Study design
This was a prospective study. This study was approved by the ethics committee.
We recruited 19 AIDS patients from October 2018 to February 2020 who underwent multimodal MR. All patients were divided into two groups: AR-PCNSL group (9 cases) and infection group (10 cases) by pathological results. The multimodal MR imaging features of the patients were summarized. We will analysis whether multimodal MR data is helpful for the diagnosis of AR-PCNSL.
Participants
All AIDS diagnosis was conformed to the “Chinese guidelines for AIDS Diagnosis and Treatment (2015)” [
16]. The criteria required a serologic and Western blot confirmation. If WB was not positive, double HIV-RNA (Ribonucleic acid) positive could confirm the diagnosis.
The time from onset of symptoms to MR examination in the AR-PCNSL group was 10–120 days, with a mean of 57.8 days. Patients’ age ranged from 25 to 52 years, with a mean of 37.9. There were seven males and two females. The time from onset of symptoms to MR examination in the infection group was 1–120 days, with a mean of 40.8 days. In this group, patients’ age ranged from 24 to 52 years, with a mean of 34.1 years. There were nine males and one female. The clinical symptoms lacked of specificity. The most common was fever (nine cases, 47.4%), followed by headache/dizziness (six cases, 31.6%), hemiparesis (four cases, 21.1%), vision loss (three cases, 15.8%) and transient loss of consciousness (two cases, 10.5%).
The pathology results of the AR-PCNSL group were as follows: nine cases were B-cell lymphoma, including six cases of diffuse large B-cell lymphoma, one case of Burkitt lymphoma, and two cases of highly invasive B-cell lymphoma. Of the nine cases, seven cases were positive for EBV nucleic acid (using a probe for EBV-encoded small RNA (EBER)) in biopsy material, one case was negative and the other one was not tested.
Biopsies were carried out in infection group who were failure to empiric antibiotics for toxoplasmosis and tuberculosis. All 10 cases were confirmed by pathology. There were three cases of toxoplasmosis, four cases of PML, one case of tuberculoma (positive for acid-fast pus), and one case of brain abscess. Inflammatory/infectious changes were reported in one case, but the aetiology was unknown.
The inclusion criteria were as follows: inpatients who met the diagnostic criteria of the “Chinese guidelines for AIDS Diagnosis and Treatment (2015)” [
16] and patients with central neuropathy. The patients who agreed to perform multimodal MR scanning and signed the informed consent form.
The exclusion criteria were as follows: patients with contraindications to MR examination; patients who had metal implants, and patients who did not agree to multimodal MR. AIDS patients with other brain tumors or did not have pathological results.
Imaging examination
GE Discovery MR750W 3.0 T was used for MR examination. Multidirectional (axial, sagittal, coronal) scanning and multiparameter scanning were performed, including conventional MR T1WI, T2WI and enhanced examination. The contrast agent meglumine gadolinium (Magnevist, Bayer AG, Germany) was injected through the elbow vein or the dorsal hand vein (20 ml for each patient); with an injection flow rate of 1.5–2.0 ml/s. Multimodal MR included 3D-pCASL, DWI and SWI sequences. The DWI sequence parameters were: TR 4880 ms, TE 77.4 ms, b = 1000, matrix 256 × 256, FOV 240 mm × 240 mm; 3D-pCASL: TR 4852 ms, TE 10.7 ms, matrix 128 × 128, FOV 240 mm × 240 mm, PLD 1.5 s delay; SWI: TR 77.6 ms, TE 42.56 ms, matrix 512 × 512, FOV 240 mm × 240 mm.
Image analysis
Two deputy chief physicians performed blind evaluations of the conventional and multimodal MR images. They reached a consensus through further discussion when their opinions differed. The location, number, distribution and enhancement of the lesions were observed by conventional MR.
Multimodal MR analysis: All the original data were imported into a GE MR ADW4.6 workstation for correction and noise reduction. The DWI/ADC and cerebral blood flow (CBF) obtained in the solid, maximum blood perfusion area and the ADC/CBF values of the tumor body were the most stable, and areas of cystic degeneration, hemorrhage, large vessels and artifacts were avoided.
The ratio of CBF and ADC was obtained by measuring the fixed area and setting the control in the contralateral normal brain area. SWI image processing adopted the degree of ITSS [
17], which was specifically referring to the thin line-like or dot-like structures with low signal intensity in lesions. The degree of ITSS was divided into 4 grades: grade 0, no ITSS; grade one, 1–5 dotlike or fine linear ITSSs; grade two, 6–10 dotlike or fine linear ITSSs; and grade 3, ≥11 dotlike or fine linear ITSSs in the continuous area within a tumor [
17]. Due to the small number of cases in this study, SWI-ITSS 0–1 and ITSS 2–3 were discussed in combination.
Statistical methods
Statistical Product and Service Solutions (SPSS) 19.0 statistical software was used for routine analysis between two groups. The conventional MR and multimodal MR imaging findings were analyzed by Fisher’s method because the number of cases was less than 40. Statistically significant differences were defined as p < 0.05. The diagnostic sensitivity, specificity, and total consistent rate of AR-PCNSL were calculated for conventional MR and conventional MR combined with DWI-ADC/SWI-ITSS.