Clinical indications: what is the evidence?

By performing a systematic review and meta-analysis, the diagnostic value of ¹⁸F-FDG PET/MRI in breast lesions, lymph nodes, and distant metastases was assessed, and the merits and demerits of PET/MRI in the application of breast cancer were comprehensively reviewed.

Breast cancer-related studies using ¹⁸F-FDG PET/MRI as a diagnostic tool published before September 12, 2022 were included. The pooled sensitivity, specificity, log diagnostic odds ratio (LDOR), and area under the curve (AUC) were calculated using Bayesian bivariate meta-analysis in a lesion-based and patient-based manner.

We ultimately included 24 studies (including 1723 patients). Whether on a lesion-based or patient-based analysis, PET/MRI showed superior overall pooled sensitivity (0.95 [95% CI: 0.92-0.98] & 0.93 [95% CI: 0.88-0.98]), specificity (0.94 [95% CI: 0.90-0.97] & 0.94 [95% CI: 0.92-0.97]), LDOR (5.79 [95% CI: 4.95-6.86] & 5.64 [95% CI: 4.58-7.03]) and AUC (0.98 [95% CI: 0.94-0.99] & 0.98[95% CI: 0.92-0.99]) for diagnostic applications in breast cancer. In the specific subgroup analysis, PET/MRI had high pooled sensitivity and specificity for the diagnosis of breast lesions and distant metastatic lesions and was especially excellent for bone lesions. PET/MRI performed poorly for diagnosing axillary lymph nodes but was better than for lymph nodes at other sites (pooled sensitivity, specificity, LDOR, AUC: 0.86 vs. 0.58, 0.90 vs. 0.82, 4.09 vs. 1.98, 0.89 vs. 0.84).

¹⁸F-FDG PET/MRI performed excellently in diagnosing breast lesions and distant metastases. It can be applied to the initial diagnosis of suspicious breast lesions, accurate staging of breast cancer patients, and accurate restaging of patients with suspected recurrence.

To examine the contribution of magnetic resonance imaging (MRI) to characterise palpable breast masses after conventional imaging was found to be non-contributory.

The breast MRI database was reviewed for studies performed between January 2010 and December 2015 for the clinical indication of palpable breast finding with negative standard imaging. Medical files were reviewed for demographic data, clinical information, radiology, and pathology reports. Benign versus malignant outcomes were determined at histopathology or a minimum of 12 month follow-up.

Investigation of palpable breast finding was the clinical indication for 167 of 7,782 (2%) examinations. Thirty-two (19%) women in the study had positive MRI findings. Most (20, 63%) findings corresponded to the palpable area, resulting in three carcinomas being diagnosed. Only one carcinoma required MRI-guided biopsy for diagnosis. Eighteen women with negative MRI underwent ultrasound-guided biopsy from the palpable area, which resulted in a diagnosis of one carcinoma. One carcinoma was incidentally detected in another location. Within the present population, the sensitivity for detecting malignancy was 80%, specificity 78%, negative predictive value 99%, and positive predictive value 13%.

Although cancer was found in four cases in the palpable area, the biopsy was directed using MRI in only one case. A new palpable finding with non-contributory standard imaging should prompt a needle-guided biopsy and not further evaluation using MRI.