The strong but nonspecific relationship between 18F-FDG uptake in the lower-extremity veins and venous thromboembolism

Abstract

Venous thromboembolism (VTE) can present as deep vein thrombosis (DVT) and/or acute pulmonary embolism (PE). In fluorine-18 fluorodeoxyglucose (18F-FDG) PET/CT, 18F-FDG activity along the deep veins of the lower extremities (LE) is often observed and, unless it is associated with focal intense activity, is not considered abnormal. However, anecdotally it has been associated with the placement of an inferior vena cava filter. In this short paper we intend to investigate this association. We found 10 patients who were investigated in the vascular laboratory by means of either LE or upper-extremity duplex or a chest computed tomography with PE protocol, or who had undergone the placement of an inferior vena cava filter between 27 April 2010 and 7 January 2013 and who had also undergone one or more 18F-FDG-PET scan(s) that included the LE. Seventeen patients without venous 18F-FDG uptake were added as controls. 18F-FDG uptake visualized in the LE was scored as the number of positive LE veins and the extent of the radiotracer uptake. The time intervals between the VTE event and the 18F-FDG-PET scan(s) were recorded. The time intervals between the most remote and the closest 18F-FDG-PET before a VTE event averaged 79 ± 101 and 49 ± 82 days, respectively, and the closest and the most remote 18F-FDG-PET after the VTE event averaged 58 ± 50 and 122 ± 124 days. The extent of uptake in the LE veins averaged 7 ± 2 for the patients with an acute DVT on LE duplex and 5 ± 3 for those with negative or chronic DVT on LE duplex (P=nonsignificant). Two patients (n=3 and 10) were negative for VTE events and had an extent of 0. The number of positive events correlated slightly with the extent of venous uptake (r=0.69). The 17 control patients without venous uptake on 18F-FDG-PET had no history of VTE. There was an association between LE venous uptake of 18F-FDG and risk for VTE. The association was not related to the location of the VTE, nor to the timing of the VTE.

The critical role of FDG-PET/CT imaging in assessing systemic manifestations of COVID-19 infection

“…Furthermore, we have noted that venous clots due to their high concentration of activated white cells are also readily visualized by FDG-PET ( Fig. 5) [23][24][25][26][27]. We believe this potential application of FDG-PET imaging will likely play a major role in evaluating and treating patients with [15] suspected venous thromboembolic disorders in the near future.…”

“…From the left to the right are the FDG-PETs 41 days after the PECCT, 47 days before, and 9 days after the positive BLE Duplex, which demonstrate improvement from 47 days before with visualization of bilateral CF and PV only, and 13 days before and 94 days after the negative BLE Duplex for acute DVT, which demonstrate progression of visualization of bilateral CF, PV, left PT, and left peroneal. BLE, bilateral lower extremities; CF, common femoral; DVT, deep vein thrombosis; PE, pulmonary embolism; PECCT, chest computed tomography with PE protocol; PT, posterior tibial; PV, popliteal vein; UE, upper extremity (reproduced with permission from Zhu HJ et al) [23] patients who had recovered from COVID-19 and assessed evidence for systemic inflammation by FDG-PET/CT imaging [30]. These investigators compared the findings in patients with those of control subjects with cancer but with negative follow-up FDG-PET/CT scans.…”

FDG-PET/CT in venous thromboembolism

“…This theory was, to some extent, corroborated by the findings in the abovementioned study by Rondina et al with its limited number of patients [12]. Conversely, Zhu et al [20] evaluated the potential for early diagnosis of VTE by correlating the occurrence of FDG-uptake in the lower extremities on scans performed prior to and after an established diagnosis of VTE. The results indicated a non-specific increase in FDG-uptake in the lower extremities in patients with subsequent VTE compared to controls without increased FDG-uptake and no history of VTE before or after the scan.…”

“…Of the included papers, five papers were on the diagnostic performance of PET/CT in DVT (n=3) or PE (n=3) [11][12][13][14][15], and four were on the ability of PET/CT to differentiate TT from BT [16][17][18][19]. Two papers presented data on changes in FDG uptake over time [12,20]. Three papers were prospective, and seven were retrospective.…”

Regarding “18F-GP1, a Novel PET Tracer Designed for High-Sensitivity, Low-Background Detection of Thrombi”

“…First, only very acute venous (and arterial) nonoccluding thrombi were assessable with 18 F-GP1 in the setup presented, but it remains unknown how the uptake is in older, chronic thrombi. This question has already been successfully evaluated using 18 F-FDG, with clear signs of declining 18 F-FDG avidity over time (10,11). Also, the catheter-based method favors thrombus formation in the venous bed and major arteries, but there is no evidence of any 18 F-GP1 uptake related to pulmonary embolism-a major drawback of 18 F-FDG (9,12).…”