDVDb10	0.869	1.105	1.338	–	0.869
	ΔDDVDb10	–	27.2%	–	–	–35.1% for TR=200 –> 2000

Following the increase in TR from 200 to 2000 ms, ADC values decreased, both for the liver and for the spleen ([Fig. 2]). ADC values decreased by a median of 4.8% for the liver and a median of 14.6% for the spleen. The ADC_spleen/ADC_liver ratio showed a decrease following an increase in TR (median decrease of 6.4%, [Table 1]).

Following the increase in TE from 46 to 80 ms, DDVD values decreased, including all DDVD_b1, DDVD_b2, and DDVD_b10 values, both for the liver and for the spleen ([Fig. 3]). The extent of value decreases was greater for the liver than for the spleen. Thus the DDVD_spleen/DDVD_liver ratio was greater when TE was longer ([Table 1]).

Fig. 3 Changes in DDVD values (in box-and-whiskers plot) following the increase in TE from 46 to 80 ms (liver: A, D, G; spleen: B, E, H), and the DDVD_spleen/DDVD_liver ratio (C, F, I). A p<0.0001; B p=0.0792; C p=0.122; D p<0.0001; E p=0.079 (Pearson correlation); F p=0.082 (Pearson correlation). G p<0.0001; H p=0.0845 comparing TE=46 ms vs. TE=80 ms (Mann Whitney test); I p=0.071; all by Kruskal-Wallis test except E, F, and H. Y-axis for A, B, D, E a.u./pixel. X-axis: TE ms.

Following the increase in TR from 200 to 2000 ms, there was a biphasic change in DDVD values, including all DDVD_b1, DDVD_b2, and DDVD_b10 values, both for the liver and for the spleen. DDVD values were highest when TR was 500 ms, and DDVD values were lowest for TR at 200 ms. Liver DDVD values were the same for TR of 1000 and 2000 ms, while spleen DDVD was lower when TR was 2000 ms compared to 1000 ms. The DDVD_spleen/DDVD_liver ratio followed a monophasic decrease after TR was increased.

When TR was 2000 ms and TE was 46 ms, the ratio of DDVD_spleen /DDVD_liver was 1.07, 0.994, and 0.867, respectively, for the DDVD_b1, DDVD_b2, and DDVD_b10 ratios.

Discussion

[Fig. 2] suggests that as TE increases liver and spleen ADC values also increase. From the perspective of measuring MRI signal strength, a longer TE is practically equivalent to a shorter “apparent” (i.e. observed) T2. The ADC value is determined by the difference in signal strength between the low b-value image and the high b-value image. A longer “effective” TE (which is longer than the nominal TE), or a shorter “measured” T2, will allow a faster signal decay between these two images, which in turn results in a higher ADC value [1] [12]. As the liver has a shorter T2 than the spleen, this TE dependance is more apparent for the liver than for the spleen. As a result, when TE is longer, the ADC_spleen/ADC_liver ratio was measured lower. We may hypothesize that when TE is longer, the ADC of liver cancers (which mostly have a longer T2 than liver parenchyma) will be measured even lower relative to the liver. The impact of TR on liver and spleen ADC values is the opposite of TE. A shorter TR was associated with a decrease in liver and spleen ADC values. This is likely due to the fact that a shorter TR does not allow the magnetization in the axial plane to sufficiently recover in the longitudinal plane. For this reason, the percentage ADC change between TRs of 200 and 2000 ms was bigger for the spleen than for the liver. With a TR of 2000 ms as reference, a shorter TR will elevate spleen ADC values compared to liver ADC values (and so would be for liver cancers with a longer T2). Shorter TR is implemented when the scan speed needs to be very fast. [Fig. 2] shows that the ADC_spleen/ADC_liver ratio deviated more from “1” when TE is long and/or TR is long; it is possible that ADC_HCC would demonstrate an even lower value when long TE and/or long TR are applied for DWI data acquisition.

[Fig. 3] suggests that as TE increased liver DDVD and spleen DDVD decreased. DDVD value is determined by the difference in signal strength between the b=0 image and the nonzero low b-value image (1, 2, or 10 s/mm² in this study); therefore, a longer TE, or a shorter “measured” T2, will decrease the signal strength difference between these two images. As the liver has a shorter T2 than the spleen, this TE dependance of DDVD is more apparent for the liver than for the spleen (this pattern is the same as ADC). Therefore, when TE is longer, spleen DDVD was measured higher relative to the liver. When TE is longer, DDVD value of liver cancers (which mostly have a richer perfusion and a longer T2) would be measured even higher relative to the liver. Thought with limited data, it was indeed empirically observed that the ratio of DDVD_HCC/DDVD_liver measured higher when TE was 84 ms than when TE was 59 ms [10]. Therefore, DDVD tissue contrast may be improved between HCC and liver parenchyma by using a longer TE.

The impact of TR on DDVD values of the liver and spleen, as shown in [Fig. 4], was unexpected. DDVD measured highest when TR was 500 ms, but lower when TR was shorter (such as 200 ms) and moderately long (such as 2000 ms). Currently, we cannot offer a satisfactory explanation for this phenomenon. The ratio of DDVD_spleen/DDVD_liver showed a monophasic pattern, with shorter TR associated with a higher ratio. Accordingly, tentative results have shown that a shorter TR measured a higher DDVD_HCC/DDVD_liver ratio [10] [13].

Fig. 4 Changes in DDVD values (in box-and-whiskers plot) following the increase in TR from 200 to 2000 ms (liver: A, D, G; spleen: B, E, H), and the DDVD_spleen/DDVD_liver ratio (C, F, I). A p<0.0001 (TR=200~500 ms) and p<0.0001 (TR=500~2000 ms); B p<0.0001 (TR=200~500 ms) and p<0.0001 (TR=500~2000 ms); C p<0.025 (TR=300~2000 ms); D p<0.0001 (TR=200~500 ms) and p<0.0001 (TR=500~2000 ms); E p=0.0021 (TR=200 ~500 ms) and p=0.0002 (TR=500~2000 ms); F p=0.0089 (TR =200~2000 ms); G p<0.0001 (TR=200~500 ms) and p=0.0004 (TR=500 ~2000 ms); H p<0.0001 (TR=200~500 ms) and p<0.0001 (TR=500~2000 ms); I p=0.0019; all by Kruskal-Wallis test. Y-axis for A, B, D, E, G and H a.u./pixel. X-axis: TR in ms.

It is known that the blood flow speed is slightly faster in the spleen than in the liver, and blood pool volume is slightly higher in the liver than in the spleen. Thus the perfusion between the liver and the spleen is very similar. In the current study, when TR was 2000 ms and TE was 46 ms, the ratios of DDVD_spleen /DDVD_liver were 1.07, 0.994, and 0.867, respectively, for DDVD_b1, DDVD_b2, and DDVD_b10. This is consistent with an earlier study (n=26 healthy volunteers) at 1.5 T with TR of 1600 ms and TE of 63 ms, where DDVD_b1, DDVD_b2, and DDVD_b10 had DDVD_spleen/DDVD_liver ratios of 1.053, 0.935, 0.830, respectively [9]. This suggests the comparability between different magnetic strengths and between scanners at least in relative terms. DDVD measurement is more closely related to physiological measurements when TR is long or modestly long, TE is short, and the 2^nd b-value is very low [9] [13] [14]. When a TE of 59 ms (TR=1600 ms) and b=0, 2 mm²/s value were applied to 26 cases of HCC (hepatocellular carcinoma), a mean DDVD_HCC/DDVD_liver ratio of 1.42 was measured [13]. This is consistent with the ratio of perfusion CT-measured blood volume of HCC to blood volume of liver of 1.38 [13].

In one study, Yao et al. [15] used the DDVD ratio to evaluate 24 pleomorphic adenomas (PA), 14 malignant tumors, and 16 Warthin’s tumors. DDVDr was DDVD of the tumor divided by DDVD of tumor free parotid gland tissue. A systematic literature search was conducted for parotid gland tumor perfusion imaging and histology microvessel density studies. Perfusion parameters of PAs, malignant tumors, and Warthin’s tumors were further normalized by PA measurement. The ratio results of malignant tumor DDVD and Warthin’s tumors DDVD were compared with study results in the literature. It was noted that DDVDr ratios of both malignant tumor to PA (1.56) and Warthin’s tumor to PA (2.47) were very similar to the mean ratio of CT-measured blood volume of these tumors (1.54 for malignant tumor to PA, and 2.51 for Warthin’s tumor to PA). The DDVDr ratio of malignant tumor to PA was also approximately close to a histology microvessel density ratio report (1.29), and DDVDr ratio of Warthin’s tumor to PA was close to the medium value of histology microvessel density ratio (2.41) of three reports [15]. It should be noted, during the interpretation of ADC maps and DDVD maps, it is the relative ratio which is more useful in practice. For example, a liver lesion is considered as “low ADC or high ADC” or “low DDVD or high DDVD” compared to the adjacent liver parenchyma, and spleen parenchyma is also often used as the reference tissue.

There are a number of limitations to this study. The number of volunteers was limited. When TR was short (such as 200 ms), the noise level was high. To increase the signal strength and shorten the scan duration, we applied a low matrix size, which led to a large pixel size and low resolution. Short TR may be relevant for accelerated DWI, and signal may be compensated by artificial intelligence powered accelerated data reconstruction in the future. Our results appear to agree with the ADC phantom results reported by Celik et al. [5], but they cannot be reconciled with the phantom results reported by Ogura et al. [6] and Aldarrab et al. [7].

In conclusion, this study demonstrates TE and TR have very notable impacts on ADC values of the liver and spleen. More importantly, liver and spleen, having their similar perfusion statuses but different T1 and T2 relaxations, respond in different magnitudes for their respective ADC values following the TE/TR changes. These are the same for DDVD. Since a liver lesion is considered as “low ADC or high ADC” or “low DDVD or high DDVD” compared to the adjacent liver parenchyma, and spleen parenchyma is also often used as the reference tissue, the results of this study have practical relevance. The lesion detectability and lesion-to-tissue contrast on ADC and DDVD maps may be amplified by optimizing TE and TR values.

Clinical Relevance

• Following the increase in TE from 46 to 80 ms, the ADC value increases by 23.9% (median) for the liver and 18.2% (median) for the spleen. The ADC_spleen/ADC_liver ratio is lower when TE is longer.

• Following the increase in TR from 200 to 2000 ms, the ADC value decreases by 4.8% (median) for the liver and 14.6% (median) for the spleen. The ADC_spleen/ADC_liver ratio is lower when TR is longer.

• Following the increase in TE from 46 to 80 ms, there is a decrease in DDVD value for the liver and the spleen, while the DDVD_spleen/DDVD_liver ratio increases.

• The DDVD value is highest when TR is 500 ms. However, DDVD_spleen/DDVD_liver ratios follow a monophasic decrease after increasing TR from 200 to 2000 ms.

Data availability statement

The data that supports the findings of this study are available from the corresponding author upon reasonable request.

Conflict of Interest

Yì Xiáng J. Wáng is the founder of Yingran Medicals Ltd., which develops medical image-based diagnostics software. Fan-Yi Xu declares no conflict of interest.

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Publication History

Received: 25 October 2025

Accepted after revision: 19 December 2025

Article published online:
20 January 2026