Pyogenic spondylodiscitis (PS) is the most commonly encountered spine infection. Common causative bacteria are Staphylococcus aureus (up to 60%) followed by Enterobacter (up to 30%), Streptococcus, Pseudomonas, Klebsiella and Salmonella. The course may be acute or chronic and the symptoms are non specific. Elevated ESR, PRC and WBC, are not constant laboratory findings. The primary radiologic finding is destruction of two contiguous vertebral bodies and the intervertebral disc. Plain radiographs are not sensitive in the early stages and become positive 2–4 weeks after onset of symptoms. Progressive osteolysis beneath the anterior endplate and loss of endplate definition, are signs highly suggesting PS (20). A rapid loss of the intervertebral space matched with loss of definition in the opposing endplate and associated osteolysis beneath it, suggest spread to the contiguous vertebral body. As a rule, the presence of gas (“vacuum” in the disc and “cleft” beneath the endplate), rules out infection. CT is more sensitive to earlier changes showing in addition to plain films effacement of paravertebral fat planes and contrast enhancement of paravertebral soft tissue changes. It may be useful when MRI findings are equivocal, by showing the presence of disc “vacuum” sign and the lack of endplate destruction which help to rule out infection. It offers in addition a guidance of the route for diagnostic aspiration. MRI is the method of choice for early detection and accurate diagnosis of PS. Low on T1-weighted and high on fluid sensitive sequences bone marrow edema initially, followed by loss of the “black” outline of the endplate cortex, are the acute phase imaging findings [20, 21]. Bone marrow edema is located underneath the disrupted endplate cortex. Later, high signal on fluid sensitive sequences is seen within the involved disc. Fat suppressed images following contrast medium administration, show enhancement of the bone marrow and the disc, excluding the necrotic areas [20, 21]. Occasionally, depending on the duration of symptoms, a paraspinal or intra-canalicular phlegmon may be seen. A peripheral rim enhancement corresponds to abscess formation, often in thoracic spine. Εpidural abscesses result in high morbidity and mortality and may be the initial feature of the disease from a remote underlying infection in cases of extension from facets and retroperitoneum or from hematogenous spread directly to this anatomic location. Subdural abscess is a rare and urgent disorder, suggested on MRI when the shape of the sac and the epidural fat are preserved. Major differential diagnosis of PS should include Modic type I endplate degenerative changes [20–22]. In favor of infection are the high signal of the disc and lack of the normal intranuclear cleft on T2-weighted images as well as presence of disc enhancement. Dialysis-associated destructive spondyloarthropathy, showing sharply demarcated endplate erosions and low T2 signal in the paraspinal lesions, should also be included in the differential diagnosis [20]. Paraspinal edema and enhancement may be seen in axial spondyloarthritis-related enthesopathy. Acute Schmorl’s node and aseptic spondylodiscitis, previously known as Andersson’s lesion in the context of axial spondylarthropathy, may simulate early infection. A useful sign of PS healing on MRI is the focal return of bone marrow fatty signal on T1-weighted images. However, MRI is not recommended for follow-up as it lags 4–8 weeks behind clinical and serologic improvement in successful treatment [20, 23]. Thus, persistent or worse MRI findings in patients with clinical improvement, do not suggest a failed treatment. Newer techniques, such as diffusion-weighted imaging may show increased diffusivity and drop in the ACD values in PS, often indistinguishable from malignancy [24] but helpful in differentiating infectious from degenerative changes in the endplates, the latter showing lower ADC values [25]. Radionuclide imaging is not currently used routinely as it is limited by false negative results, inability to detect soft tissue involvement and the fact that it remains abnormal during the normal healing phase after resolution of infection [26]. Indeed, it is reserved for cases that MRI findings are inconclusive, for depicting multiple foci and for patients with contraindication for MRI. FDG-PET/CT may be more accurate than MRI in low-grade spondylodiscitis and useful particularly when severe degenerative changes coexist [26].