11C-methionine- and 18F-FDG-PET double-negative metastatic brain tumor from lung adenocarcinoma with paradoxical high 18F-FDG uptake: A case report

Tanahashi, Kuniaki; Hirano, Mari; Chalise, Lushun; Tsugawa, Takahiko; Okumura, Yuka; Hase, Takashi; Ohka, Fumiharu; Motomura, Kazuya; Takeuchi, Kazuhito; Nagata, Yuichi; Nakahara, Norimoto; Hashimoto, Naozumi; Saito, Ryuta

doi:10.25259/sni_264_2022

Cited by 1 publication

(2 citation statements)

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“…This showed that the T1/T2 mismatch was not always reliable in excluding the possibility of recurrence [ 10 , 13 ]. In contrast, the increased uptake of 11 C-Met-PET was useful for estimating pathology [ 16 ]. Anti-cancer medication was not consistently administered in the present case because of IPF.…”

Section: Discussionmentioning

confidence: 99%

“…Given the relatively high dose prescribed to the tumor and the T1/T2 mismatch, tumor progression (≥20% and/or ≥5 mm enlargement following the nadir response of an enhancing lesion) was deemed to mainly reflect ARE [4,10,13]. However, because tumor recurrence could not be excluded regarding the progressive enlargement of the enhancing lesion, 11 C-methionine (Met) positron emission tomography (PET) was acquired at 23.1 months, which showed increased uptake over a wide area of the enhancing lesion, suggesting the existence of a viable tumor (Figure 6) [16]. Therefore, minimally invasive salvage surgery was planned considering that the impaired pulmonary function was not amenable to general anesthesia, and a total lesionectomy was performed under local anesthesia [17].…”

Section: Case Presentationmentioning

confidence: 99%

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Local Control Failure After Five-Fraction Stereotactic Radiosurgery Alone for Symptomatic Brain Metastasis From Squamous Cell Lung Carcinoma Despite 43 Gy to Gross Tumor Margin With Internal Steep Dose Increase and Tumor Shrinkage During Irradiation

Ohtakara¹,

Tanahashi²,

Kamomae³

et al. 2023

Cureus

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Five-fraction (fr) stereotactic radiosurgery (SRS) is increasingly being applied to large brain metastases (BMs) >2-3 cm in diameter, for which 30-35 Gy is the commonly prescribed dose. Since 2018, to further enhance both safety and efficacy, we have limited the five-fr SRS to approximately ≤3 cm BMs and adopted our own modified dose prescription and distribution: 43 and 31 Gy cover the boundaries of the gross tumor volume (GTV) and 2 mm outside the GTV, respectively, along with a steep dose increase inside the GTV boundary, that is, an intentionally very inhomogeneous GTV dose. Herein, we describe a case of symptomatic BM treated with five-fr SRS using the above policy, which resulted in a maximum tumor response with nearly complete remission (nCR) followed by gradual tumor regrowth despite obvious tumor shrinkage during irradiation. A 71-year-old man who had previously undergone surgery for squamous cell carcinoma (SCC) of the lungs presented with right-sided hemiparesis attributed to the para-falcine BM (27 mm in maximum diameter, 5.38 cm 3 ). The BM was treated with five-fr SRS, with 99.2% of the GTV covered with 43 Gy and 59% isodose. Neurological symptoms improved during SRS, and obvious tumor shrinkage and mitigation of perilesional edema were observed upon completion of SRS. No subsequent anti-cancer pharmacotherapy was administered due to idiopathic pulmonary fibrosis (IPF). Despite a maximum response with nCR at four months, the tiny residual enhancing lesion gradually enlarged from 7.7 months to 22.7 months without neurological worsening. Although a consistent T1/T2 mismatch suggested the dominance of brain radionecrosis, 11 C-methionine positron emission tomography showed increased uptake in the enhancing lesion. Pathological examination after total lesionectomy at 24.6 months revealed viable tumor tissue. Post-SRS administration of nintedanib for IPF may have provided some anti-tumor efficacy for lung SCC and may mitigate the adverse effects of SRS. The present case suggests that even ≥43 Gy with ≤60% isodose to the GTV boundary and ≥31-35 Gy to the 2 mm outside the GTV are insufficient to achieve long-term local tumor control by five-fr SRS alone in some large BM from lung SCC.

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Section: Discussionmentioning

confidence: 99%