Takahiro Otani

Diffusion changes in a tumor and peritumoral tissue after stereotactic irradiation for brain tumors: possible prediction of treatment response.

Objective: Changes in apparent diffusion coefficient (ADC) in a tumor and peritumoral tissue after stereotactic irradiation (STI) were evaluated, and then the therapeutic efficacy of ADC measurement was assessed. Methods: In 20 tumors, diffusion-weighted imaging within 1 week before and 2-4 weeks after STI was performed. The normalized ADC (nADC) was measured. The nADCs in the tumor and peritumoral region before STI were compared with those after STI and the change in tumor nADC compared with the change in tumor size. Results: The nADC of the tumors was significantly higher 2-4 weeks after STI compared with that before STI. The nADC of the peritumoral regions 2-4 weeks after STI did not differ significantly from that before STI. A significant difference in the nADC at 2-4 weeks after STI was observed between the responder and nonresponder groups. Conclusions: Changes in nADC as measured by diffusion-weighted imaging can predict response to STI.

Craniocervical junction venous anatomy around the suboccipital cavernous sinus: evaluation by MR imaging

The present study evaluated the venous anatomy of the craniocervical junction, focusing on the suboccipital cavernous sinus (SCS), a vertebral venous plexus surrounding the horizontal portion of the vertebral artery at the skull base. MR imaging was reviewed to clarify the venous anatomy of the SCS in 33 patients. Multiplanar reconstruction MR images were obtained using contrast-enhanced three-dimensional fast spoiled gradient–recalled acquisition in the steady state (3-D fast SPGR) with fat suppression. Connections with the SCS were evaluated for the following venous structures: anterior condylar vein (ACV); posterior condylar vein (PCV); lateral condylar vein (LCV); vertebral artery venous plexus (VAVP); and anterior internal vertebral venous plexus (AVVP). The SCS connected with the ACV superomedially, with the VAVP inferolaterally, and with the AVVP medially. The LCV connected with the external orifice of the ACV and superoanterior aspect of the SCS. The PCV connected with the posteromedial aspect of the jugular bulb and superoposterior aspect of the SCS. The findings of craniocervical junction venography performed in eight patients corresponded with those on MR imaging, other than with regard to the PCV. Contrast-enhanced 3-D fast SPGR allows visualization of the detailed anatomy of these venous structures, and this technique facilitates interventions and description of pathologies occurring in this area.

Reduced perfusion reserve in Leukoaraiosis demonstrated using acetazolamide challenge 123I-IMP SPECT.

Objective: We examined the relationship between the perfusion reserve as measured by acetazolamide (ACZ)-challenge N-isopropyl-I-123-p-iodoamphetamine (IMP)-single-photon emission computed tomography (SPECT) and the degree of leukoaraiosis (LA) as estimated using magnetic resonance imaging. Methods: In 51 patients receiving 123IMP-SPECT with the resting state and ACZ challenge, the unaffected cerebral hemispheres were included in the present study. Mean cerebral blood flow (CBF) in the resting state and ACZ reactivity were acquired. Absolute CBF value and ACZ reactivity were compared among patients with LA grades 0, 1, and 2. The relationship between mean age and LA grade was also assessed. Results: No significant difference in the absolute CBF value in the resting state was observed among the 3 LA groups. Although vasoreactivity in LA grade 0 did not differ from that in grade 1, vasoreactivity in LA grade 2 was significantly lower (P < 0.05) than that in grades 0 or 1. Conclusions: The perfusion reserve is impaired in advanced LA.

Image fusion of thallium-201 SPECT and MR imaging for the assessment of recurrent head and neck tumors following flap reconstructive surgery

The aim of this study was to assess the value of fused MR and Tl-201 single photon emission computed tomography (SPECT) images in the diagnosis of recurrent head and neck tumors in patients after flap reconstruction surgery. Twenty-four patients after resection of primary head and neck tumors with flap reconstruction were suspected of having recurrent tumor by follow-up MR examination. Both MR examination and Tl-201 SPECT were prospectively performed to produce fused images. For qualitative analysis, two independent readers separately evaluated the existence of tumor recurrence in the fused images. The Tl-201 uptake of the lesion (Tl index) was also quantitatively compared with that of the normal nuchal muscles. Eighteen patients were histologically proved as having recurrence. The remaining 6 patients, false positive on MRI alone, had non-recurrence. Using the fused images, false positive was found in 1 case for one reader and 2 cases for the other reader. The Tl index of recurrent tumors was significantly higher (p<0.001) than that of non-recurrent mass lesions. In the assessment of recurrent tumors following flap reconstruction surgery in the head and neck, the use of fused MRI and Tl-201 SPECT images can reduce the number of false positives.

Correlation between severity of carotid stenosis and vascular reserve measured by acetazolamide brain perfusion single photon emission computed tomography.

Few studies have investigated the relationship between the degree of stenosis of the internal carotid artery (ICA) and cerebrovascular reserve (CVR). This study examined that relationship. A total of 56 ICAs in 43 patients were included. Computed tomography scan or magnetic resonance imaging showed no evidence of infarction in any of these patients. Both iodine-123-N-isopropyl-p-iodoamphetamine ((123)IMP)-single photon emission computed tomography (SPECT) in the resting state and (123)IMP-SPECT with acetazolamide (ACZ) enhancement were performed. Quantitated cerebral blood flow (CBF) images were acquired with the (123)IMP autoradiography technique. The mean CBF without ACZ administration (resting CBF) and CVR in the middle cerebral artery territory were calculated using stereotactic extraction estimation (SEE) analysis software. The degree of stenosis in the origin of the ICA was calculated from intra-arterial digital subtraction angiography. Resting CBF was not correlated with the degree of ICA stenosis; however, nonlinear regression analysis (second-order equation) showed a moderate correlation between CVR and the degree of ICA stenosis. In 72% of the cases with a CVR <30%, ICA stenosis was >74%. Using the SEE method, CVR was moderately correlated with the degree of ICA stenosis. Our findings indicate that evaluating CVR by ACZ-enhanced (123)IMP-SPECT in patients with ICA stenosis is of clinical value.

Contrast-Enhanced Multi-Shot Echo-Planar FLAIR in the Depiction of Metastatic Tumors of the Brain: Comparison with Contrast-Enhanced Spin-Echo T1-Weighted Imaging

Background: The usefulness of fast fluid-attenuated inversion-recovery (FLAIR) sequences after administration of contrast medium (f-FLAIR (+)) has been shown in depicting brain tumors including metastases and meningeal carcinomatosis. Contrast-enhanced multi-shot echo-planar FLAIR (Ms-EPI-FLAIR (+)), comprising combined sequences of f-FLAIR (+) and Ms-EPI, may provide the advantages of f-FLAIR (+) along with rapid acquisition. Purpose: To compare Ms-EPI-FLAIR (+) with post-contrast spin-echo T1-weighted imaging (SE-T1WI (+)) in the depiction of brain metastases. Material and Methods: In 14 patients with metastatic tumors of the brain, spin-echo precontrast T1-weighted imaging (SE-T1WI (−)), fast spin-echo T2-weighted imaging (FSE-T2WI), fast-FLAIR, SE-T1WI (+), and Ms-EPI-FLAIR (+) were acquired. For qualitative evaluation of SE-T1WI (+) and Ms-EPI-FLAIR (+), receiver operating characteristic (ROC) analysis was performed in two different readers. For quantitative analysis, the intensity ratios (intensity of tumor divided by intensity of peritumoral region) in SE-T1WI (+) and Ms-EPI-FLAIR (+) were compared. Results: Although pre-contrast f-FLAIR detected 84 of 106 tumors, Ms-EPI-FLAIR (+) detected 98 of 106 tumors. In the ROC analysis for observers A and B, Az values in SE-T1WI (+) did not differ from values in Ms-EPI-FLAIR (+). Quantitatively, the intensity ratio in Ms-EPI-FLAIR (+) also did not differ from that in SE-T1WI (+). Conclusion: Detectability of brain metastases with Ms-EPI-FLAIR (+) is almost similar to that with SE-T1WI (+). Ms-EPI-FLAIR (+) could be an alternative to SE-T1WI (+) in the depiction of brain metastases.

Evaluation of Postoperative Status after Clipping Surgery in Patients with Cerebral Aneurysm on 3‐Dimensional‐CT Angiography with Elimination of Clips

The use of 3‐dimensional computed tomography angiography (3D‐CTA) for clipped aneurysms is limited. Usefulness of 3D‐CTA with elimination of bone and clips was evaluated in patients with clipped cerebral aneurysms.

Spinal hyperostosis as an important sign indicating spine injuries on postmortem computed tomography

Although spine injuries are not always detectable on postmortem computed tomography (PMCT), spinal hyperostosis, an important risk factor for spine injury, is relatively easily detectable on PMCT. We therefore examined the utility of the detection of spinal hyperostosis on PMCT as an indicator of spine injury. Full-body PMCT images of 88 autopsy cases with a bruise on the face or forehead but no identifiable skull fracture were reviewed prior to autopsy for the identification and classification of spinal hyperostosis. Spine injuries were observed in 56.0% of cases with spinal hyperostosis and 1.6% of cases without spinal hyperostosis. Among the cases with spinal hyperostosis, spine injuries were observed in 66.7% of cases at stage 2 or 3 and in 88.9% of cases at stage 3. Spine injuries were diagnosed on PMCT in 33.3% of cases prior to autopsy. A significant association was found between spinal hyperostosis and presence of spine injury that cannot be detected on PMCT, indicating that the identification of spinal hyperostosis on PMCT may assist in detecting spine injuries. This finding suggests that investigation of the presence of spine injury based on the identification of spinal hyperostosis on PMCT may assist in determining the correct cause of death by autopsy.

Comparison of201Tl-chloride SPECT with99mTc-MIBI SPECT in the depiction of malignant head and neck tumors

ObjectiveComparison of201T1 chloride SPECT (Tl-SPECT) with99mTc-MIBI SPECT (MIBI-SPECT) in the depiction of malignant head and neck tumors was prospectively studied.MethodsForty-one patients with various tumors of the head and neck were included in this prospective study. Histologically, 36 patients had squamous cell carcinomas, 3 undifferentiated carcinomas, 1 transitional cell carcinoma, and 1 MALT lymphoma. All patients underwent a simultaneous dual-isotope SPECT of the head and neck with201Tl and99mTc-MIBI. Dual-isotope SPECT for early (n = 41) and delayed acquisition (n = 21) was performed. Qualitatively, 3 observers evaluated both Tl-SPECT and MIBI-SPECT individually. The interpretation criteria were graded as grade 1 (no abnormal increased uptake) to 5 (definitely increased uptake of a degree equal to or greater than that of normal salivary gland). Statistical analysis of the comparison of Tl-SPECT and MIBI-SPECT was performed. The interobserver difference was evaluated using the κ-coefficient. Quantitatively, T/N ratio (the ratio of the counts in the tumor divided by that in the normal nuchal muscles) and retention index were compared between Tl-SPECT and MIBI-SPECT.ResultsOn both the early and delayed images, the grades of uptake of the tumor in Tl-SPECT were significantly higher than those in MIBI-SPECT by three observers. The grade of T1-uptake of the tumor on the delayed images was 5 for all observers (κ-coefficient =1); however, the κ-coefficient varied from 0.39 to 0.84 in early Tl-SPECT, and in early and delayed MIBI-SPECT. Statistical differences in T/N ratio were noted between early Tl-SPECT (2.87 ± 1.19) and MIBI-SPECT (2.48 ± 1.06), and between delayed Tl-SPECT (2.11 ± 0.70) and MIBI-SPECT ( 1.20 ± 0.48). The retention index of Tl-SPECT (0.81 ± 0.24) was significantly higher than that of MIBI-SPECT (0.52 ± 0.15).ConclusionsThe present study qualitatively and quantitatively showed that201T1 had higher accumulation in the tumor than99mTc-MIBI in both early and delayed images.

Contrast-enhanced 3D FIESTA imaging in Tolosa-Hunt syndrome.

(Headache 2012;52:822‐824)