Primary staging of laryngeal and hypopharyngeal cancer: CT,MR imaging and dual-energy CT

Laryngeal and hypopharyngeal cancer, in particular T4a disease associated with cartilage invasion and extralaryngeal spread, needs to be evaluated accurately because treatment can impact heavily on a patient's quality of life. Reliable imaging tools are therefore indispensible. CT offers high spatial and temporal resolution and remains the preferred imaging modality. Although cartilage invasion can be diagnosed with acceptable accuracy by applying defined criteria for combinations of erosion, lysis and transmural extralaryngeal spread, iodine-enhanced tumors and non-ossified cartilage are sometimes difficult to distinguish. MR offers high contrast resolution for images without motion artifacts, although inflammatory changes in cartilage sometimes resemble cartilage invasion. With dual-energy CT, combined iodine overlay images and weighted average images can be used for evaluation of cartilage invasion, since iodine enhancement is evident in tumor tissue but not in cartilage. Extralaryngeal spread can be evaluated from CT, MR or dual-energy CT images and the routes of tumor spread into the extralaryngeal soft tissue must be considered; (1) via the thyrohyoid membrane along the superior laryngeal neurovascular bundle, (2) via the inferior pharyngeal constrictor muscle, and (3) via the cricothyroid membrane. Radiologists need to understand the advantages and limitations of each imaging modality for staging of laryngeal and hypopharyngeal cancer.     

MR imaging of laryngeal cancer

Forty-four consecutive patients with laryngeal carcinomas presenting at different stages of the disease were investigated by magnetic resonance (MR) imaging. Twelve patients (six with primary lesions and six with recurrent tumors) underwent laryngectomy, and the macro- and microscopic appearance of the slice specimens were correlated with MR imaging. In the remaining patients surgery was not performed, and MR results are compared with the laryngoscopic findings. Cancerous tissue was seen on T1-weighted images as a homogeneous mass of intermediate signal intensity. slightly higher than infrahyoid muscles. The MR examinations failed mainly in patients with tumor recurrence who had undergone previous radiation treatment.     

Mycetoma: comparison of MR imaging with CT

Magnetic resonance (MR) images obtained in 18 patients with pathologically confirmed mycetoma in the body (n = 4) or lower extremity (n = 14) were retrospectively reviewed and compared with computed tomographic (CT) scans in 15 patients and surgical findings in 10. T1-weighted images showed an infiltrating mass (same signal intensity as muscle) involving skin, subcutaneous fat, muscles, tendons, and other tissues. On T2-weighted images, the mass and affected structures showed moderately increased signal intensity. Bone marrow involvement was detected in seven patients and was best visualized on T1-weighted images. CT showed moderate enhancement of the infiltrative process in all patients. Bone changes, seen in nine, included coarse trabeculation, periosteal reaction, endosteal proliferation, and patchy destruction. MR imaging and CT were comparable and correlated well with surgery in showing the extent of soft-tissue involvement. Early bone changes (important for therapy planning for pedal mycetoma) were seen only at CT. The study showed that MR imaging is sensitive for assessing the extent of mycetoma in the soft tissues. CT should be the method of choice for staging pedal lesions because it can be used to detect early bone involvement.     

Temporal-lobe epilepsy: comparison of CT and MR imaging

In 50 patients with temporal-lobe epilepsy, CT and MR findings were compared. Axial CT scans were obtained before and after administration of contrast material. Coronal MR imaging was carried out with two spin-echo (SE) sequences with a repetition time of 1600 msec and echo times of 35 or 70 msec (SE 1600/35, SE 1600/70). A focal lesion was detected by CT in 12 cases and by MR in 16 cases. If discrete attenuation or signal abnormalities are also taken into account, CT provided a positive finding in 13 cases and MR imaging in 20 cases. With the exception of a small calcification, all the lesions revealed on the CT scans were also detected on the MR images. Among the examinations assessable for temporal-lobe asymmetry, signs of a unilateral reduction in temporal-lobe size were seen on two of 35 CT scans and on 15 of 38 MR images. In three patients who had temporal-lobe resection, a subsequent comparison was made between CT, MR imaging, and pathology. Histologically proven glial reactions that could not be detected on CT were demonstrated as high-signal-intensity lesions on the SE 1600/70 image. We conclude that MR scanning, with its higher sensitivity, superior image quality, and ability of multiplanar imaging, should be the imaging technique of choice in the diagnosis of temporal-lobe epilepsy.     

MR portography: Preliminary comparison with CT portography and conventional MR imaging

Magnetic resonance (MR) imaging with arterial portography (MRAP) was compared with computed tomography with arterial portography (CTAP) and conventional MR imaging for preoperative evaluation of hepatic masses in eight patients (nine studies). Twenty contiguous, 10-mm-thick-section CTAP images were obtained. MR imaging included T1- and T2-weighted spin-echo and fast multiplanar SPGR (spoiled gradient-recalled acquisition in the steady state) techniques. For MRAP, 0.1 mmol/kg gadopentetate dimeglumine was injected into the superior mesenteric artery. Portographic-phase, 8-mm-thick-section, axial SPGR images were first obtained, followed by “systemic phase” SPGR images. Lesions were seen best on the portographic-phase MRAP images and were less conspicuous on the systemic-phase MRAP, CTAP and conventional MR images. Of 19 visualized lesions, 18 were seen with MRAP; however; five subcentimeter lesions seen with MRAP were not seen with conventional MR imaging or CTAP. Systemic recirculation of iodinated contrast material from the bolus and from previous angiography is a potential limitation of CTAP. For both CTAP and MRAP, optimal results are expected if all images are obtained during a single breath hold, within seconds of the onset of contrast agent administration.     

MR imaging of extracranial hematomas: comparison with CT

Thirty MR examinations of twenty-five patients with extracranial hemorrhagic lesions were reviewed. Comparative CT studies were available in 11 patients. The acute hematomas (less than 3 days old) showed intermediate intensity on the short TR (0.5 sec.) and increased in signal intensity on the long TR (2.0 sec.). The MR appearance of acute hematoma was not specific. Clot (more than 3 days old) demonstrated an intermediate intensity on the short TR and increased markedly in signal intensity on the long TR equaling the signal intensity of fat. Serum (more than 3 days old) was imaged as a high intensity lesion on both short and long TR. It is concluded that MR can be very useful for the differential diagnosis of subacute and chronic hemorrhagic lesions from other lesions.     

Invasion of the neurovascular bundle by prostate cancer: evaluation with MR imaging

Preservation of the neurovascular bundle (NVB) and potency without compromising tumor control are current objectives of radical retropubic prostatectomy as treatment for prostate cancer, but preoperative determination of whether cancer has invaded the NVB can be difficult. The use of conventional body-coil magnetic resonance (MR) imaging to make this preoperative determination was evaluated in 50 patients with biopsy-proved cancer. All patients underwent radical retropubic prostatectomy after MR imaging. MR imaging, surgical, and pathologic data were correlated relative to tumor location and volume, Gleason grade, presence of capsular penetration, and depth of NVB invasion. The sensitivity of MR imaging for invasion was 68%, specificity was 59%, and overall accuracy was 64%. Results of this study indicate that MR imaging can help identify the NVB and predict invasion of the NVB by tumor, but the usefulness of the technique is limited by the lack of spatial resolution associated with use of the whole-body coil.     

Evaluation of patellar cartilage surface lesions: comparison of CT arthrography and fat-suppressed FLASH 3D MR imaging

The aim of this study was to evaluate the sensitivity and specificity of fat-suppressed fast low-angle shot (FLASH) 3D MR imaging in the detection of patellar cartilage surface lesions in comparison with CT arthrography. Fifty patients, with or without symptoms of chondromalacia, were prospectively examined by CT arthrography and fat-suppressed 3D gradient-echo MR imaging. All MR examinations were evaluated by three observers, two of them reaching a consensus interpretation. The lesions were graded according to their morphology and their extent. The CT arthrography was considered as the reference examination. For both sets of observers, the final diagnosis of chondromalacia was obtained in 92.5 %. The specificity was 60 % on a patient-by-patient basis. Fissures were missed in 83 and 60 %, respectively, but were isolated findings only in 2.5 % of the cases. Considering ulcers involving more than 50 % of the cartilage thickness, 65 and 88 %, respectively, were recognized. Fat-suppressed FLASH 3D is an adequate pulse sequence for the detection of patellar cartilage ulcers. It can be applied on a routine clinical basis, but it does not show as many fissures as CT arthrography and is less precise for grading of lesions. Received 30 July 1997; Revision received 23 December 1997; Accepted 29 December 1997     

Bladder cancer: staging with CT and MR imaging

Magnetic resonance (MR) imaging and computed tomography (CT) were compared in 30 patients with histologically proved bladder cancer. MR imaging was accurate in depicting the presence or absence of extravesical spread in 22 patients (accuracy, 73%; sensitivity, 82%; specificity, 62%), and CT was accurate in 24 patients (accuracy, 80%; sensitivity, 94%; specificity, 62%). The MR examinations of two patients were of undiagnostic quality and therefore considered to be technical failures. Each technique resulted in five false-positive and one false-negative examination for the diagnosis of extravesical tumor spread. In 28 patients the integrity of the bladder wall was assessed with MR imaging. In 22 patients the bladder wall was disrupted, and 18 of these patients had deep muscle invasion. In six patients the bladder wall was intact, and none of these patients had evidence of deep muscle invasion at pathologic examination. In this study MR imaging was slightly inferior to CT in the delineation of invasive tumors beyond the bladder wall. However, if one excludes from analysis the two patients with undiagnostic studies, there is no significant difference in accuracy between the two techniques.     

Major salivary gland masses: comparison of MR imaging and CT

Computed tomography (CT) and magnetic resonance (MR) imaging studies were done prospectively in 21 unselected patients in whom 28 major salivary glands had pathologic changes. Blinded and final readings were used to establish the relationship of the lesion to the plane of the facial nerve (parotid masses), whether the lesion was intrinsic to the gland, and whether the lesion was aggressive. In the blinded reading, CT was superior to MR imaging in eight instances; in the final reading, however, with clinical information available, CT was superior in four cases of inflammatory salivary gland "masses." CT and MR imaging provided the same diagnostic information in all cases of salivary gland neoplasms. T1- and T2-weighted images proved of equal value in detection of salivary gland lesions, and use of both provided no additional specificity. In most cases, T1-weighted images alone provided the information necessary for surgical management. MR imaging is a reasonable first choice if a neoplasm is likely; the potential for improved tissue contrast at the margins of a tumor may be particularly useful. If a mass may be of inflammatory origin, contrast material-enhanced CT is a more reasonable first choice.     

Staging of malignant pleural mesothelioma: comparison of CT and MR imaging

OBJECTIVE: This article compares the accuracy of CT with that of MR imaging in staging of malignant pleural mesothelioma. SUBJECTS AND METHODS: Ninety-five patients were enrolled in a prospective staging protocol based on the International Mesothelioma Interest Group staging system. Sixty-five patients underwent CT and MR imaging and a surgical procedure (excluding percutaneous needle biopsy) to stage and resect the tumor. Receiver operating characteristic analyses were performed. CT and MR scans were interpreted independently by observers who were unaware of the results of the other imaging study; these imaging findings were compared with the results of surgery and pathologic examination. RESULTS: The areas under the receiver operating characteristic curves for eight of 10 features revealed by imaging showed no statistically significant differences between CT and MR imaging. However, MR imaging was superior to CT in revealing invasion of the diaphragm (A(z) = .55 for CT versus .82 for MR imaging) and in revealing invasion of endothoracic fascia or solitary resectable foci of chest wall invasion (A(z) = .46 for CT; A(z) = .69 for MR imaging). Several anatomic regions could not be evaluated because positive findings at surgery were rare. CONCLUSION: CT and MR imaging are of nearly equivalent diagnostic accuracy in staging malignant pleural mesothelioma. MR imaging is superior to CT in revealing solitary foci of chest wall invasion and endothoracic fascia involvement and in showing diaphragmatic muscle invasion; however, this advantage does not affect surgical treatment. For cost reasons, CT should be considered the standard diagnostic study before therapy.     

MR imaging of intracranial cysticercosis: comparison with CT and anatomopathologic features

Eight patients with neurocysticercosis were studied with CT and magnetic resonance (MR) imaging. Two cysts were shown better with MR than with CT. A conspicuous, high-intensity mural nodule containing the scolex allowed specific identification of intraventricular and parenchymal cysticerci. CT evidence of calcification and metrizamide enhancement in the nodule was also noted in one case. Racemose cysts were seen in the cerebellopontine angle and under the anterior septum pellucidum. Fluid in apparently live cysticerci and in racemose cysts had MR signal properties closely paralleling CSF. A thin subependymal or subpial rim of high signal intensity around the intraventricular and one of the racemose cysts was consistent with tissue reaction and aided diagnosis. While MR showed only one of numerous calcifications, it may be more sensitive than CT in the recognition of perifocal edema and of parenchymal and subarachnoid cysts, may replace invasive ventriculography in the diagnosis of intraventricular cysts, and may be useful in determining the viability of cysts and their response to therapy.     

良性周围神经鞘瘤的CT、MR表现与病理对照

目的 探讨周围神经鞘瘤的CT、MR及病理表现.方法 回顾性分析18例经病理证实的周围神经鞘瘤的CT、MR表现,其中发生在颈椎和胸椎椎间孔内的6例、颌面部1例、眼眶1例、颈部1 例、枕部1 例、纵隔1 例、胸壁1 例、腹壁1例、上臂2例及下肢3例,其中3例为多发.结果 肿瘤呈椭圆形或结节状,边界清楚光滑,沿神经走行方向生长,1例有邻近椎间孔扩大,10例有完整包膜,直径＞2 cm内部易发生出血及液化坏死,本组共6例.CT显示肿瘤包膜密度高,包膜内肿瘤组织密度低于正常肌肉组织.MR对显示肿瘤内部出血坏死、囊变较好,与病理结果基本相符.MR T1WI 显示肿瘤呈中～低信号,T2WI 呈不均匀高信号,增强后轻度不均匀强化,延迟强化较明显.其中显示靶征8例,神经出入征10例,包膜征9例,脑脊液尾征4例,肌肉萎缩水肿1例,坏死囊变8例,椎间孔扩大1例.结论 CT、MR对周围神经鞘瘤的诊断有重要价值.