34 S. H. Eriksson et al. different patterns of HS have not been identified on in vivo MRI. HS can readily be identified on MRI. The cardinal signs of HS on MRI are increased hippocampal signal on T2-weighted images and hippocampal volume loss on T1- weighted images (Jackson et al., 1990). In addition there may be decreased T1 signal intensity and disruption of the internal structure of the hippocampus (Jackson et al., 1993). The sequences used routinely to identify HS are T1-weighted volume acquisition, T2-weighted, proton den- sity and fluid attenuation inversion recovery (FLAIR) se- quences covering the whole brain (ILAE Commission on Neuroimaging, 1998). The Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction (“PROPELLER”) sequence is an effective means of compensating for head motion dur- ing MRI scans (Pipe, 1999). The mode of acquisition with PROPELLER allows it to intrinsically compensate for both translational and rotational head movements during the scan. Images are averaged and artifacts are reduced further since part of the acquired data can be rejected if correlation measures indicate through-plane motion (Pipe, 1999). Sub- tle movement can occur even in cooperative subjects. Re- duction of motion artifacts has been shown using the PRO- PELLER sequence in both volunteers and patients (Forbes et al., 2001). The aim of the current report was to explore the PROPELLER image quality of the hippocampus com- pared to routine sequences, in patients with epilepsy and suspected HS. MATERIAL AND METHODS Scans were performed on a GE 3T Excite HD scanner. Four patients undergoing investigations for epilepsy surgery were scanned with the PROPELLER sequence using TR/TE 4000/114.8, FOV 22 × 22 cm, acquisition matrix 416 × 416 and slice thickness 2 mm (giving a voxel size of 0.53 × 0.53 × 2 mm). Scan time was 3 min and 20 s. To obtain coronal images perpendicular to the hippocampal long axis, scans were acquired with the head tilted forward since these scans could not be acquired obliquely. All patients also had routine scans, including T1-weighted volume sequence (TR/TE/TI 7/3/450, flip angle 20◦, FOV 24 × 18 cm, acquisition matrix 256 × 256, slice thickness 1.1 mm, giving a voxel size of 0.94 × 0.70 × 1.1mm), T2-weighted and proton density (TE1/TE2/TR 30/80/2000 FOV 24 × 18 cm, acquisi- tion matrix 256 × 192, slice thickness 5.0 mm, giving a voxel size of 0.94 × 0.94 × 5.0 mm) and FLAIR images (TE/TR/TI 144/11000/2250, FOV 24×24 cm, acquisition matrix 256 × 224, slice thickness 5.0 mm, giving a voxel size of 0.94 × 1.1 × 5.0 mm). T1-volume scan time was 7 min and 11 s, T2 scan time was 3 min and FLAIR scan time was 2 min and 57 s. All patients had HS diagnosed on routine scans. Clinical details are listed in Table 1. The patients underwent a standard anterior temporal lobe resection. The hippocampal specimen was fixed for 1–3 days in 10% formalin and sectioned perpendicular to the long axis. Standard laboratory protocols were used to Table 1. Clinical data Patient 2 10 22 12 1 FC CPS: 4/month R temp epileptiform discharges; occasional brief gen spike wave episodes R temp rhythmic theta activity R HS Seizure-free Patient 3 1 43 42 1 prolonged FC CPS: 2–12/month, SGTCS: 10/year Independent bitemp epileptiform discharges Bilat theta with temporal emphasis L HS Seizure-free Patient 4 7 20 13 1 prolonged FC SPS: 15–20/ month L temp epileptiform discharges and theta activity L temp rhythmic theta activity L HS Seizure-free Patient 1 Age at onset (years) 7 Age at operation 23 (years) Duration of epilepsy 16 (years) Precipitating factors – for epilepsy Seizure types CPS: 4/month Inter ictal EEG ﬁndings Ictal EEG ﬁndings MRI ﬁndings Outcome∗ L temp epileptiform discharges; occasionally bilat. theta activity Evolving rhythmic theta activity L temp L HS Seizure-free Epilepsia, 49(1):33–39, 2008 doi: 10.1111/j.1528-1167.2007.01277.x FC, febrile convulsion; CPS, complex partial seizures; SGTCS, secondary generalized tonic–clonic seizure; SPS, simple partial seizures; L, left; R, right; temp, temporal; gen, generalized; ∗ seizure outcome at most recent follow up, between 6 and 12 months after surgery.