## 4 Discussion
This study's methodology was limited, and it lacked comparison of 3 DPLMs and 2D axial/multiplanar imaging, but it supported the idea that 3 DPLMs may be superfluous for qualified surgeons [9; 19]. 3 DPLMs' value may be limited, therefore, to particularly complex LCR cases, where lesions are located deeply among intrahepatic structures, or where underlying liver disease limits future liver remnant viability [9; 13; 17; 19; 31; 40]. HPB surgeons must be proficient in correlating mental reconstructions of patient liver anatomy with the actual surgical field during an operation [19]. This is particularly important during laparoscopic procedures where there is restricted anatomical overview [12; 17]. Several articles argue, therefore, of the benefits of 3 DPLMs for intraoperative guidance during LCR [9; 13; 19; 22; 33; 40]. 3 DPLMs can be oriented and compared directly to the surgical field, improving comprehension and navigation of the viewed anatomy (Figure 3) [9; 19; 33]. In this application, 3 DPLMs can be used to better locate and identify lesions for resection [9; 13; 19], verify the position of vascular structures to inform potential adjustments to the resection plane [19; 33], and better comprehend the locations of deeper anatomical structures hidden within the liver parenchyma [13; 19; 22]. 3 DPLMs may also improve intraoperative detection of smaller metastases to ensure removal [13], and they may decrease the likelihood of intraoperative complications such as damage to intrahepatic vessels [19] and liver devascularisation [13; 40]. Again, these findings are not generalisable as they are drawn primarily from qualitative, case-report evidence. A prospective comparative study by [PERSON] et al. [19] was the only original research identified that demonstrates direct evidence of 3 DPLMs' intraoperative utility during LCR. In this study, the use of 3 DPLMs for intraoperative guidance resulted in real-time changes to the surgical strategy for four patients in the 3 DPLM group  
Figure 3: Comparison of 3 DPLM to the surgical field shows that it enhances identification of key structures. vB5: the ventral bile duct of segment 5, dB5: the dorsal bile duct of segment 5, B8: the bile duct of segment 8, RAB: right anterior bile duct, RHV: right hepatic vein, RHV-V5: the venous reflux of hepatic segment 5 to RHV, RHV-V6: the venous reflux of hepatic segment 6 to RHV. Reprinted with permission under the open access from [PERSON] et al. [19]. (16.7% of the study group) due to improved navigation of the surgical field (vs. no changes in the non-3 DPLM group). This study was limited by its small sample size and heterogeneity of patient cases. The impact of 3 DPLMs on intraoperative decision making in this study could also have been confounded by its surgeons using indocyanine green fluorescent staining as a supplementary navigation tool across the entire study population. Elsewhere, as with surgical planning, 3 DPLMs' utility for intraoperative guidance of LCR was demonstrated qualitatively and through case-report evidence, but currently lacks a methodologically rigorous backing. Similarly, it seems intraoperative use of 3 DPLMs is likely mostly relevant for highly complex or laparoscopic cases [9; 13; 19]. Despite the reported preoperative and intraoperative value of 3 DPLMs for LCR, this review identified no statistically significant evidence that 3 DPLMs improve patients' surgical outcomes. Only three studies included in this review recorded patients' intra- and/or postoperative outcome data [19; 30; 33]. There were no statistically significant positive correlations identified between the use of 3 DPLMs and patients' future liver remnant volume, duration of surgery, intraoperative blood loss, resection margins, cancer reoccurrence, liver devascularisation, or postoperative liver failure. The lack of statistical evidence does not disprove the potential benefit of 3 DPLMs for patient outcomes.