Quantitative index calculated by99mTc-GSA scintigraphy

Morikatsu Yoshida, Shinya Shiraishi, Noriko Tsuda, Fumi Sakamoto, Seiji Tomiguchi, Yasuyuki Yamashita

1Department of Diagnostic Radiology, Graduate School of Life Sciences,2Department of Diagnostic Medical Imaging, School of Health Faculty of Life Sciences, Kumamoto University, Honjo, Kumamoto, Japan

Correspondence to: Morikatsu Yoshida, PhD. Department of Diagnostic Radiology Kumamoto University, 1-1-1 Chuo-Ku, Honjo, Kumamoto, Japan. Email: mo-yoshi@kumamoto-u.ac.jp.

Quantitative index calculated by99mTc-GSA scintigraphy

Morikatsu Yoshida1, Shinya Shiraishi1, Noriko Tsuda1, Fumi Sakamoto1, Seiji Tomiguchi2, Yasuyuki Yamashita1

1Department of Diagnostic Radiology, Graduate School of Life Sciences,2Department of Diagnostic Medical Imaging, School of Health Faculty of Life Sciences, Kumamoto University, Honjo, Kumamoto, Japan

Correspondence to: Morikatsu Yoshida, PhD. Department of Diagnostic Radiology Kumamoto University, 1-1-1 Chuo-Ku, Honjo, Kumamoto, Japan. Email: mo-yoshi@kumamoto-u.ac.jp.

99mTc-galactosyl human serum albumin (GSA) scintigraphy is useful to evaluate hepatic function and hepatic functional reserve. A reliable SPECT and CT integrated system is now commercially available. Using this system, we can obtain99mTc-GSA SPECT/CT fused imaging with a small registration error. Therefore, the99mTc-GSA scintigraphy techniques prove more useful in clinical practice than have been previously reported. In the latest Annals of Surgical Oncology on Oct 2014, the uptake index (UI) values calculated from99mTc-GSA scintigraphy are reported to be useful for predicting the functional reserve of the future remnant liver. In this paper, we describe the usefulness of99mTc-GSA scintigraphy as well as some cautions that are necessary as regards using the system.

99mTc-GSA scintigraphy; SPECT/CT; uptake index (UI)

View this article at:http://dx.doi.org/10.3978/j.issn.1000-9604.2014.12.12necessary to know the strong and weak points associated with the images for accurate and adequate use.

The receptor index (LHL15) and clearance index (HH15) are the most commonly used parameters and are reported to be useful for assessing the function and functional reserve of the liver. Although both indices are very simple and convenient, from our own experience, we suggest there are some cautions that are warranted in relation to using both indices. The first, the anatomical information is not suffcient to adequately evaluate the function of the future remnant liver. Also, to evaluate the regional function these indices have to be corresponded with the CT volumetry. The second, it is not possible to correct the attenuation. Attenuation is the most important factor affecting the quantitative imaging (5). The third, the tumor location sometimes resulted in underestimating the whole liver function. Because the dynamic scintigrams are obtained by a frontal gamma camera, when a big tumor is located on the anterior section or lateral section of liver, the counts for the whole liver are sometimes underestimated. The UI and UI values are also obtained by dynamic scintigrams. UI and UI values warrant the same cautions as those for HH15 and LHL15. Therefore, for the proper use of UI, we have to understand these cautions.

A SPECT and CT integrated system is now commercially available. This SPECT/CT integrated system allows us to obtain SPECT/CT fused images with an excellent registration. The excellent registration of SPECT/CT fused imaging is a very important factor. First of all, we can perform CT based attenuation correction on the reconstructed SPECT image. The liver is not round and the area around the liver is quite complex. Therefore, CT based attenuation correction is better than Chang’s methods and it results in preserving the good quantitative nature of the indices. Secondly, we can add the anatomical information to the SPECT image. Although the SPECT image contains 3D information, this is not sufficient to evaluate the regional function corresponding with the surgical procedure. Moreover, the latest SPECT/CT integrated systems have multi-detector row CT. In our hospital, the SPECT/CT system has 16 row-CT. Using this system, we can make fused imaging of the SPECT image and dynamic CE-CT image. In this way, we can evaluate the function of regional liver based on the portal and hepatic vein tributaries (6). UI values are calculated by a combination of UI and99mTc-GSA SPECT/CT fused images. However, it was not clarifed what kind of machines and methods were used to obtain99mTc-GSA SPECT image and CT image. So it is diffcult to understand how to reduce the registration error of99mTc-GSA SPECT/CT fused images.

Moreover, we should know that there are other cautions needed due to the pharmacokinetics of GSA. GSA binds to asialoglycoprotein receptors on the hepatocyte cell membranes and is excreted into the bile. Usually the excretion started in about 40 minutes after the administration of GSA. Therefore, SPECT scanning should be finished at least within 40 minutes to obtain accurate information of the functional distribution of the liver. We perform dynamic scintigrams and SPECT scanning in one test and obtain the SPECT images within 35 minutes. Although UI values were obtained by the combination of UI and99mTc-GSA SPECT/CT fused images, the SPECT parameter was not fully explained. Therefore, we question the quantitative accuracy of the UI values due to the scant information provided about image acquisition and reconstruction.

Conclusions

In this report, we suggested that the indices calculated from99mTc-GSA scintigraphy are useful for safe hepatectomy. Especially, the UI values are ideal for hepatectomy planning. On the other hand, for the accurate assessment of regional hepatic function we have clarified the strong and weak points of99mTc-GSA scintigraphy and the pharmacokinetics of GSA.

Acknowledgements

Disclosure: The authors declare no confict of interest.

1. Hoekstra LT, de Graaf W, Nibourg GA, et al. Physiological and biochemical basis of clinical liver function tests: a review. Ann Surg 2013;257:27-36.

2. Mao Y, Du S, Ba J, et al. Using Dynamic 99mT c-GSA SPECT/CT Fusion Images for Hepatectomy Planning and Postoperative Liver Failure Prediction. Ann Surg Oncol 2014. [Epub ahead of print].

3. Du S, Mao Y, Tong J, et al. A novel liver function evaluation system using radiopharmacokinetic modeling of technetium-99m-DTPA-galactosyl human serum albumin. Nucl Med Commun 2013;34:893-9.

4. Yumoto Y, Yagi T, Sato S, et al. Preoperative estimation of remnant hepatic function using fusion images obtainedby (99m)Tc-labelled galactosyl-human serum albumin liver scintigraphy and computed tomography. Br J Surg 2010;97:934-44.

5. Shiraishi S, Tomiguchi S, Utsunomiya D, et al. AJR Am J Roentgenol 2006;186:1450-7.

6. Yoshida M, Shiraishi S, Sakamoto F, et al. Assessment of hepatic functional regeneration after hepatectomy using (99m)Tc-GSA SPECT/CT fused imaging. Ann Nucl Med 2014;28:780-8.

Cite this article as:Yoshida M, Shiraishi S, Tsuda N, Sakamoto F, Tomiguchi S, Yamashita Y. Quantitative index calculated by99mTc-GSA scintigraphy. Chin J Cancer Res 2014;26(6):641-643. doi: 10.3978/j.issn.1000-9604.2014.12.12

Endoscopic techniques in gastroenterology have been developing rapidly over the past two decades. Advances in minimally invasive endoscopic techniques allow for the detection and treatment of more gastrointestinal (GI) diseases than ever. In a manner of speaking, the advent of miniature ultrasound device coupled with endoscopy further shapes up a new epoch of intraluminal exploration. Today, endoscopic ultrasound (EUS) detection is indicated for study of a wider-ranging conditions within the GI wall, and even going beyond the latter, applicable to the organs surrounding the GI tract (1), including the lung, pancreas, gallbladder, liver, adrenal glands, bladder, and uterus.

Endoscopic ultrasound (EUS)

EUS is a medical procedure which combines endoscopy with ultrasound to obtain images of organs within the chest and abdomen. During the procedure, a tiny ultrasound probe is introduced into the GI tract to screen for lesions in the surrounding areas. EUS may provide high-resolution images with a clear vision-feld despite the air in guts, and by virtue of short wavelength and high frequency sounds, it can detect lesions millimeters in size which are hardly competent for computed tomography, magnetic resonance imaging, and other modalities that typically detect lesions of comparatively larger, centimeter-sized volumes. As recommended by a number of specialty guidelines (2-6), EUS has now become an irreplaceable tool in the diagnosis of hepatobiliary malignancies, lung cancers, as well as neoplasms of the esophagus, stomach, colon and pancreas. EUS is also useful for tumor staging in invaded adjacent organs because of its high accuracy, and it may offer valuable information for therapeutic decision-making and prognosis estimation (7).

Furthermore, the development of linear echo endoscopes in the 1990s paved the way for a new approach: the ultrasound-guided fne needle puncture. Subsequently, EUS has evolved from a purely diagnostic imaging modality to an interventional procedure. The devices enable access into extraluminal solid organs or viscera by penetrating through the GI wall. Tissue samples from these locations or within the GI tract can be collected for cytopathological study. In addition, fluid can be drained and therapeutic agents injected to intended locations under direct vision.

EUS fine needle aspiration

EUS-guided fne needle aspiration (EUS-FNA) is currently performed as a routine examination at an increasing number of endoscopic centers. Biopsy samples obtained by EUSFNA are extremely important for cytological or histological examinations, because it is a safe and reliable method with notable effcacy (8). In particular, EUS-FNA is also crucial for determining the pathological nature of lesions which appear otherwise inaccessible and inconclusive (9). On its passage, the GI tract traverses through various anatomical regions closely related to a number of medical disciplines, including pulmonology, thoracic surgery, internal medicine, oncology, urology, gynecology, and endocrinology; thus, the use of EUS-FNA is not confined to GI oncology. In

10.3978/j.issn.1000-9604.2014.12.12

Submitted Nov 20, 2014. Accepted for publication Nov 24, 2014.