Soft Tissue Metastases Detected by F-18 FDG PET/CT in Gastrointestinal System Malignancies

Öz

Objective: Metastases in gastrointestinal system malignancies mainly occur in regional lymph nodes. Among distant metastases, soft tissue metastases are rarely observed and are mostly reported as case reports in the literature. Although methods such as direct X-ray and Magnetic Resonance (MR) are used to detect soft tissue metastases, F-18 FDG PET/CT gains importance in such patients both in terms of determining whether there are other metastases and detecting soft tissue metastases. Our study aimed to determine the importance of F-18 FDG PET/CT in detecting soft tissue metastasis and the incidence and characteristics of soft tissue metastases in patients with gastrointestinal system malignancies. Methods: We retrospectively analyzed 866 patients diagnosed with stomach, esophageal, and colorectal cancers who underwent F-18 FDG PET/CT. STM was defined as metastatic involvement of skeletal muscles or subcutaneous tissues. Locations of the lesions and their metabolic activities were recorded. Results: The incidence of STM in esophageal, stomach, and colon cancers among 866 patients examined was 2,4% (4/164), 2.7% (13/475), and 0.4% (1/227), respectively. In patients with subcutaneous metastases, the mean SUVmax value of the lesions was 4.3, and the density on CT was 33.2 HU. In intramuscular metastases, the mean SUVmax value was 6.71, and CT density was close to the soft tissue density (mean HU: 27.1). Most STMs were clinically asymptomatic and detected incidentally during whole-body PET/CT imaging. Conclusion: Although STM is an infrequent presentation in GIS malignancies, its detection is vital for accurate staging and management. F-18 FDG PET/CT is a superior diagnostic tool compared to conventional imaging for identifying these often-overlooked metastatic sites due to its ability to detect metabolic changes before morphological alterations.

Anahtar Kelimeler

• F-18 FDG PET/CT
• gastrointestinal system malignancies
• soft tissue metastasis

Etik Beyan

Ethics committee approval was obtained from Erzurum Regional Training and Research Hospital Local Ethics Committee (Date: July 20, 2020, Number: 2020/14-153).

Gastrointestinal Sistem Malignitelerinde F-18 FDG PET/BT ile Saptanan Yumuşak Doku Metastazları

Öz

Amaç: Gastrointestinal sistem malignitelerinde metastazlar esas olarak bölgesel lenf nodlarında meydana gelir. Uzak metastazlar arasında yumuşak doku metastazları nadir görülmekte olup literatürde çoğunlukla olgu sunumları şeklinde bildirilmektedir. YDM tespiti için direkt grafi ve Manyetik Rezonans gibi yöntemler kullanılsa da, F-18 FDG PET/BT hem ek metastazların varlığını belirleme hem de YDM’leri saptama açısından önem kazanmaktadır. Çalışmamızın amacı, GİS malignitelerinde F-18 FDG PET/BT’nin YDM saptamadaki önemini, YDM insidansını ve özelliklerini belirlemektir. Yöntemler: F-18 FDG PET/BT çekilen mide, özofagus ve kolorektal kanser tanılı 866 hasta retrospektif olarak analiz edildi. YDM; iskelet kaslarının veya deri altı (subkütan) dokuların metastatik tutulumu olarak tanımlandı. Lezyonların lokalizasyonları ve metabolik aktiviteleri kaydedildi. Bulgular: İncelenen 866 hasta arasında YDM insidansı özofagus, mide ve kolon kanserlerinde sırasıyla %2,4 (4/164), %2,7 (13/475) ve %0,4 (1/227) olarak saptandı. Subkütan metastazı olan hastalarda lezyonların ortalama SUVmax değeri 4,3, BT dansitesi ise 33,2 HU idi. İntramüsküler metastazlarda ortalama SUVmax değeri 6,71 iken, BT dansitesi yumuşak doku dansitesine yakındı (ortalama HU: 27,1). YDM'lerin çoğu klinik olarak asemptomatikti ve tüm vücut PET/BT görüntülemesi sırasında rastlantısal olarak saptandı. Sonuç: GİS malignitelerinde YDM nadir bir sunum olsa da, tespiti doğru evreleme ve tedavi yönetimi için hayati önem taşır. F-18 FDG PET/BT, morfolojik değişikliklerden önce metabolik değişiklikleri saptayabilme yeteneği sayesinde, sıklıkla gözden kaçan bu metastatik bölgelerin belirlenmesinde konvansiyonel görüntüleme yöntemlerine göre üstün bir tanı aracıdır.

Anahtar Kelimeler

• F-18 FDG PET/BT
• gastrointestinal sistem maligniteleri
• yumuşak doku metastazı

Etik Beyan

Etik kurul onayı Erzurum Bölgesel Eğitim ve Araştırma Hastanesi Yerel Etik Kurulu'ndan (Tarih: 20 Temmuz 2020, Sayı: 2020/14-153) alınmıştır.

Kaynakça

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