Prediction of the difficulty of proximal vascular control using 3D-CTA for the surgical clipping of internal carotid artery-posterior communicating artery aneurysms.

OBJECTIVE: During surgical clipping of internal carotid artery (ICA)-posterior communicating artery (PCoA) aneurysms, proximal vascular control (PVC) is difficult to achieve in some cases because of variations in the anatomy of this type of aneurysm and its parent arteries. The authors investigated morphometric features that may be predictive for the necessity of anterior clinoidectomy (ACL) or cervical ICA exposure for PVC. METHODS: The authors retrospectively reviewed 65 patients with an ICA-PCoA aneurysm treated with clipping during the previous 3 years. The factors considered for assessing the difficulty of attaining PVC included the following: the maximum diameter of the aneurysm; the distance between the tip of the anterior clinoid process (ACP) and the proximal aneurysmal neck; the presence of calcification at the ophthalmic segment of the ICA; and the angles between the communicating segment of the ICA and the ophthalmic segment of the ICA and a line perpendicular to the cranial base, which reflect the tortuosity of the ICA. These parameters were measured based on preoperative CTA results. RESULTS: In a total of 21 patients (32.3%), PVC was difficult to perform with the usual pterional approach. In 6 patients, temporary artery occlusions (TAOs) were difficult to achieve because of severe atherosclerotic wall changes in the ophthalmic segment of the ICA. For 15 patients, the ACPs overhanging the ophthalmic segment of the ICA obstructed the ability to secure a space for TAO. In the 21 patients with PVC difficulty, ACL alone, cervical ICA exposure alone, and both ACL and cervical ICA exposure were conducted in 6, 8, and 7 patients, respectively. Multivariate analysis with binary logistic regression revealed that the maximum diameter of the aneurysm (p = 0.041), the distance between the proximal neck of the aneurysm and the ACP tip (p = 0.002), and calcification of the ICA ophthalmic segment (p = 0.001) were significant predictive factors for difficulties with PVC. A receiver operating characteristic curve analysis revealed that a distance between the proximal aneurysmal neck and the ACP tip of ≤ 5.4 mm was the best cutoff value for predicting the difficulty of attaining PVC (area under the curve 0.800, sensitivity 80.0%, specificity 80.0%). CONCLUSIONS: A short distance between the proximal aneurysmal neck and the ACP tip and the presence of calcification at the ophthalmic segment of the ICA on preoperative CTA are helpful for predicting the difficulty of achieving PVC.

Sphenoparietal sinus transposition technique: optimization of the surgical corridor with preservation of prominent bridging veins between the brain and the cranial base during aneurysm clipping via the pterional approach.

OBJECTIVE: The sylvian bridging veins between the brain and the dura on the inner surface of the sphenoid wing can restrict brain retraction for widening of the lateral retrocarotid space during clipping surgery for internal carotid artery (ICA)-posterior communicating artery (PCoA) and basilar apex (BX) aneurysms. In such cases, the authors perform extradural anterior clinoidectomy with peeling of the temporal dura propria from the periosteal dura and inner cavernous membrane around the superior orbital fissure, with the incision of the dura mater stretching from the base of the temporal side to just before the distal dural ring of the ICA (termed by the authors as the sphenoparietal sinus transposition [SPST] technique). This technique displaces the bridging segment of the sylvian vein posteriorly and enables widening of the surgical space without venous injury. In this study, the authors observed the operative nuances and investigated the usefulness of this technique. METHODS: The authors retrospectively reviewed the medical charts of 66 consecutive patients with ICA-PCoA and BX aneurysms between January 2016 and July 2018. This technique was performed in 8 patients (5 patients with PCoA aneurysms and 3 with BX aneurysms) in whom the bridging segments of the sylvian veins between the brain and the skull base restricted brain retraction for widening of the surgical space. The surface areas of the lateral retrocarotid space and the aneurysm were measured at the most visible working angle before and after the SPST technique was performed. RESULTS: With the use of the SPST technique, an adequate surgical space for aneurysm clipping was obtained with preservation of the bridging veins in all patients. The mean surface areas of the lateral retrocarotid space (p = 0.002) and aneurysm (p = 0.001) were significantly increased from 18.3 ± 18.8 and 2.8 ± 2.5 cm2 before to 64.2 ± 21.1 and 20.9 ± 20.6 cm2, respectively, after the SPST technique was performed. CONCLUSIONS: The SPST technique enables displacement of the bridging segments of the sylvian veins without venous injury and enables widening of the surgical space around the lateral retrocarotid area.

CT findings of surgically resected large cell neuroendocrine carcinoma of the lung in 38 patients.

OBJECTIVE: We sought to assess the CT features of surgically resected large cell neuroendocrine carcinoma of the lung. MATERIALS AND METHODS: The cases of all patients who underwent surgical resection for primary lung cancer in a single institution from 1993 to 2000 and who received an initial diagnosis of poorly differentiated non-small cell lung carcinoma, small cell carcinoma, carcinoid tumor, and large cell neuroendocrine carcinoma were histologically reviewed. The findings for 43 patients were histologically reclassified and confirmed as large cell neuroendocrine carcinoma. The CT scans available for 38 patients were evaluated by two observers. RESULTS: In the 38 patients, six central tumors and 32 peripheral tumors, with diameters ranging from 12 to 92 mm (mean +/- SD, 32 +/- 19 mm), were identified. None of the tumors had air bronchograms or calcification in the mass or nodule. Of the 19 patients with thin-section CT scans, 14 (74%) showed the tumor-lung interface as well defined and five (26%) showed the interface to be ill defined. Lobulation was identified on 15 scans (79%) and spiculation was evident on six scans (32%). On contrast-enhanced CT scans, inhomogeneously enhanced tumors appeared to be larger (51 +/- 18 mm) than homogeneously enhanced tumors (25 +/- 10 mm; p < 0.001). At histopathologic examination, gross necrosis was noted in 20 of 28 patients who had undergone contrast-enhanced CT, and the cause of inhomogeneous enhancement on CT scans was determined to be intratumoral necrosis. Multiple microscopic necroses were present in all 28 patients. CONCLUSION: Large cell neuroendocrine carcinoma usually appears as a well-defined and lobulated tumor with no air bronchograms or calcification. The inhomogeneous enhancement (caused by necrosis) seen in large cell neuroendocrine carcinomas with large diameters is not necessarily apparent in small-diameter (< 33 mm) large cell neuroendocrine carcinomas, even if the tumor contains necrosis.

Intrapulmonary lymph nodes: thin-section CT features of 19 nodules.

PURPOSE: The purpose of this study was to describe the thin-section CT features of intrapulmonary lymph nodes that accompanied primary or metastatic lung tumors. METHOD: A retrospective analysis of thin-section CT features was performed on 19 nodules in 16 patients with pathologically confirmed intrapulmonary lymph nodes that accompanied primary or metastatic lung tumors. RESULTS: Of the 16 patients, 13 had a solitary nodule and 3 had two nodules. All nodules were distributed in the middle lobe, lingula, or lower lobe. On thin-section CT images, the nodule was located abutting the visceral pleura (n = 10) or within 8 mm of the visceral pleura (n = 9). The thin-section CT findings showed that most of the nodules were well circumscribed (n = 18), homogeneous (n = 19), ovoid (n = 10), or round (n = 9) and smaller than 12 mm in maximal diameter. The surrounding lung field was normal (n = 16). CONCLUSION: Intrapulmonary lymph nodes are subpleural in the lower lung field. On thin-section CT, they are well circumscribed, homogeneous, round or ovoid, and smaller than 12 mm in maximal diameter. In the differential diagnosis of subpleural nodules located in the lower lung field, it should be kept in mind that they may be intrapulmonary lymph nodes even though the patient has malignancy.