Application of PET/MRI in Gynecologic Malignancies

Abstract

The diagnosis, treatment, and management of gynecologic malignancies benefit from both positron emission tomography/computed tomography (PET/CT) and MRI. PET/CT provides important information on the local extent of disease as well as diffuse metastatic involvement. MRI offers soft tissue delineation and loco-regional disease involvement. The combination of these two technologies is key in diagnosis, treatment planning, and evaluating treatment response in gynecological malignancies. This review aims to assess the performance of PET/MRI in gynecologic cancer patients and outlines the technical challenges and clinical advantages of PET/MR systems when specifically applied to gynecologic malignancies.

Keywords: PET/MRI; cervical cancer; endometrial cancer; gynecological malignancy; ovarian cancer; vaginal cancer.

Figure 1

A 49-year-old woman with stage IVB cervical cancer. Both the coronal T2-weighted image (a) and fused PET/MRI (d) demonstrate the tumor with parametrial involvement and almost the entire vaginal vault (white arrows in (a,d)). There is also involvement of the bladder, ovaries, and proximal ureters (not imaged). Bilateral hydronephrosis is partially visualized (red arrows in (a) and (d)). The mass demonstrates diffusion restriction on the ADC map (arrow in (b)) and bright signal on the DWI (arrow in (e)). Axial Dixon water MRI (c) and axial-fused PET/MRI (f) show lung metastasis (arrows). Liver metastasis (arrows) and additional lung metastasis (arrowhead) are demonstrated in axial Dixon in-phase MRI (g) with high FDG uptakes on axial-fused PET/MRI (h). (Courtesy of Elisabeth Hedlund, MD, Håkan Ahlström, MD, and Björg Jónsdóttir, MD, PhD, Uppsala University, Uppsala, Sweden).

Figure 2

A 43-year-old woman with stage IB1 cervical cancer found to have a corpus luteum cyst in her right ovary. The cyst is visualized as a peripherally low-intensity structure with central high intensity (arrow in (b)) on ADC map and a peripherally hyperintense structure with low central intensity (arrow in (c)) on the axial diffusion-weighted image. The corresponding FDG uptake (arrow in (f)) on the fused PET/MRI is determined to be benign. In addition, the benign ovarian cyst in the left ovary is seen (star in (a)) with no pathological FDG uptake. The arrowhead in (a,b,f) shows part of the left superior corner of the bladder with corresponding FDG uptake in the urine. Sagittal T2-weighted MRI (d) and sagittal-fused PET/MRI (e) show the cervical mass (arrow in (d,e)). (Courtesy of Elisabeth Hedlund, MD, Håkan Ahlström, MD, and Björg Jónsdóttir, MD, PhD, Uppsala University, Uppsala, Sweden).

Figure 3

A 22-year-old woman with stage IB2 cervical cancer clinically or stage IIIC1 cancer as determined via PET/MRI due to a metastatic lymph node. The metastatic lymph node (arrow) is hypointense on the axial T2-weighted MRI (a); low signal on the ADC map (b); high signal on the DWI (c), with FDG uptake on fused PET/MRI (d) images. Physiologic FDG uptake in bladder (arrowheads in (d)) and endometrium (red arrow in (d)) can be seen. Both axial T2-wighted MRI (e) and axial-fused PET/MRI (f) show the cervical tumor with a suspicious irregular right margin (arrow in (e)) with pathologic FDG uptake interpreted as parametrial invasion (arrow in (f)). (Courtesy of Elisabeth Hedlund, MD, Håkan Ahlström, MD, and Björg Jónsdóttir, MD, PhD, Uppsala University, Uppsala, Sweden).

Figure 4

A 54-year-old woman with squamous cell carcinoma of the cervix, FIGO stage IVA. Sagittal T2-weighted MRI (a) shows a 43 mm tumor (star) with indications of invasion into the upper vagina and bladder (arrow) with suspected vesicovaginal fistula (arrowhead). Sagittal-fused PET/MRI (b) shows the FDG uptake of the tumor (star) and bladder wall (arrow). Both axial T2-weighted image (c) and axial-fused PET/MRI (d) demonstrate an 8 mm lymph node with irregular margins and pathologic FDG uptake (arrow in (c,d)). On axial-fused PET/MRI, (d) there is pathologic FDG uptake corresponding to the cervical tumor (star in (d)), which is difficult to distinguish on the axial T2-weighted image. Physiological FDG uptake in the bowel is seen on axial-fused PET/MRI (arrowhead in (d)). (Courtesy of Elisabeth Hedlund, MD, Håkan Ahlström, MD, and Björg Jónsdóttir, MD, PhD, Uppsala University, Uppsala, Sweden).

Figure 5

An 81-year-old woman with high-grade serous carcinoma of an endometrial origin. FDG PET/MRI was obtained for staging. Axial-focused PET image (d) demonstrating focal intense FDG uptake within the lower uterus and upper cervix, corresponding to a hypoenhancing mass seen on the axial T1-weighted post-contrast image (a). Additionally, an 8 mm short axis left common iliac chain node with mild FDG uptake was noted (b,e). There was no evidence of more distant metastatic disease. The patient was treated with pelvic radiation including boost to the left iliac chain lymph node, and subsequent chemotherapy. Follow-up axial T1-weighted image (c) and PET/MR (f) revealing complete metabolic response with absent FDG uptake within the mass, and complete resolution of abnormal enhancement with only a small amount of non-enhancing fluid in the endometrial canal. (Courtesy of Eric C. Ehman, MD, Department of Radiology, Mayo Clinic, Rochester, MN, USA).

Figure 6

A 68-year-old female’s history of stage IVb endometrioid endometrial cancer who underwent systemic therapy, hysterectomy, and bilateral salpingo-oophorectomy with recurrent disease and pelvic implants in the vaginal cuff. Axial oblique small FOV T2-weighted (a) and axial post-contrast T1-weighted fat-saturated images (b) show two T2 intermediate signals, heterogeneously enhancing pelvic implants in the vaginal cuff (arrow and arrowhead). Fused PET/CT (c) images show intense FDG uptake in the pelvic implants (arrow and arrowhead). After external beam radiation therapy and brachytherapy, axial oblique small FOV T2-weighted (d) and axial post contrast T1-weighted fat-saturated images (e) show a decrease in size and the enhancement of the two pelvic implants in the vaginal cuff (arrow and arrowhead). Fused PET/MRI images (f) show a decrease in FDG uptake in the pelvic implants (arrow and arrowhead) with the small residual rim of a viable tumor, compatible with the partial local treatment response. (g) The axial in-phase image of the chest shows three new pulmonary nodules, most likely metastasis (arrowheads). A fused PET/MRI image (h) shows FDG uptake in the pulmonary nodules (arrowheads). (i) An axial post-contrast T1-weighted fat-saturated image shows a new heterogeneously enhancing metastatic liver mass with focal intense FDG uptake on fused PET/MRI images (arrowhead in (j)). (Courtesy of Vipul Sheth, MD, PhD and Negaur Iranpour, MD, Department of Radiology, Stanford University, Stanford, CA, USA).

Figure 7

A 50-year-old female patient with peritoneal carcinomatosis secondary to ovarian clear cell carcinoma has a surgical peritoneal cancer index (PCI) score of 14 and a minimal amount of free fluid. On an axial T2-weighted image (a), a large cystic mass (hyperintense lesion) with a solid component appears slightly hypointense (arrow on (a)), shows restricted diffusion on the DWI and ADC map (arrows on (g,d)), and has high FDG uptake on fused PET/MRI (arrow in (j)). A 5 mm lymph node near the right internal iliac vessels is visibly hypointense on T2WI (arrow on (b)), shows restricted diffusion on DWI and ADC map (arrows in (h,e)), and has high FDG uptake (arrow on (k)). Notably, there is a peritoneal implant in the dorsal right liver lobe (arrows in (c,f,i,l)). (Courtesy of Elisabeth Hedlund, MD, Håkan Ahlström, MD, and Björg Jónsdóttir, MD, PhD, Uppsala University, Uppsala, Sweden).

Figure 8

A 43-year-old woman with peritoneal carcinomatosis secondary to high-grade serous carcinoma has a surgical PCI score of 22. On an axial T2-weighted image, the bilateral ovarian tumors appear moderately hypointense (arrows in (a)) and show uptake of FDG on fused PET/MRI (arrows in (d)). Large omental caking ventral to the uterus and ovaries is also visible (arrowheads on (a,d)). Spread of the peritoneal implant to the left the paracolic gutter (in the lower abdomen (arrows in (b,e)) and the medial border of the right liver lobe can be observed (arrows in (c,f)) (Courtesy of Elisabeth Hedlund, MD, Håkan Ahlström, MD, and Björg Jónsdóttir, MD, PhD, Uppsala University, Uppsala, Sweden).

Figure 9

A 63-year-old woman with peritoneal carcinomatosis secondary to bilateral high-grade serous carcinoma with a PCI score of 39 with invasion of the rectal wall (arrowhead in (a,d)). On axial T2-weighted images, massive infiltration of the greater omentum is visible (arrows in (a,b)) with high FDG uptake (arrows in (d,e)) on axial-fused PET/MRI images. Both axial T1-weighted in-phase (c) and axial-fused PET/MRI (f) demonstrate multiple peritoneal implants spread across the surface of the liver, carcinomatosis implants on the diaphragm (arrows in (c,f)), and one supradiaphragmatic lymph node metastasis (arrowhead in (c,f)). (Courtesy of Elisabeth Hedlund, MD, Håkan Ahlström, MD, and Björg Jónsdóttir, MD, PhD, Uppsala University, Uppsala, Sweden).

Figure 10

A 64-year-old woman with history of vulvar cancer diagnosed 4 years prior and initially treated with left vulvectomy. The patient was re-evaluated due to new symptoms of pain and itching, and a biopsy was performed, revealing a recurrent high-grade squamous neoplasm. PET/MRI was ordered for restaging. Axial PET (b) and T2-weighted (a) images from dedicated pelvis MRI with dedicated pelvic PET show an FDG-avid, nodular, intermediate T2 signal in the left perineum compatible with local recurrence. The whole-body survey MIP image (c) and axial-fused PET/MRI images (d,e) demonstrate bilateral FDG-avid inguinal lymph nodes without more distant metastatic disease. The patient went on to undergoing wide local excision with adjuvant radiation and chemotherapy. (Courtesy of Eric C. Ehman, MD, Department of Radiology, Mayo Clinic, Rochester, MN, USA).