Detection rate of PET/CT in patients with biochemical relapse of prostate cancer using [ 68 Ga]PSMA I&T and comparison with published data of [ 68 Ga]PSMA HBED-CC.

PURPOSE: To determine the detection rate of PET/CT in biochemical relapse of prostate cancer using [68 Ga]PSMA I&T and to compare it with published detection rates of [68 Ga]PSMA HBED-CC.

METHODS: We performed a retrospective analysis in 83 consecutive patients with documented biochemical relapse after prostatectomy. All patients underwent whole body [68 Ga]PSMA I&T PET/CT. PET/CT images were evaluated for presence of local recurrence, lymph node metastases, and distant metastases. Proportions of positive PET/CT results were calculated for six subgroups with increasing prostate specific antigen (PSA) levels (<0.5 ng/mL, 0.5 to <1.0 ng/mL, 1.0 to <2.0 ng/mL, 2.0 to <5.0 ng/mL, 5.0 to <10.0, ≥10.0 ng/mL). Detection rates of [68 Ga]PSMA I&T were statistically compared with published detection rates of [68 Ga]PSMA HBED-CC using exact Fisher's test.

RESULTS: Median PSA was 0.81 (range: 0.01 - 128) ng/mL. In 58/83 patients (70 %) at least one [68 Ga]PSMA I&T positive lesion was detected. Local recurrent cancer was present in 18 patients (22 %), lymph node metastases in 29 patients (35 %), and distant metastases in 15 patients (18 %). The tumor detection rate was positively correlated with PSA levels, resulting in detection rates of 52 % (<0.5 ng/mL), 55 % (0.5 to <1.0 ng/mL), 70 % (1.0 to <2.0 ng/mL), 93 % (2.0 to <5.0 ng/mL), 100 % (5.0 to <10.0 ng/mL), and 100 % (≥10.0 ng/mL). There was no significant difference between the detection rate of [68 Ga]PSMA I&T and published detection rates of [68 Ga]PSMA HBED-CC (all p>0.05).

CONCLUSIONS: [68 Ga]PSMA I&T PET/CT has high detection rates of recurrent prostate cancer that are comparable to [68 Ga]PSMA HBED-CC.