Preoperative assessment of local tumor extent in advanced rectal cancer: CT or high-resolution MRI?

BACKGROUND: We compared high-resolution magnetic resonance imaging (MRI) with computed tomography (CT) in the assessment of tumor infiltration in surrounding structures for locally advanced primary and recurrent rectal cancer. METHODS: Twenty-six patients with operable, locally advanced rectal cancer (15 recurrent and 11 primary) were evaluated with conventional pelvic CT and 1.5-T high-resolution MRI with a quadrature phased-array coil. The images were scored for invasion of nine neighboring pelvic structures, and the results were compared with surgical and histologic findings. RESULTS: A total of 234 structures in 26 patients was evaluated for tumor invasion. For MRI the, sensitivity was 97% and the specificity 98%; for CT, the sensitivity was 70% and the specificity was 85%. The difference in performance was statistically significant (p<0.001). The failure most frequently made on CT was the false-positive prediction of pelvic floor and piriform muscle invasion (14), whereas MRI showed only four false-positive predictions. MRI correctly predicted all four cases of sacral bone invasion, three of which were missed by CT. MRI was accurate in 20 patients (80%) and CT in only five patients (19%). CONCLUSION: High-resolution MRI using a quadrature phased-array coil is highly accurate and superior to CT in predicting tumor infiltration in surrounding structures for locally advanced primary or recurrent rectal cancer and is recommended in the preoperative work-up of these tumors.

Interpretation of renal angiography by radiologists.

OBJECTIVE: Different radiologists may show considerable variation in their interpretation of renal angiograms. We therefore wished to establish the reliability of their interpretation. DESIGN: Assessment of the intra- and inter-observer agreement of the interpretation of renal angiograms. SETTING: Tertiary referral university hospital. PATIENTS: Hypertensive patients suspected of renovascular hypertension on clinical grounds or on the basis of renography. INTERVENTIONS: Patients were prospectively selected to undergo a renal angiography via the femoral approach. MAIN OUTCOME MEASURES: Intra- and inter-observer agreement of the degree and site of stenosis. RESULTS: The difference between two estimates of the degree of stenosis ranged from 0 to 65% for the individual readers and from 0 to 75% between two readers. When the site of greatest stenosis was in the origin of the renal artery, the intra-observer agreement kappa ranged from 0.54-0.71, the inter-observer agreement across multiple readers being 0.43. In a post hoc analysis using two different cut-off points of stenosis (50 or 70%), the intra- and inter-observer agreement was better at the 70% cut-off-point. In a subset of patients with stenosis and a renin ratio greater than 1.5, both the intra- and inter-observer agreement were much better than when all angiograms were considered. CONCLUSIONS: Assessment of the diagnostic performance of three experienced radiologists in their interpretation of renal artery angiograms indicates that the intra- and inter-observer agreement with respect to their estimates of the degree of stenosis and the site of greatest stenosis are rather poor but their diagnostic performance improves in patients with stenosis and a renin ratio greater than 1.5. There is a need for more objective assessment of renal artery lesions.

Congenitally short trachea with compression of the left mainstem bronchus: MRI findings.

The MRI features of congenitally short trachea in a patient presenting with respiratory distress are presented. Compression of the left mainstem bronchus by the aortic arch, a recognised complication of this anomaly, could be demonstrated by MRI, obviating the need for other imaging modalities.

MR angiography of the iliac and upper femoral arteries using four different inflow techniques.

OBJECTIVE: The purpose of this study was to compare two inflow MR angiography pulse sequences obtained with and without systolic synchronization. We also compared these two MR angiography pulse sequences with conventional angiography. SUBJECTS AND METHODS: Thirty-one consecutive patients who were scheduled for conventional angiography because of symptomatic atherosclerotic occlusive disease of the iliac or femoral artery underwent MR angiography using four different MR angiography techniques. These techniques consisted of a multiple two-dimensional inversion prepulse gradient-recalled echo technique (turbo field-echo) obtained with and without systolic synchronization and a multiple two-dimensional gradient-recalled echo technique (fast field-echo) obtained with and without systolic synchronization. We then compared image quality and our ability to detect and grade degree and length of stenosis, using conventional angiography as the gold standard. RESULTS: The systolic-synchronized turbo field-echo sequence produced the best results both objectively and subjectively. Comparing systolic-synchronized turbo field-echo and fast field-echo techniques with conventional angiography regarding detection and grading degree of stenoses, we found no statistically significant differences. CONCLUSION: Systolic synchronization proved to be of significant importance for image quality. The systolic-synchronized turbo field-echo pulse sequence proved to be superior to the other three MR angiography techniques.

Evaluation of gracilis muscle transposition for fecal incontinence with magnetic resonance imaging.

Ten consecutive patients with incapacitating fecal incontinence were treated with 'anal dynamic graciloplasty' (transposition of the gracilis muscle around the anal canal and implantation of intramuscular electrodes connected with an implanted pulse generator, 6 weeks later) to achieve continence. We measured the gracilis muscle diameter immediately after transposition and before implantation of the stimulation device. It was found that gracilis diameter decreased from 12 (5 days after transposition) to 8 mm, 6 weeks later (mean decrease: 4 mm (95% confidence interval 3.6), n = 10, P < 0.05). In addition, morphology demonstrated a decrease of both Type I and Type II muscle fiber diameter and an increase in endomysial collagen. Despite this decrease in muscle (and muscle fiber) diameter, electrical stimulation of the transposed gracilis muscle increased the pressure into the anal canal from 37 to 55 mmHg (mean increase: 17 mmHg (95% confidence interval 6.29), P < 0.05). Fecal continence was achieved in seven (70%) of these patients. Further analysis revealed no correlations between reduction of the gracilis muscle diameter before implantation of the stimulation device and clinical outcome in terms of achieved continence and/or anal canal pressures. MRI is an excellent method to demonstrate the shape of gracilis muscle after transposition. However, the size of transposed gracilis muscle is not associated with the functional outcome.

The value of computed tomography to the staging of non-small-cell primary bronchogenic carcinoma: a prospective study.

The value of computed tomography (CT) for the diagnosis of non-small-cell primary bronchogenic carcinoma with regard to T and N classifications was prospectively evaluated in a series of 29 patients. The sensitivity of CT in evaluating the extension of tumor to pleura or mediastinum was 100%, with only a 76% specificity. Computed tomography demonstrated 73 lymph nodes greater than or equal to 10 mm and 55 lymph nodes less than 10 mm in 27 patients. Invasive staging showed 23 lymph nodes greater than or equal to 10 mm and 22 nodes less than 10 mm which were not visualized by CT. Malignant invasion was found at histology in only one of these lymph nodes. The majority of nodes not visualized by CT were localized in the left paratracheal group, right and left tracheobronchial groups and the aortopulmonary window.

The value of conventional radiography and computed tomography (CT) in diagnosis of pulmonary hamartoma.

No radiologic features are pathognomonic for hamartoma of the lung. Punctate or popcorn calcification, umbilication sign and CT density measurements should be helpful but are not diagnostic. Evidence of fat may suggest pulmonary hamartoma and CT density measurements may be helpful to detect this. A low CT number, however, may be the result of either the partial volume averaging or the presence of fat in the tumour. The definite diagnosis can be made only by histological examination after thoracotomy or transthoracic puncture.

Evaluation of the contribution of computed tomography to the staging of non-oat-cell primary bronchogenic carcinoma. A retrospective study.

In order to evaluate the contribution of computed tomography in the pre-operative staging of non-oat-cell primary bronchogenic carcinoma, the clinical T-classification by conventional methods only and after including CT was compared with the postsurgical T-classification in 21 patients. Furthermore, hilar or mediastinal lymph node enlargement as found by conventional methods only and after including CT was compared with the postsurgical N-classification. With conventional methods, T-classification was correctly evaluated in 15 of 21 patients (71%), 5 patients (24%) were underestimated and 1 patient (5%) was overestimated. Clinical T-classification including the results of CT, was correctly evaluated in 17 patients (80%), 2 patients (10%) were underestimated and 1 patient (5%) was overestimated. One patient (5%) was underestimated by bronchoscopy. Computed tomography demonstrated in 15 patients 31 lymph nodes in the mediastinum greater than 10 mm. and 18 lymph nodes smaller than 10 mm.; in 6 patients 9 lymph nodes smaller than 10 mm. were described. Only 4 patients with mediastinal lymph node enlargement were postoperatively classified as N2. Malignant growth was detected postoperatively in 10 lymph nodes smaller than 10 mm.