HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nakamoto, Y. Articles by Senda, M. Search for Related Content PubMed PubMed Citation Articles by Nakamoto, Y. Articles by Senda, M. Social Bookmarking                      What's this?

Accuracy of Image Fusion Using a Fixation Device for Whole-Body Cancer Imaging

Department of Image-Based Medicine, Institute of Biomedical Research and Innovation, 2-2 Minatojima Minamimachi, Chuo-Ku, Kobe 650-0047, Japan.

Received May 6, 2004; accepted after revision September 22, 2004.

 
Address correspondence to Y. Nakamoto.

Abstract

Top Abstract Introduction Subjects and Methods Results Discussion References

 
OBJECTIVE. The purpose of this study was to evaluate the clinical feasibility of a simple image fusion technique with PET and CT images acquired separately using a vacuum cushion as a fixation device.

SUBJECTS AND METHODS. Forty-four patients underwent whole-body PET using ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) followed by CT with IV contrast material. The patients were carefully fixed in an individually molded cushion to provide the same positioning for both examinations. The PET and CT images were fused on a workstation by using the lower margin of the urinary bladder as a reference. The degree of misregistration was evaluated for the physiologic uptake of the liver and kidneys and for the pathologic uptake of lesions.

RESULTS. The average deviation of the center point of the liver between the two images was 6.6 ± 8.7 (SD) mm in the craniocaudal direction, 1.9 ± 5.1 mm in the anteroposterior direction, and 2.3 ± 7.0 mm in the right-left direction. This value in the craniocaudal direction was 4.7 ± 8.7 mm in the right kidney and 4.0 ± 8.8 mm in the left kidney. Above the diaphragm, the deviations of the center point of movable and static lesions were 11.7 ± 3.4 mm and 10.4 ± 5.3 mm, respectively. Below the diaphragm, those of movable and static lesions were 9.7 ± 2.5 mm and 6.9 ± 2.9 mm, respectively.

CONCLUSION. Our preliminary data indicate that this technique is a simple and practical method for manual image fusion that may be acceptable in clinical settings.

Introduction

Top Abstract Introduction Subjects and Methods Results Discussion References

 
PET using ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) has been established as a functional imaging tool in diagnostic oncologic imaging [1-3]. Many reports have shown the clinical usefulness of FDG PET for the management of cancer patients in determining the appropriate therapeutic strategy. However, because of the poor morphologic information from PET, reference to conventional morphologic techniques, such as CT, is considered essential to interpret PET images effectively and accurately.

Recently, combined PET/CT scanners were developed to address this issue, and the clinical usefulness of this new technique has been recognized [4-7]. The PET/CT device enables us to obtain the data sets of both PET and CT images with the patient at the same position in a single examination without repositioning, yielding the precise location of the metabolic abnormalities superimposed on high-spatial-resolution CT. In addition, acquired CT data in PET/CT are used not only for image fusion but also for attenuation correction, which contributes to shortening the total scanning time and to a higher throughput because a conventional transmission scan using an external source is no longer required.

Although an increasing number of PET centers are installing PET/CT scanners instead of dedicated PET scanners, not every institute can afford them. In the meantime, many hospitals already have dedicated PET cameras and MDCT scanners. If the PET and CT images can be fused on a computer after each data set is acquired with a dedicated device, it could have a major impact in clinical situations. A manual fusion technique has been reported in the head and neck area [8-10]. However, for the rest of the body, accurate image registration of PET and CT has been challenging because of the variability of patient posture and positioning and the movement of internal organs.

The purpose of this study was to investigate the clinical feasibility of a simple manual fusion technique for PET and CT images acquired separately—but with the patient in the same position—using a vacuum cushion as a fixation device that is widely used to fix patients undergoing radiation therapy by examining the degree of misregistration.

View larger version (135K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1A. —Photographs show patient on vacuum cushion undergoing PET and CT. Patient was fixed in individually molded cushion, and PET was performed first (A), followed by CT (B) with the patient on the same vacuum cushion. Once air is drawn from cushion, this fixation device is rigid enough so that patient is in same position for both examinations.

View larger version (134K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1B. —Photographs show patient on vacuum cushion undergoing PET and CT. Patient was fixed in individually molded cushion, and PET was performed first (A), followed by CT (B) with the patient on the same vacuum cushion. Once air is drawn from cushion, this fixation device is rigid enough so that patient is in same position for both examinations.

Top Abstract Introduction Subjects and Methods Results Discussion References

PET and CT
After at least a 4-hr fast, patients received 111-148 MBq (3-4 mCi) of FDG, which was synthesized by the Merrifield method [11]. At 50 min after contrast injection, patients were urged to void. Then, they were positioned in a large (200 x 60 x 5 cm) vacuum cushion (ESFORM, Engineering System) on the bed of a PET scanner with their arms over their head (Fig. 1A). The rugged and flexible cushion is filled with tiny polystyrene beads and molds to the patient's body contours. When air is drawn from the cushion, it becomes a rigid but comfortable individual cradle for the anatomic area being immobilized. After positioning the patient, we marked a median line from the navel to the sternum level; bilateral horizontal longitudinal lines; and a transverse line, indicating the start of scanning in the upper thigh, on the surface of the skin.

The PET studies were performed using either an ECAT Exact 47 or an ECAT Exact HR+ PET Camera (Siemens/CTI). These devices simultaneously acquire 47 planes over a 16.2-cm axial field of view (ECAT Exact 47) or 63 planes over a 15.5-cm axial field of view (ECAT Exact HR+). After the patients were positioned as described, a static emission scan was obtained with 2-3 min of acquisition at each bed position covering from the upper thigh to the meatus of the ear. Then, a transmission scan using a germanium-68-gallium-68 ring was obtained over the same area for 2 min per bed position. Three-dimensional acquisition was performed in this study. Attenuation-corrected images were made using an ordered-subsets expectation maximization iterative reconstruction algorithm (3 iterations, 16 subsets).

After PET scanning was completed, patients were urged to void again and were moved to the CT room. A CT scan was obtained with the patient in the same molded vacuum cushion (Fig. 1B). The CT device was a 4-MDCT scanner (Acquilion, Toshiba Medical Systems). The technical parameters used for MDCT were as follows: a detector-row configuration of 3 x 5.5 mm, a pitch of 6:1 (high-speed mode), a gantry rotation speed of 0.8 sec, a table speed of 30 mm per gantry rotation, 140 kV of peak energy, and 200-450 mA of electric current with real exposure control. During scanning, the patients were asked to perform shallow breathing for 20-30 sec. Only contrast-enhanced CT was acquired during the arteriovenous phase—that is, 80-90 sec after IV injection of 100 mL of iohexol (Omnipaque 300, Daiichi Pharmaceutical). For elderly or light patients—for example, a patient who is more than 70 year old or weighs less than 50 kg—100 mL of Omnipaque 240 was used instead of Omnipaque 300.

Image Processing and Analysis
Both CT and PET data sets were transferred to a workstation (ULTRA60, SUN Microsystems). PET images, which had been enlarged by multiplying a zooming factor to match the field of view of the CT images (50 cm), were interpolated into a matrix size of 512 x 512 and a 5-mm interval using software (Dr. View, Asahikasei-Joho Systems). The slice showing the lower margin of the urinary bladder was determined for both the CT and the modified PET images, and the PET images were shifted craniocaudal to match the CT images. Thus, the two sets of images were merged on a pixel-to-pixel basis with the same slice showing the lower margin of the bladder.

For evaluation of misregistration, margins (upper and lower, right and left, and anterior and posterior) of the physiologic uptake of the liver were determined in CT and PET images first, and the difference between the two images was evaluated for each margin and their center point. The upper and lower margins were determined by referring to the reconstructed images with 5-mm thickness and 5-mm interval. The misregistration for the upper and lower margins and for the center was also assessed for the bilateral kidneys. In addition, for the pathologic uptake, we evaluated the misregistration, as Cohade et al. [12] reported. Briefly, the upper and lower margins of the lesions were determined first, and the center slice was selected in the craniocaudal direction. The coordinates of the center point of the lesion were then determined on the center slice, and the 3D deviation between the two techniques was calculated. The lesions were classified into four groups: movable sites above the diaphragm, such as lung metastasis (group A); static sites above the diaphragm, such as mediastinal lymph nodes (group B); movable sites below the diaphragm, such as metastasis to the liver or the peritoneum (group C); and static sites below the diaphragm, such as paraaortic lymph nodes or local recurrence of rectal cancer (group D). The average values of the lesions were compared among the groups using the one-factor analysis of variance test. Finally, to investigate whether the degree of mismatch depends on a patient's body, we assessed the correlation between the body mass index and displacement of the center point of the pathologic uptake by means of the Pearson's correlation coefficient.

View larger version (10K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2. —Graph shows differences between PET and CT for each margin in liver. Mismatches between PET and CT images of 0-10 mm (white bars), 10-20 mm (gray bars), and more than 20 mm (black bars) are shown. In liver, percentage of consistency is low in lower and upper margins, suggesting mislocalization due to respiratory motion.

View larger version (14K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3A. —Graphs show average displacement and SD of center of PET images and center of CT images. Compared with CT images, PET images generally tended to show center of organs cephalad, posterior, and shifted to right. Graph shows average displacement ± SD (bars) for liver. C-C = craniocaudal, A-P = anteroposterior, R-L = right-left, = craniocaudal, = anteroposterior, = right-left.

View larger version (10K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3B. —Graphs show average displacement and SD of center of PET images and center of CT images. Compared with CT images, PET images generally tended to show center of organs cephalad, posterior, and shifted to right. Graph shows average displacement ± SD (bars) for right () and left () kidneys.

Top Abstract Introduction Subjects and Methods Results Discussion References

View larger version (11K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4. —Graph shows average deviation of center of pathologic uptake between PET and CT images with mean ± SD (bar). Lesions were classified into four groups—that is, pulmonary nodules (group A), mediastinal and supraclavicular lymph nodes or pleural dissemination (group B), liver metastasis or peritoneal dissemination (group C), and paraaortic and inguinal lymph nodes or local recurrence of rectal carcinoma (group D). Although respiratory motion may have influenced localization between the two techniques, especially in groups A and C, no significant differences were observed among the groups (one-factor analysis of variance, p = 0.098).

View larger version (12K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5. —Graph shows relationship between patient body mass index and 3D displacement of the center of pathologic lesions. No significant correlation was observed (r = -0.047, p = 0.74), indicating that patient's body did not affect deviation of pathologic lesions between the two techniques.

Figures 6A, 6B, 6C, 6D, 6E, and 6F shows images from a representative case of recurrent colon cancer that were obtained with this technique. A focal uptake on PET corresponding to the disseminated nodule located behind the bladder may have been difficult to detect only on PET images because it is hard to differentiate pathologic uptake from the physiologic uptake of the right ureter (Figs. 6A, 6B, and 6C). Because the abnormality was depicted on CT, this finding was interpreted as a lesion. On the other hand, another disseminated lesion was hard to recognize as recurrence only on CT images. With the assistance of PET, this finding was also easily interpreted as positive for recurrence (Figs. 6D, 6E, and 6F).

View larger version (98K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6A. —47-year-old man with suspected recurrent colon cancer. CT image shows mass (arrow) that was accurately diagnosed as positive for recurrent colon cancer.

View larger version (69K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6B. —47-year-old man with suspected recurrent colon cancer. PET image that corresponds to A shows intense uptake located behind bladder (arrow), but finding may be difficult to recognize as abnormal only by PET image because it is hard to differentiate it from physiologic uptake of right ureter.

View larger version (73K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6C. —47-year-old man with suspected recurrent colon cancer. Fused image of CT (A) and PET (B) shows mass (arrow).

View larger version (99K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6D. —47-year-old man with suspected recurrent colon cancer. CT image (D) and PET image (E) show focus (arrow), but diagnosis is difficult.

View larger version (82K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6E. —47-year-old man with suspected recurrent colon cancer. CT image (D) and PET image (E) show focus (arrow), but diagnosis is difficult.

View larger version (70K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6F. —47-year-old man with suspected recurrent colon cancer. Fused image of CT (D) and PET (E) clearly shows dissemination (arrow). These lesions were confirmed by surgery.

Discussion

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Articles on image coregistration have been published since the early 1990s [13-16]. With the progress in computer software, recent articles have shown that multitechnique image fusion can be easily achieved using software without excessive time [17-20]. However, to our knowledge, few reports have mentioned a practical image fusion technique for PET and CT images of the entire body. Thus, we tried to fuse two images from the neck to the mid thigh with software, and we evaluated the degree of misregistration.

The extra time required for positioning in this system is 3-4 min for each examination, and the computing time for registration on software is less than 5 min total. Slomka et al. [19] showed that they have developed a technique for automated registration of CT and PET that required less than 40 sec for the linear component and less than 30 sec for the nonlinear component for a typical PET scan in four to six bed positions. Shekhar et al. [20] reported that registration of whole-body CT and PET images needed only 45-70 sec using a mutual information-based technique. Compared with these software-based approaches, our methods require more processing time, but it may be because of our relatively old-fashioned hardware. This method, which requires a vacuum cushion and commercially available software, yields relatively precise fusion images of CT with contrast material and FDG PET from the neck to the thigh that are considered acceptable for routine clinical use.

Forster et al. [18] showed that better registration was obtained with external markers than with internal markers [19]. Indeed, if physiologic uptake of the liver and kidney is used, respiratory motion of the liver or inhomogeneous accumulation in the kidney may cause larger misregistration than our method. We used the lower margin of the bladder as an internal marker instead because this portion, which is usually seen just behind the pubic symphysis, is generally fixed and is easy to detect on both PET and CT images. Moreover, it saves preparation time because we do not have to fix external markers to the body surface.

Goerres et al. [21] showed that CT should be performed during the normal expiratory phase to minimize misregistration due to the respiratory motion. In our study, patients were allowed shallow breathing because it can be painful to stop breathing for about 30 sec during CT, especially for elderly patients. In this investigation, mismatches were observed: More were seen in the upper and lower margins of the liver than in other margins, which may be because of respiratory motion. If CT had been performed during the normal expiratory phase, the degree of misregistration might have been reduced. However, for visual interpretations in clinical settings, it is not always necessary to get perfect registration. Therefore, we believe that free shallow breathing during CT is a good alternative, as Goerres et al. [22] indicated in another report.

The data we have presented are comparable to the results published for a combined PET/CT imaging device. For example, Goerres et al. [23] showed 0.5-14.7 mm of deviation for pulmonary lesions and Cohade et al. [12] showed average displacement of 7.6 mm in the thoracic area, which was more prominent in lesions located in the lower lung field. In addition, Nakamoto et al. [24] evaluated the degree of misregistration of FDG-avid abdominal organs, such as the liver and kidneys. According to that report, the average displacements of the center point in the liver between CT and germanium-corrected PET images were approximately 10 mm in the craniocaudal direction, 4 mm in the anteroposterior direction, and 9 mm in the right-left direction. Moreover, the average displacement was approximately 3 mm in the craniocaudal direction in the bilateral kidneys. The degrees of misregistration in our results in thoracic and abdominal areas were comparable to these reports evaluating PET/CT scanners. Two lesions in group B showed a displacement that was more than 2 cm. This large displacement may be due to poor repositioning of the patient before CT. Therefore, careful positioning of the patient during CT is significant when using this method.

There are some advantages of our proposed technique. It is simple and needs a small amount of extra time (3 min) for positioning the patient for each examination. The fusion software is commercially available, and no specific algorithm for fusion is necessary. Compared with other software-based approaches, this method also needs a small amount of computing time (5 min), and compared with the cost of a combined PET/CT scanner, this method is cost-effective. It may be applied in institutes where stand-alone CT and PET scanners are ready to use by preparing a fixation device and software. Because patients do not need to undergo CT twice—that is, diagnostic CT and PET/CT—redundant radiation exposure can be avoided, although irradiation by the external source for the transmission scan is unavoidable. Because it remains unknown whether this method may affect the diagnostic accuracy or how disparate the diagnostic accuracy is between this method and an in-line PET/CT system, further investigations are necessary.

On the other hand, there are some disadvantages associated with this method. Surgery for rectal cancer often changes the shape of the bladder. External markers would be necessary in such cases instead of referring to the lower edge of the bladder in a fusion process as an internal marker. Furthermore, for patients with stiff and painful shoulders, holding the arms up during scanning would be painful. Because the gantry of the PET device is generally smaller than that of a CT scanner, scanning of the neck area with the patient's arms up would be difficult in such cases. As far as visual interpretation is concerned, our method could be acceptable in clinical situations. However, when we apply it to radiation therapy planning, greater registration accuracy is required [25, 26]. For misregistration to be minimized, synchronized scanning while monitoring breathing may be necessary [27].

In conclusion, these preliminary data suggest that this method could be a simple and clinically acceptable technique for achieving image fusion between PET and CT. Although a fused image can be obtained much easier on a PET/CT system, our fusion technique may provide a simple, easy, and less costly alternative. The critical test will be to determine how disparate is the diagnostic accuracy between the two techniques.

References

Top Abstract Introduction Subjects and Methods Results Discussion References

 

1. Bar-Shalom R, Valdivia AY, Blaufox MD. PET imaging in oncology. Semin Nucl Med2000; 30:150 -185[Medline]
2. Bomanji JB, Costa DC, Ell PJ. Clinical role of positron emission tomography in oncology. Lancet Oncol2001; 2:157 -164[Medline]
3. Hustinx R, Benard F, Alavi A. Whole-body FDG-PET imaging in the management of patients with cancer. Semin Nucl Med2002; 32:35 -46[Medline]
4. Beyer T, Townsend DW, Brun T, et al. A combined PET/CT scanner for clinical oncology. J Nucl Med2000; 41:1369 -1379[Abstract/Free Full Text]
5. Townsend DW, Beyer T, Blodgett TM. PET/CT scanners: a hardware approach to image fusion. Semin Nucl Med2003; 33:193 -204[Medline]
6. Cohade C, Wahl RL. Applications of positron emission tomography/computed tomography image fusion in clinical positron emission tomography: clinical use, interpretation methods, diagnostic improvements. Semin Nucl Med2003; 33:228 -237[Medline]
7. Schoder H, Erdi YE, Larson SM, Yeung HW. PET/CT: a new imaging technology in nuclear medicine. Eur J Nucl Med Mol Imaging 2003;30:1419 -1437[Medline]
8. Jabour BA, Choi Y, Hoh CK, et al. Extracranial head and neck: PET imaging with 2-[F-18]fluoro-2-deoxy-D-glucose and MR imaging correlation. Radiology1993; 186:27 -35[Abstract/Free Full Text]
9. Uematsu H, Sadato N, Yonekura Y, et al. Coregistration of FDG PET and MRI of the head and neck using normal distribution of FDG. J Nucl Med 1998;39:2121 -2127[Abstract/Free Full Text]
10. Sercarz JA, Bailet JW, Abemayor E, Anzai Y, Hoh CK, Lufkin RB. Computer coregistration of positron emission tomography and magnetic resonance images in head and neck cancer. Am J Otolaryngol1998; 19:130 -135[Medline]
11. Toorongian SA, Mulholland GK, Jewett DM, Bachelor MA, Kilbourn MR. Routine production of 2-deoxy-2-[18F]fluoro-D-glucose by direct nucleophilic exchange on a quaternary 4-aminopyridinium resin. Int J Rad Appl Instrum B 1990;17:273 -279[Medline]
12. Cohade C, Osman M, Marshall LN, Wahl RN. PET-CT: accuracy of PET and CT spatial registration of lung lesions. Eur J Nucl Med Mol Imaging 2003;30:721 -726[Medline]
13. Liehn JC, Loboguerrero A, Perault C, Demange L. Superimposition of computed tomography and single photon emission tomography immunoscintigraphic images in the pelvis: validation in patients with colorectal or ovarian carcinoma recurrence. Eur J Nucl Med1992; 19:186 -194[Medline]
14. Wahl RL, Quint LE, Cieslak RD, Aisen AM, Koeppe RA, Meyer CR. "Anatometabolic" tumor imaging: fusion of FDG PET with CT or MRI to localize foci of increased activity. J Nucl Med1993; 34:1190 -1197[Abstract/Free Full Text]
15. Yu JN, Fahey FH, Gage HD, et al. Intermodality, retrospective image registration in the thorax. J Nucl Med1995; 36:1333 -1338 [Erratum in J Nucl Med 1996;37:23]
16. Perault C, Schvartz C, Wampach H, Liehn JC, Delisle MJ. Thoracic and abdominal SPECT-CT image fusion without external markers in endocrine carcinomas: The Group of Thyroid Tumoral Pathology of Champagne-Ardenne. J Nucl Med1997; 38:1234 -1242[Abstract/Free Full Text]
17. Kashiwagi T, Yutani K, Fukuchi M, et al. Correction of nonuniform attenuation and image fusion in SPECT imaging by means of separate X-ray CT. Ann Nucl Med2002; 16:255 -261[Medline]
18. Forster GJ, Laumann C, Nickel O, Kann P, Rieker O, Bartenstein P. SPET/CT image co-registration in the abdomen with a simple and cost-effective tool. Eur J Nucl Med Mol Imaging2003; 30:32 -39[Medline]
19. Slomka PJ, Dey D, Przetak C, Aladl UE, Baum RP. Automated 3-dimensional registration of stand-alone (18)F-FDG whole-body PET with CT. J Nucl Med2003; 44:1156 -1167[Abstract/Free Full Text]
20. Shekhar R, Zagrodsky V, Castro-Pareja CR, Walimbe V, Jagadeesh JM. High-speed registration of three- and four-dimensional medical images by using voxel similarity. RadioGraphics2003; 23:1673 -1681[Abstract/Free Full Text]
21. Goerres GW, Kamel E, Heidelberg TN, Schwitter MR, Burger C, von Schulthess GK. PET-CT image co-registration in the thorax: influence of respiration. Eur J Nucl Med Mol Imaging2002; 29:351 -360[Medline]
22. Goerres GW, Burger C, Schwitter MR, Heidelberg TN, Seifert B, von Schulthess GK. PET/CT of the abdomen: optimizing the patient breathing pattern. Eur Radiol2003; 13:734 -739[Medline]
23. Goerres GW, Kamel E, Seifert B, et al. Accuracy of image coregistration of pulmonary lesions in patients with non-small cell lung cancer using an integrated PET/CT system. J Nucl Med2002; 43:1469 -1475[Abstract/Free Full Text]
24. Nakamoto Y, Tatsumi M, Cohade C, et al. Accuracy of image fusion of normal upper abdominal organs visualized with PET/CT. Eur J Nucl Med Mol Imaging 2003;30:597 -602[Medline]
25. Cai J, Chu JC, Recine D, et al. CT and PET lung image registration and fusion in radiotherapy treatment planning using the chamfer-matching method. Int J Radiat Oncol Biol Phys1999; 43:883 -891[Medline]
26. Paulino AC, Thorstad WL, Fox T. Role of fusion in radiotherapy treatment planning. Semin Nucl Med2003; 33:238 -243[Medline]
27. Nehmeh SA, Erdi YE, Ling CC, et al. Effect of respiratory gating on quantifying PET images of lung cancer. J Nucl Med2002; 43:876 -881[Abstract/Free Full Text]

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				T. Z. Wong, E. K. Paulson, R. C. Nelson, E. F. Patz Jr., and R. E. Coleman Practical Approach to Diagnostic CT Combined with PET Am. J. Roentgenol., March 1, 2007; 188(3): 622 - 629. [Abstract] [Full Text] [PDF]

				Y. Nakamoto, S. Sakamoto, T. Okada, M. Senda, T. Higashi, T. Saga, and K. Togashi Clinical Value of Manual Fusion of PET and CT Images in Patients with Suspected Recurrent Colorectal Cancer Am. J. Roentgenol., January 1, 2007; 188(1): 257 - 267. [Abstract] [Full Text] [PDF]

				K. Brechtel, M. Klein, M. Vogel, M. Mueller, P. Aschoff, T. Beyer, S. M. Eschmann, R. Bares, C. D. Claussen, and A. C. Pfannenberg Optimized Contrast-Enhanced CT Protocols for Diagnostic Whole-Body 18F-FDG PET/CT: Technical Aspects of Single-Phase Versus Multiphase CT Imaging J. Nucl. Med., March 1, 2006; 47(3): 470 - 476. [Abstract] [Full Text] [PDF]

This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nakamoto, Y. Articles by Senda, M. Search for Related Content PubMed PubMed Citation Articles by Nakamoto, Y. Articles by Senda, M. Social Bookmarking                      What's this?