{
 "serie": "s3_Axial_PD_FS",
 "n_imgs": 24,
 "s": 77.1,
 "respuesta": "**Series:** Axial PD fat‑suppressed, right ankle, 24 sampled slices, ordered from distal (midfoot/Chopart level) to proximal (supramalleolar tibia/fibula). Orientation as displayed: anterior up, posterior (Achilles) down, lateral (fibula/peroneals) on the image left, medial on the image right.\n\n**Findings**\n\n1. **Tibiotalar joint effusion / synovitis** – Fluid distending the anterior recess (anterior to the talar neck/dome, slices 14–19) and the posterior recess (posterior to the talus, slices 17–19), more than trace. Confidence: high.\n\n2. **Anterior talofibular ligament (ATFL) – chronic injury** – At the lateral gutter level (slices 16–18), between the anterior fibula and the lateral talar body, the ligament is not seen as a normal thin low‑signal band; instead there is irregular, heterogeneous intermediate/high signal with fluid tracking into the anterolateral gutter. Appearance most consistent with a chronic thickened/scarred or attenuated ATFL tear (post‑sprain), with anterolateral gutter synovitis. Confidence: medium.\n\n3. **Sinus tarsi / subtalar region** – Increased fluid‑like signal in the lateral sinus tarsi and along the posterior subtalar joint (slices 11–14), with heterogeneous signal replacing the normally suppressed fat of the sinus tarsi. Suggests sinus tarsi synovitis/scarring and subtalar effusion (chronic instability pattern). Confidence: medium.\n\n4. **Posteromedial tendons – FHL tenosynovial fluid** – Fluid around the flexor hallucis longus tendon in the posterior recess/posteromedial ankle (slices 17–20), communicating with the posterior joint recess. Mild FHL tenosynovitis vs decompression of joint fluid. Confidence: medium.\n\n5. **Peroneal tendons** – Small amount of fluid in the common peroneal sheath lateral/posterolateral to the distal fibula (slices 18–22); tendons themselves are intact in caliber and signal, no split or dislocation. Mild peroneal tenosynovitis. Confidence: medium‑low.\n\n6. **Deep posterior compartment – abnormal high signal (supramalleolar level)** – Slices 21–24 show a large, fairly homogeneous hyperintense area posterior/posteromedial to the distal tibia in the expected location of the flexor hallucis longus muscle belly and Kager's fat region, whereas surrounding subcutaneous fat is well suppressed. This could represent muscle edema (strain/denervation) or a fluid collection; regional fat‑suppression failure is a differential, but the focal nature and normal suppression elsewhere favor a true finding. Recommend correlation with non‑FS sequences. Confidence: low‑medium.\n\n7. **Talar dome** – Subtle focal high signal at the medial aspect of the talar dome/body (slices 15–16) raising the question of a small subchondral cyst or osteochondral lesion (common after inversion sprain). No overt cartilage defect confidently seen on this plane. Confidence: low; correlate with coronal/sagittal images.\n\n8. **Deltoid ligament** – Medial gutter ligaments appear intact but slightly thickened/heterogeneous (slices 16–18); no discrete tear. Confidence: low.\n\n**Structures that appear normal**\n- Achilles tendon: normal caliber and low signal throughout (slices 15–24); no paratendinitis, no retrocalcaneal bursitis.\n- Tibialis posterior and flexor digitorum longus tendons: normal.\n- Anterior compartment tendons (tibialis anterior, EHL, EDL): normal.\n- Bone marrow of calcaneus, cuboid, navicular, cuneiforms and metatarsal bases: no marrow edema or fracture. No fibular or tibial marrow edema.\n- Calcaneofibular ligament and posterior talofibular ligament: intact on the visible slices (PTFL well seen, normal striated appearance).\n- Plantar fascia and plantar soft tissues: unremarkable; plantar vessels normal.\n- No syndesmotic widening or tibiofibular ligament tear identified.\n\n**Impression**\n1. Chronic ATFL injury with anterolateral gutter synovitis and moderate tibiotalar effusion, consistent with post‑sprain chronic lateral ankle instability.\n2. Sinus tarsi synovitis/scarring with subtalar effusion.\n3. Mild FHL and peroneal tenosynovitis.\n4. Indeterminate hyperintensity in the deep posterior compartment (FHL muscle/Kager region) at the supramalleolar level – muscle edema vs collection vs artifact; correlate with other sequences.\n5. Possible small medial talar dome osteochondral lesion – low confidence, correlate with coronal/sagittal images."
}