# The Fusion of MRI and CT in the Planning of Bracotherapy for Cancer of the Uterine Cervix
## 3 Results  
Between January 2019 and August 2021, 53 patients were treated with intracerebral IGABT. Six patients received brachytherapy without adaptive MRI planning and were excluded from quantitative evaluation. Forty-seven patients could be evaluated. The patients were between 29 and 80 years old (average 52 years). Of the patients, 18.9% had cT1 carcinoma, 45.3% had cT2 carcinoma, 28.3% had cT3 carcinoma, and 7.5% had cT4 carcinoma; 34% had no metastases in regional pelvic lymph nodes N0, while 66% had metastases in regional lymph nodes N1; and 73.6% had no distant metastases M0, while 26.4% had paraaortic lymph node metastases pM1 (Lym). Patients with visceral metastases were not among the treated. None of the patients had highly differentiated carcinoma G1, 51% of patients had G2 carcinoma, while 49% had G3 carcinoma; 90.6% of patients had no invasion of lymphatic vessels L0, while 9.4% of patients had L1; 86.8% of patients had V0, while 13.2% of patients had infiltration of blood vessels V1; and 86.8% of these cases were squamous cell carcinoma, 9.4% were adenocarcinoma, and 3.8% were small cell or adenosquamous.  
For the acquisition (vibe, thrive, LAVA, and T2-space) of MRI 1, 69.8% of patients had a 3D-volumetric sequence. For MRI 2, it was only 25%; 47% of patients had a Smit sleeve implanted in MRI 2, while 53% did not, and 36% had Gadolinium contrast in MRI 2, while 64% had none. The patient characteristics are listed in Table 1.  
The EBRT began, on average, 51 days after histological proof of diagnosis (range 11 to 145 days). The volume of the CTV in MRI 1 was an average of 48 cm\({}^{3}\) (range 17 to 223 cm\({}^{3}\)); in MRI 2, it was 34 cm\({}^{3}\) (range 7 to 104 cm\({}^{3}\)). The decrease in CTV thus amounted to an average of 28% (range 9% progression to 75% remission of CTV) after a previously administered dose of an average of 41.96 Gy (range 12 Gy to 50 Gy, depending on the elapsed time from beginning of EBRT to MRI 2). The CTV for the IGABT in the CT was, on average, 51 cm\({}^{3}\) (range 9 to 134 cm\({}^{3}\)). The volume of the intersection between MRI 2 and  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Patient Properties** & \\ \hline Number of Patients & 53 \\ \hline Adaptive MRI available & 47 \\ \hline Age & mean 52 Y \\  & min. 29 Y \\  & max. 80 Y \\ \hline  & 18.9\% cT1 \\ Tumor size TNM & 45.3\% cT2 \\  & 28.3\% cT3 \\  & 7.5\% cT4 \\ \hline Pelvic lymph node metastasis & 34\% N0 \\  & 66\% N1 \\ \hline Distant lymph node metastasis & 73.6\% no \\  & 26.4\% yes \\ \hline  & 0\% G1 \\ Grading & 51\% G2 \\  & 49\% G3 \\ \hline Lymphatic vessel invasion & 9.4\% L1 \\  & 90.6\% L0 \\ \hline Blood vessel invasion & 86.8\% V0 \\  & 13.2\% V1 \\ \hline  & 86.8\% squamous \\ Differentiation & 9.4\% Adenocarcinoma \\  & 3.8\% small cell or adeno-squamous \\ \hline \hline \end{tabular}
\end{table}
Table 1: Patient characteristics.  
the CT was, on average, 28 cm\({}^{3}\) (range 4 to 88 cm\({}^{3}\)). The intersection covered an average of only 80.8% of the CTV in MRI 2 (range 39 to 100%). In other words: if the IGABT had been performed after planning in MRI 2 only, 19.2% of the tumor would have been missed by IGABT. In the group of patients with a sleeve implanted, the intersection covered an average of 84% of the CTV in MRI 2; without the sleeve, it was 78%. The coverage in the group of patients with a 3D-volumetric MRI 2 was 79%. In patients with the Gadolinium contrast agent during MRI 2, the coverage was 78% (variance 161, standard deviation 13).  
The CTV was, on average, 72% larger in the CT than it was in MRI 2. Taken the other way, an average of 53% of the CTV in the CT was covered by intersection with MRI 2 (range 19 to 87%). In patients with a sleeve, an average of 52% was covered; for without a sleeve, an average of 53% was covered. Likewise, with a 3D-volumetric MRI 2, it was 57% covered, and with a contrast medium in the MRI 2, it was 58% covered.