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Letters to the Editor |
Department of Radiology, Hacettepe University, Billur Sok 43/10, GOP, Ankara, Turkey 06700 e-mail: borapeynir{at}gmail.com
We read with great interest the article by Dr Fürst and colleagues (1) in the April 2007 issue of Radiology. Stem cell administration into the portal venous circulation in an effort to augment preoperative gain in future liver remnant volume (FLRV) is really interesting. However, we have concerns about the Materials and Methods and the volumetry results of this study.
The ileocolic cannulation with open laparotomy was used in three patients of group II in order to prevent an access pathway through a large hepatic tumor mass and/or an injury to the future liver remnant. As far as the literature with larger series of experience is concerned, a transhepatic ipsilateral approach with intravenous sedation and local anesthesia does not necessarily result in injury to the FLRV (2).
Furthermore, according to the tables given in the article, tumor volumes do not appear to be taken into consideration in calculation of "preoperative relative left lateral liver volume" in some patients (patients 1, 4, and 5 in group I and patients 4 and 6 in group II) (1). In patient 3 of the first group and patients 1, 2, 3, 5, and 7 of the second group, actual tumor volumes are not given throughout the article. However, we see that the tumor volumes appeared to be excluded during the volumetric calculations. In patient 6 of the first group, tumor volume is given in the text and is excluded properly from calculations. Moreover, in a previously published article by these authors (3) in the journal Stem Cells, the authors reported their first three patients who also seem to be the first three subjects of the current article (1). In looking at the numbers given in the tables of the same patients in both studies, there are some inconsistencies that need to be clarified and recalculated. Although "characteristics of processed bone marrow" and "patient characteristics" are almost identical for patient 1 (except for the patient age: 46 vs 47 years) in these two studies, liver volumetry is now calculated completely differently. In table 1 of the Radiology article (1), the relative gain of FLRV for patient 1 is given as 37.7% (should be 61.1% according to the given data), but this was given as 50.9% in the previous article (3). Similar age inconsistency exists for patient 2 in the same table, but the rest of the given data for patients 2 and 3 are consistent with those in the previous study. Additionally, in table 2, relative gain of FLRV for patient 7 is calculated as 34.6% but should be 39.3% according to the data given in the Radiology article (1) and according to the well-described formula by Tsuda et al (4).
In conclusion, although the findings of this study are very valuable for the stem cell literature, the data inconsistencies emphasized above need to be clarified, which may also affect the statistical comparisons.
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,
L. Benjamin Fritz, MD, DMD, MBA *,
Erhard Godehardt, PhD 
,
Ulrich Mödder, MD *, and
Wolfram T. Knoefel, MD
* Institute of Diagnostic Radiology,, Heinrich-Heine-University of Duesseldorf, Moorenstr 5, 40225 Duesseldorf, Germany e-mail: fuerst{at}med.uni-duesseldorf.de
Department of General Surgery,, Heinrich-Heine-University of Duesseldorf, Moorenstr 5, 40225 Duesseldorf, Germany
Department of Cardiothoracic Surgery, Heinrich-Heine-University of Duesseldorf, Moorenstr 5, 40225 Duesseldorf, Germany
Ileocolic portal access.—In three patients of group II, ileocolic cannulation was used to prevent an access pathway through a right hepatic tumor mass. Alternatively, a percutaneous left transhepatic approach would have been possible. As this access route is occasionally associated with a risk of injury of the left lateral liver, we preferred the ileocolic approach.
Tumor volume and relative left lateral liver volume.—In all patients, tumor volumes were considered for calculation of percentage FLRV according to the formula: FLRV/(TLV – TU), where TLV is total liver volume and TU is tumor volume. In patient 1 (group I), tumor volume was 50 mL. Accordingly, the percentage FLRV was 18.3% (ie, 427/[2378 – 50]). In patient 6 (group I) percentage FLRV was 19% (ie, 217/[1317 – 177]). As it is necessary to consider only intrahepatic tumor masses for calculating percentage FLRV, a tumor volume of 0 mL was considered in patient 5 (group I) and patient 4 (group II). These patients had cholangiocellular carcinoma with no intrahepatic tumor definable at computed tomography. Similarly, small intrahepatic tumor masses (<10 mL) were considered in two patients with small nodular metastases of colorectal carcinomas (patient 4 in group I and patient 6 in group II).
Previous stem cell study.—The first three patients in our current article (1) are identical to the three stem cell patients in our previously published article (2). The Stem Cell article was cited, accordingly (see reference 21 of our Radiology article).
For publication in Radiology, all volumetric data were reevaluated. This explains minor differences compared with the previous data, particularly in stem cell patient 1. In the previous article in Stem Cell, preoperative FLRVs have been calculated differently, considering only FLRV and total liver volume, TLV, according to the formula: FLRV = FLRV/TLV. However, differences resulting from reevaluation did not have a decisive impact on volume gains or on patient inclusion in the study, as preoperative FLRVs were below the inclusion threshold of 25% in both studies.
Miscalculation of relative gain in FLRV.—Unfortunately, a miscalculation of relative gain in FLRV ([absolute gain in FLRV/FLRV before portal vein embolization]·100) occurred in patient 1 (group I) and in patient 7 (group II).
We thank Dr Ozkan and colleagues for pointing out this miscalculation and we apologize for this mistake. The relative gain in FLRV in patient 1 (group I) is not 37.7% but 61.1% (261 divided by 427 in table 1) and the relative gain in patient 7 is not 34.6% but 39.4% (102 divided by 259 in table 2). However, after correction of this miscalculation, the effect of stem cell application indicated by our data appears even more pronounced. Thus, the mean relative gain in FLRV after portal vein embolization should be 81.2% ± 34.3 (standard deviation) in group I and 39.8% ± 20.3 in group II (P = .021), rather than the values of 77.3% ± 38.2 (group I) and 39.1% ± 20.4 (group II) (P = .039) that were given in the published data. An erratum follows at the end of this section.
Once again, we regret this calculation mistake; however, through correction we see a supportive rather than a negative impact on the main conclusion of the study.
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