The 31 year-old former European champion hurt Lodjanidze with some crunching body shots before taking him out and keeping his unbeaten run intact.
Helenius could now make a move towards the bigger fights in the division after successfully fending off a string of injuries and question marks over his career.
In France, Carlos Takam halted Briton Michael Sprott in the fifth round to record back-to-back wins since his loss to Alexander Povetkin.
Sprott, 40, informed WBN he was unhappy that the fight ended when it did and said with adequate time to prepare it may have been a different story.
“The ref decided to stop it in round five and I respect his decision, but I thought I was fine,” Sprott told World Boxing News.
“I think I did okay since I only had two weeks to get ready with not much training. If I had six weeks in camp I would really have beat him as he would found my jab too much.”
Elsewhere in Italy, southpaw Cedric Vitu ended the undefeated run of Orlando Fiordigiglio in the eleveth round to pick up the European super welterweight title. Vitu, 29, pushed his own C.V to 42-2, whilst Fiordigiglio dropped to 20-1 with his first loss.
