Retrospective interactive rigid fusion of ¹⁸F-FDG-PET and CT

Summary

Aim: This study investigates whether interactive rigid fusion of routine PET and CT data improves localization, detection and characterization of lesions compared to separate reading. For this purpose, routine PET and CT scans of patients with metastases from malignant melanoma were used. Patients, methods: In 34 patients with histologically confirmed malignant melanoma, FDG-PET and spiral CT were performed using clinical standard protocols. For all of these patients, gold standard was available. Clinical and radiological follow-up identified 82 lesions as definitely pathological. Two board-certified nuclear medicine physicians and two board-certified radiologists analyzed PET and CT images independently from each other. For each patient up to 32 anatomical regions (24 lymph node regions, 8 extranodular regions) were systematically classified. Discordant areas were interactively analyzed in manually and rigidly registered images using a commercially available fusion tool. No side-by-side reading was performed. Results: Image fusion disclosed that the evaluation of the PET images alone led to a mislocalization in 26 of 91 focally FDG enhancing lesions. The overall sensitivities of PET, CT, and image fusion were 85, 88, and 94%, respectively; the overall specificities of PET, CT and image fusion were 98, 95 and 100%, respectively. Image fusion exhibited statistically significant higher specificity values as compared with CT. Ten definitely malignant sites were false-negative in CT, but could be detected by PET. On the other hand, twelve metastases were false-negative in PET, but could be detected by CT. These included two lesions, which had a clear correlate on the PET image when the fused images were evaluated. On the whole, registration of the PET and CT images yielded additional diagnostic information in 44% of the definitely malignant lesions. Conclusion: Retrospective image fusion of independently obtained PET and CT data is particularly valuable in exactly localizing foci of abnormal FDG uptake and improves the detection of metastases of malignant melanoma.

Zusammenfassung

Ziel: Diese Studie untersucht, ob durch die interaktive starre Fusion von PET- und CT-Daten die Lokalisierbarkeit, Auffindung und Charakterisierung von Herden im Vergleich zur getrennten Analyse von PET und CT verbessert werden kann. Hierzu wurden im Routinebetrieb aufgenommene PET- und CT-Scans von Patienten mit malignem Melanom analysiert. Patienten, Methoden: Bei 34 Patienten mit malignem Melanom wurden eine Ganzkörper-FDG-PET und ein Spiral-CT durchgeführt. Für alle Patienten lag ein Goldstandard vor. Für 82 Läsionen konnte durch den weiteren klinischen und radiologischen Verlauf die Malignität bestätigt werden. Je zwei Nuklearmediziner und Radiologen führten unabhängig voneinander eine Befundung der PET bzw. CT-Bilder durch. Für jeden Patienten wurden 32 anatomische Lokalisationen (24 Lymphknotenstationen, 8 extranoduläre Stationen) systematisch evaluiert. Bei fehlender Übereinstimmung erfolgte anschließend die interaktive Befundung der manuell starr registrierten Bilddaten unter Verwendung eines kommerziell erhältlichen Fusionstools. Auf eine visuelle Korrelation wurde verzichtet. Ergebnisse: Bei der alleinigen Analyse der PET-Bilder wurden 26 von 91 fokalen FDG-Mehranreicherungen einer falschen anatomischen Struktur zugeordnet. Die Sensitivitäten von PET, CT und Bildfusion betrugen 85%, 88% bzw. 94%, die Spezifitäten 98%, 95% bzw. 100%. Die Spezifität der Bildfusion war statistisch signifikant höher als die der CT. Zehn definitiv maligne Herdbefunde waren im CT falsch-negativ und wurden erst nach Überlagerung mit dem PET-Bild entdeckt. Umgekehrt waren zwölf Metastasen in der PET falsch-negativ. Zwei dieser Herde zeigten ein eindeutiges Korrelat im PET, welches jedoch erst durch die Bildfusion als solches gesehen wurde. Insgesamt ergab die Analyse der fusionierten Bilder einen Informationsgewinn für 44 % der Metastasen. Schlussfolgerung: Die retrospektive Fusion von PET- und CT-Bildern ermöglicht die exakte Lokalisierung von Läsionen mit abnormaler FDG-Aufnahme und verbessert die Auffindung von Metastasen bei Patienten mit malignem Melanom.

Keywords

PET - spiralcomputedtomography - imagefusion - FDG - melanoma

Schlüsselwörter

PET - Spiral-CT - Bildfusion - FDG - Melanom

• References

• 1 Acland KM, O‘Doherty MJ, Russell-Jones R. The value of positron emission tomography scanning in the detection of subclinical metastatic melanoma. J Am Acad Dermatol 2000; 42: 606-11.
• 2 Amthauer H, Ruf J, Bohmig M. et al. Diagnosis of neuroendocrine tumours by retrospective image fusion: is there a benefit?. Eur J Nucl Med Mol Imaging 2004; 31: 342-8.
• 3 Antoch G, Forsting M. How much CT does PET/ CT need?. Nuklearmedizin 2004; 43: 141-2.
• 4 Antoch G, Saoudi N, Kuehl H. et al. Accuracy of whole-body dual-modality fluorine-18–2-fluoro- 2-deoxy-D-glucose positron emission tomography and computed tomography (FDG-PET/ CT) for tumor staging in solid tumors: comparison with CT and PET. J Clin Oncol 2004; 22: 4357-68.
• 5 Aquino SL, Asmuth JC, Alpert NM. et al. Improved radiologic staging of lung cancer with 2-¹⁸F-fluoro-2-deoxy-D-glucose-positron emission tomography and computed tomography registration. J Comput Assist Tomogr 2003; 27: 479-84.
• 6 Aquino SL, Asmuth JC, Moore RH. et al. Improved image interpretation with registered thoracic CT and positron emission tomography data sets. AJR Am J Roentgenol 2002; 178: 939-44.
• 7 Balch CM, Buzaid AC, Soong SJ. et al. Final version of the American Joint Committee on Cancer staging system for cutaneous melanoma. J Clin Oncol 2001; 19: 3635-48.
• 8 Bar-Shalom R, Yefremov N, Guralnik L. et al. Clinical performance of PET/CT in evaluation of cancer: additional value for diagnostic imaging and patient management. J Nucl Med 2003; 44: 1200-9.
• 9 Buchmann I, Reinhardt M, Elsner K. et al. 2-(fluorine- 18)fluoro-2-deoxy-D-glucose positron emission tomography in the detection and staging of malignant lymphoma. A bicenter trial. Cancer 2001; 91: 889-99.
• 10 Buell U, Wieres FJ, Schneider W. et al. ¹⁸FDG-PET in 733 consecutive patients with or without sideby- side CT evaluation: analysis of 921 lesions. Nuklearmedizin 2004; 43: 210-6.
• 11 Crippa F, Leutner M, Belli F. et al. Which kinds of lymph node metastases can FDG PET detect? A clinical study in melanoma. J Nucl Med 2000; 41: 1491-4.
• 12 Diffey BL. The future incidence of cutaneous melanoma within the U. K. Br J Dermatol 2004; 151: 868-72.
• 13 Fuster D, Chiang S, Johnson G. et al. Is ¹⁸F-FDG PET more accurate than standard diagnostic procedures in the detection of suspected recurrent melanoma?. J Nucl Med 2004; 45: 1323-7.
• 14 Herzog H, Tellmann L, Hocke C. et al. NEMA NU2–2001 Guided Performance Evaluation of Four Siemens ECAT PET Scanners. IEEE Trans Nucl Sci 2004; 51: 2662-9.
• 15 Holder Jr WD, White Jr RL, Zuger JH. et al. Effectiveness of positron emission tomography for the detection of melanoma metastases. Ann Surg 1998; 227: 764-71.
• 16 Hutton BF, Braun M, Thurfjell L. et al. Image registration: an essential tool for nuclear medicine. Eur J Nucl Med Mol Imaging 2002; 29: 559-77.
• 17 Jager PL, Slart RH, Corstens F. et al. PET-CT: a matter of opinion?. Eur J Nucl Med Mol Imaging 2003; 30: 470-1.
• 18 Kim JH, Czernin J, Allen-Auerbach MS. et al. Comparison between ¹⁸F-FDG PET, in-line PET/ CT, and software fusion for restaging of recurrent colorectal cancer. J Nucl Med 2005; 46: 587-95.
• 19 Leiter U, Meier F, Schittek B. et al. The natural course of cutaneous melanoma. J Surg Oncol 2004; 86: 172-8.
• 20 Löffler M, Weckesser M, Franzius C. et al. Malignant melanoma and ¹⁸F-FDG-PET: Should the whole body scan include the legs?. Nuklearmedizin 2003; 42: 167-72.
• 21 Nguyen AT, Akhurst T, Larson SM. et al. PET Scanning with ¹⁸F 2-fluoro-2-deoxy-D-glucose (FDG) in patients with melanoma. Benefits and limitations ¹⁸F-FDG PET scan in the staging of recurrent melanoma: additional value and therapeutic impact. Clin Positron Imaging 1999; 2: 93-8.
• 22 Nishioka T, Shiga T, Shirato H. et al. Image fusion between ¹⁸FDG-PET and MRI/CT for radiotherapy planning of oropharyngeal and nasopharyngeal carcinomas. Int J Radiat Oncol Biol Phys 2002; 53: 1051-7.
• 23 Noemayr A, Römer W, Hothorn T. et al. Anatomical accuracy of lesion localization by retrospective interactive rigid image registration between ¹⁸F-FDG-PET and X-Ray CT. Nuklearmedizin 2005; 44: 149-55.
• 24 Prichard RS, Hill AD, Skehan SJ. et al. Positron emission tomography for staging and management of malignant melanoma. Br J Surg 2002; 89: 389-96.
• 25 Riemann B, Schober O. Cross section Nuclear- Medicine. Nuklearmedizin 2002; 41: 1-2.
• 26 Rinne D, Baum RP, Hör G. et al. Primary staging and follow-up of high risk melanoma patients with whole-body ¹⁸F-fluorodeoxyglucose positron emission tomography: results of a prospective study of 100 patients. Cancer 1998; 82: 1664-71.
• 27 Römer W, Fiedler E, Pavel M. et al. Attenuation correction of SPECT images based on separately performed CT: Effect on the measurement of regional uptake values. Nuklearmedizin 2005; 44: 20-8.
• 28 Schaffler GJ, Groell R, Schoellnast H. et al. Digital image fusion of CT and PET data sets--clinical value in abdominal/pelvic malignancies. J Comput Assist Tomogr 2000; 24: 644-7.
• 29 Schmidt M, Eschner W, Dietlein M. et al. Established nuclear medicine techniques for tumour diagnosis (tumour SPECT): Can they still compete with ¹⁸F-FDG-PET?. Nuklearmedizin 2005; 44: 37-48.
• 30 Schoder H, Larson SM, Yeung HWD. PET/CT in oncology: Integration into clinical management of lymphoma, melanoma, and gastrointestinal malignancies. J Nucl Med 2004; 45: 72S-81.
• 31 Schoder H, Yeung HW, Gonen M. et al. Head and neck cancer: clinical usefulness and accuracy of PET/CT image fusion. Radiology 2004; 231: 65-72.
• 32 Stas M, Stroobants S, Dupont P. et al. ¹⁸F-FDG PET scan in the staging of recurrent melanoma: additional value and therapeutic impact. Melanoma Res 2002; 12: 479-90.
• 33 Steinert HC, Huch Boni RA, Buck A. et al. Malignant melanoma: staging with whole-body positron emission tomography and 2-¹⁸F-fluoro- 2-deoxy-D-glucose. Radiology 1995; 195: 705-9.
• 34 Swetter SM, Carroll LA, Johnson DL. et al. Positron emission tomography is superior to computed tomography for metastatic detection in melanoma patients. Ann Surg Oncol 2002; 9: 646-53.
• 35 Tsai CC, Tsai CS, Ng KK. et al. The impact of image fusion in resolving discrepant findings between FDG-PET and MRI/CT in patients with gynaecological cancers. Eur J Nucl Med Mol Imaging 2003; 30: 1674-83.
• 36 Tyler DS, Onaitis M, Kherani A. et al. Positron emission tomography scanning in malignant melanoma. Cancer 2000; 89: 1019-25.
• 37 Vansteenkiste JF, Stroobants SG, Dupont PJ. et al. FDG-PET scan in potentially operable non-small cell lung cancer: do anatometabolic PET-CT fusion images improve the localisation of regional lymph node metastases? The Leuven Lung Cancer Group. Eur J Nucl Med 1998; 25: 1495-501.
• 38 Wahl RL, Quint LE, Cieslak RD. et al. „Anatometabolic“ tumor imaging: fusion of FDG PET with CT or MRI to localize foci of increased activity. J Nucl Med 1993; 34: 1190-7.
• 39 Zimny M, Wildberger JE, Cremerius U. et al. Combined image interpretation of computed tomography and hybrid PET in head and neck cancer. Nuklearmedizin 2002; 41: 14-21.