Dual-phase helical CT of pancreatic adenocarcinoma: assessment of resectability before surgery

OBJECTIVE: The aim of our study was to prospectively evaluate the accuracy of dual-phase helical CT in the preoperative assessment of resectability in patients with suspected pancreatic cancer using surgical and histopathologic correlation. SUBJECTS AND METHODS: Between January 1999 and December 2000, 76 patients with suspected pancreatic cancer underwent preoperative evaluation and staging with dual-phase helical CT (3-mm collimation for pancreatic phase, 5-mm collimation for portal phase). Iodinated contrast material was injected IV (170 mL at a rate of 4 mL/sec); acquisition began at 40 sec during the pancreatic phase and at 70 sec during the portal phase. Three radiologists prospectively evaluated the imaging findings to determine the presence of pancreatic tumor and signs of unresectability (liver metastasis, vascular encasement, or regional lymph nodes metastasis). The degree of tumor-vessel contiguity was recorded for each patient (no contiguity with tumor, contiguity of < 50%, or contiguity of > or =50%). RESULTS: Thirty-nine patients with pancreatic adenocarcinoma were surgically explored. Curative resections were attempted in 34 patients and were successful in 25. The positive predictive value for resectability was 73.5%. Nine patients considered resectable on the basis of CT findings were found to be unresectable at surgery because of liver metastasis (n = 5), vascular encasement (n = 2), or lymph node metastasis (n = 2). We found that the overall accuracy of helical CT as a tool for determining whether a pancreatic adenocarcinoma was resectable was 77% (30/39 patients). CONCLUSION: Dual-phase helical CT is a useful technique for preoperative staging of pancreatic cancer. The main limitation of CT is that it may not reveal small hepatic metastases.     

螺旋CT肝双期扫描在外生性肝癌诊断中的临床应用

目的：探讨螺旋CT肝双期扫描对外生性肝癌的诊断价值。方法：回顾性分析了7例外生性肝癌螺旋CT肝双期扫描的CT表现。结果：7例外生性肝癌与肝脏相连，3例有明显蒂部，2例肝右叶外生性肝癌向下至右侧盆腔内，6例其内可见CT“密度更低区”，3例压迫胃体及胃窦。螺旋CT肝动脉期6例肿瘤内可见不规则纡曲强化血管影。5例门静脉期肿瘤呈低密度；2例门静脉期部分肿瘤组织强化，密度增高。结论：螺旋CT肝双期扫描对外生性肝癌诊断有较高的临床价值。     

螺旋CT双期增强对胰腺癌病人的术前评估

目的 探讨螺旋CT双期增强对胰腺癌可切除性术前评估的价值。方法 对1999年5月～2003年3月期问行螺旋CT双期增强扫的45例诊断为胰腺癌病人的CT图像与22例手术结果进行对比研究，通过显示胰腺癌的部位、大小以及肿块对周围血管侵犯程度、远处器官转移以及后腹膜淋巴结转移，作出能否切除的术前评价。结果 45例胰腺癌病人中18例位于胰头，16例位于胰体尾，11例位于胰尾；27例患接受手术治疗，其中22例术前SCT认为肿瘤可切除，实际成功切除17例，成功切除的阳性预测值达77％，其他5例SCT认为肿瘤不能切除，实际手术均不能切除。结论 螺旋CT双期增强扫描可作为一种评价胰腺癌术前能否手术切除的有效方法。     

Enhancement characteristics of papillary renal neoplasms revealed on triphasic helical CT of the kidneys.

OBJECTIVE: The purpose of this study was to determine whether renal tumor enhancement or heterogeneity on triphasic helical CT scans is predictive of the papillary cell subtype or nuclear grade of renal cell carcinoma. MATERIALS AND METHODS: We reviewed the CT scans of 90 consecutive patients with renal masses who had undergone triphasic renal helical CT before a complete or partial nephrectomy (12 with papillary renal cell carcinomas, 66 with nonpapillary renal cell carcinomas, and 12 with benign lesions). Three radiologists who were unaware of the patients' diagnoses retrospectively and independently measured the attenuation of each patient's tumor, abdominal aorta, and normal renal parenchyma on the scans obtained during all three phases. Ratios of tumor-to-aorta enhancement and tumor-to-normal renal parenchyma enhancement were calculated for both of the phases performed after contrast material had been administered. Tumor heterogeneity was calculated as the difference between the highest and lowest attenuation values divided by the value of the enhancement of the aorta. Values were correlated with cell type and nuclear grade found at surgical pathology. RESULTS: Low tumor-to-aorta enhancement and low tumor-to-normal renal parenchyma enhancement ratios on the vascular phase scans significantly correlated (p < 0.001) with papillary renal cell type carcinoma. Homogeneity and tumor-to-parenchyma enhancement ratios on the parenchymal phase scans also significantly correlated (p < 0.001) with papillary renal cell type carcinoma. Heterogeneity and tumor enhancement ratios did not correlate with the nuclear grade of the carcinoma. CONCLUSION: Papillary renal cell carcinomas are typically hypovascular and homogeneous. A high tumor-to-parenchyma enhancement ratio (> or = 25%) essentially excludes the possibility of a tumor being papillary renal cell carcinoma. A low tumor-to-aorta enhancement ratio or tumor-to-normal renal parenchyma enhancement ratio is more likely to indicate papillary renal cell carcinoma.     

Myoepitheliomas of the soft palate: helical CT findings in two patients.

We describe the enhancement patterns of myoepithelioma in two patients with a soft palate mass. In the first case, helical CT revealed a faintly enhancing mass. Histologically, the tumor was composed of plasmacytoid cells in a background of rich myxoid stroma. Immunostaining for CD34 showed scanty blood vessels. In the second case, helical CT revealed an intensely enhancing mass. Histologically, the mass was a cellular tumor with fibrous stroma. Immunostaining for CD34 also showed frequent blood vessels.     

CT scanning in patients following surgery on the tongue and floor of mouth

Computed tomographic (CT) scanning was performed on 15 patients who had undergone carefully documented major surgery for malignancy to the tongue and floor of mouth in order to assess appearances of the face and neck following extensive resection. The appearances following a variety of operations, often with reconstruction, were identified. Familiarity with the normal post-operative anatomy allows the recognition of small volume recurrent tumour and the implementation of appropriate treatment.     

Subtraction CT angiography with controlled-orbit helical scanning for detection of intracranial aneurysms.

PURPOSEOur goal was to evaluate the utility of subtraction three-dimensional CT angiography for the detection of intracranial aneurysms.METHODSThirty-six patients with intracranial aneurysms were examined using newly devised controlled-orbit helical scanning and conventional angiography. Three-dimensional CT angiograms and subtraction 3-D CT angiograms were compared with conventional angiograms for their characterization of intracranial aneurysms.RESULTSFifty aneurysms were depicted on conventional angiograms, of which 48 (96%) were seen on the 3-D CT angiograms. Three-dimensional CT angiography was superior or equivalent to conventional angiography for depicting the shape, direction, and location of 33 (66%) of 50 aneurysms; however, it was often less useful than conventional angiography in delineating intracranial aneurysms adjacent to bone. Subtraction 3-D CT angiograms were obtained in 32 patients with a total of 46 aneurysms (in four cases, aneurysms were not depicted owing to excessive motion artifacts), and were superior or equivalent to conventional angiograms in all 46 cases.CONCLUSIONSSubtraction 3-D CT angiography with the use of controlled-orbit helical scanning is effective in the detection of intracranial aneurysms.     

Evaluation of foramen magnum in gender determination using helical CT scanning

Objective

The present research was undertaken to study the accuracy and reliability of the foramen magnum (FM) and some cranial measurements in gender classification through the use of reconstructed helical CT images.

Methods

88 patients (43 males and 45 females; age range, 20–49 years) were selected for this study. FM sagittal diameter, transverse diameter, area and circumference were measured and data were subjected to discriminant analysis for gender using multiple regression analysis.

Results

FM circumference and area were the best discriminant parameters that could be used to study sexual dimorphism with an overall accuracy of 67% and 69.3%, respectively. By using multivariate analysis, 90.7% of FM dimensions of males and 73.3% of FM dimensions of females were sexed correctly.

Conclusion

It can be concluded that the reconstructed CT image can provide valuable measurements for the FM and could be used for sexing when other methods are inconclusive.     

腰椎多层螺旋CT容积扫描的临床应用

目的 探讨腰椎多层螺旋CT容积(VH)扫描的临床应用价值.方法 按就诊顺序抽取1000例腰腿痛患者,腰椎VH模式扫描患者模拟重建常规单层(SS)L3～4、L4～5、15～S1椎间盘层面.VH扫描模式参数为120 kV,210 wAs,螺距1.5,平均扫描范围97.5 mm.SS扫描模式参数为120 kV、240 mAs、扫描范围为45.0 mm.比较2种扫描模式对腰椎疾病征象显示的差异及辐射剂量的不同.对所获数据进行配对资料x2检验和一致性检验分析.结果 VH扫描模式比ss扫描模式显示更多的征象,骨性椎管狭窄、椎间隙变窄、椎间盘脱出、侧隐窝狭窄、椎体病变、L5横突肥大、椎小关节方向异常、椎小关节退行性变、椎弓峡部裂、椎旁软组织异常的检出率,VH分别为11.8%(118例)、38.5%(385例)、9.3%(93例)、46.8%(468例)、31.4%(314例)、5.7%(57例)、25.4%(254例)、49.7%(497例)、9.9%(99例)、0.6%(6例),SS分别为5.6%(56例)、0、0.6%(6例)、27.9%(279例)、22.4%(224例)、1.2%(12例)、16.7%(167例)、37.2%(372例)、0.5%(5例)、0.2%(2例),2种模式下对每一种测量指标比较除椎旁软组织异常两者差异无统计学意义(P>0.05)外,其余测量指标差异均有统计学意义(P值均<0.05).与SS扫描模式相比,VH扫描模式下的骨性椎管狭窄、椎间隙变窄、椎间盘脱出和椎弓峡部裂的检出率分别提高6.2%(62例)、38.5%(385例)、8.7%(87例)和9.4%(94例),只能部分显示椎小关节面及方向、侧隐窝狭窄、L5横突肥大和椎旁软组织异常.46.7%(467例)(腰骶角>35°)的患者SS扫描模式下的定位线不能与椎间盘层面一致.VH扫描模式(164.9 mGy/cm)比SS扫描模式(147.0 mGy/cm)辐射剂量稍有增加.结论 腰椎多层螺旋CT VH扫描模式比SS扫描模式可以显示更多腰椎病变征象,且不受扫描架限制,辐射剂量增加不多.     

Suspected acute appendicitis: nonenhanced helical CT in 300 consecutive patients.

PURPOSE: To determine the accuracy of helical computed tomography (CT) without the oral, intravenous, or rectal administration of contrast material in confirming suspected acute appendicitis. MATERIALS AND METHODS: Three hundred consecutive patients referred from the departments of surgery and emergency medicine were examined for suspected acute appendicitis by using thin-section nonenhanced helical CT. All transverse CT scans were obtained in a single breath hold from the upper abdomen (T12 vertebra) to the pubic symphysis with 5-mm collimation and a pitch of 1.6. All scans were obtained without oral, intravenous, or rectal contrast material. Criteria for diagnosis of acute appendicitis included an enlarged appendix (> 6 mm) and periappendiceal inflammation. CT diagnoses were recorded prospectively. Final diagnoses were established with the results of surgical or clinical follow-up or both. RESULTS: There were 110 true-positive diagnoses, 181 true-negative diagnoses (63 of which were an alternative diagnosis correctly established prospectively), five false-negative diagnoses, and four false-positive diagnoses, which yielded a sensitivity of 96%, a specificity of 99%, and an accuracy of 97%. CONCLUSION: Nonenhanced helical CT is a highly accurate technique for diagnosing or excluding acute appendicitis. Developing experience with the technique and understanding the subtleties of interpretation can further improve diagnostic accuracy.     

Ventilation-perfusion scanning and helical CT in suspected pulmonary embolism: meta-analysis of diagnostic performance

PURPOSE: To perform meta-analysis of literature about the role of helical computed tomography (CT) and ventilation-perfusion (V-P) scanning in detection of acute pulmonary embolism (PE) by using summary receiver operating characteristic (ROC) curve analysis. MATERIALS AND METHODS: V-P scanning articles published from January 1985 to March 2003 and helical CT articles published from January 1990 to March 2003 in MEDLINE and EMBASE databases were included if (a) tests were performed for evaluation of acute PE, (b) conventional angiography was the reference standard, and (c) absolute numbers of true-positive, false-negative, true-negative, and false-positive results were available. Sensitivity analysis was conducted by excluding articles published before 1995. RESULTS: A total of 12 articles discussing helical CT and/or V-P scanning were included. With a random-effects model, pooled sensitivity for helical CT was 86.0% (95% confidence interval [CI]: 80.2%, 92.1%), and specificity was 93.7% (95% CI: 91.1%, 96.3%). V-P scanning yielded low sensitivity of 39.0% (95% CI: 37.3%, 40.8%) but high specificity of 97.1% (95% CI: 96.0%, 98.3%) with high probability threshold. V-P scanning yielded high sensitivity of 98.3% (95% CI: 97.2%, 99.5%) and low specificity of 4.8% (95% CI: 4.7%, 4.9%) with normal threshold. Regression coefficients for helical CT angiography were 0.588 (95% CI: -1.55, 2.74) and 4.14 (95% CI: -0.002, 8.28) versus V-P scanning with high and normal thresholds, respectively. Regression coefficients for helical CT angiography were 0.588 (95% CI: -1.55, 2.74) and 4.14 (95% CI: -0.002, 8.28) versus V-P scanning with high and normal thresholds, respectively. CONCLUSION: Helical CT has greater discriminatory power than V-P scanning with normal and/or near-normal threshold to exclude PE, while helical CT and V-P scanning with high probability threshold had similar discriminatory power in the diagnosis of PE.     

Hepatocellular carcinoma: role of unenhanced and delayed phase multi-detector row helical CT in patients with cirrhosis

PURPOSE: To determine, by using multi-detector row helical computed tomography (CT), the added value of obtaining unenhanced and delayed phase scans in addition to biphasic (hepatic arterial and portal venous phases) scans in the detection of hepatocellular carcinoma (HCC) in patients with cirrhosis. MATERIALS AND METHODS: Local ethical committee approval and patient consent were obtained. One hundred ninety-five patients (129 men, 66 women; mean age, 61 years; age range, 39-78 years) with 250 HCCs underwent multi-detector row helical CT of the liver. A quadruple-phase protocol that included unenhanced, hepatic arterial, portal venous, and delayed phases was performed. Analysis of images from hepatic arterial and portal venous phases combined, hepatic arterial and portal venous phases with the unenhanced phase, hepatic arterial and portal venous phases with the delayed phase, and all phases combined was performed separately by three independent radiologists. Relative sensitivity, positive predictive value, and area under the receiver operating characteristic curve (A(z)) were calculated for each reading session. RESULTS: Mean sensitivity and positive predictive values, respectively, for HCC detection were 88.8% (666 of 750 readings) and 97.8% (666 of 681 readings) for the combined hepatic arterial and portal venous phases, 89.2% (669 of 750 readings) and 97.8% (669 of 684 readings) for hepatic arterial and portal venous phases with the unenhanced phase, 92.8% (696 of 750 readings) and 97.3% (696 of 715 readings) for hepatic arterial and portal venous phases with the delayed phase, and 92.8% (696 of 750 readings) and 97.3% (696 of 715 readings) for all four phases combined. The reading sessions in which delayed phase images were available for interpretation showed significantly (P < .05) superior sensitivity and A(z) values. CONCLUSION: Unenhanced phase images are not effective for HCC detection. Because of the significant increase in HCC detection, a delayed phase can be a useful adjunct to biphasic CT in patients at risk for developing HCC.     

Triphasic CT in the diagnosis of acute mesenteric ischaemia

Objective

To evaluate the yield of each phase in a triphasic CT protocol used to diagnose acute mesenteric ischaemia (AMI).

Methods

Retrospective analysis of patients who underwent CT to exclude AMI was conducted. From 218 patients, 80 were randomly selected for analysis: 39 with proven AMI; 41 controls. Three readers evaluated the studies; two readers were provided with only portions of the examination to determine the yield of unenhanced CT (NECT) and CT angiography (CTA). The diagnostic accuracy of CT findings was calculated and compared between readers.

Results

The sensitivity and specificity of submucosal haemorrhage were 10 % and 98 %. Interobserver variability was poor (κ?=?0.17). All true-positive cases had other CT findings of AMI (n?=?4). There was no difference in the assessment of bowel enhancement between readers (P?<?0.05). There was no difference between readers (P?<?0.05) and interobserver variability was moderate to good when diagnosing arterial abnormalities without CTA. Sample size was small and errors occurred when using only the portal venous phase for this purpose.

Conclusion

NECT is not required for diagnosis of AMI. Splanchnic arterial abnormalities can be diagnosed without CTA although errors occur when using only the portal venous phase for this purpose.

Key points

? Triphasic CT is the current gold standard for diagnosing acute mesenteric ischaemia. ? Multiphase CT multiplies the radiation dose when compared to single phase CT. ? Each phase in a multiphase CT examination should be independently validated. ? Unenhanced CT is not required for diagnosis of acute mesenteric ischaemia. ? CT angiography should be performed for diagnosis of acute mesenteric ischaemia.     

Age-related expansion and reduction in aeration of the sphenoid sinus: volume assessment by helical CT scanning

BACKGROUND AND PURPOSE: Aeration of the sphenoid sinus expands with the development of the sphenoid bone, but scant detailed volumetric data regarding this process, as it evolves from childhood to old age, exist. Using helical CT scanning, we assessed age-related volumetric changes of the sphenoid sinus. METHODS: We used CT data obtained from 214 patients (age range, 1 to 80 years; 111 male and 103 female subjects) with middle or inner ear disease to assess the extent of sphenoid aeration. We also determined volumes of the sphenoid sinuses on 1.0- or 1.5-mm reformatted images by integrating the sinus air (< or = -900 HU) area. RESULTS: Sphenoid sinus aeration began as a doublet in the anterior boundary of the sphenoid bone by the age of 5 years, with patients more than 6 years old exhibiting varying degrees of aeration. The aeration on both sides continued to expand until the third decade of life. The maximum average volume was 8.2 +/- 0.5 cm3. Thereafter, the volume decreased gradually, with the average volume in the seventh decade of life being 71% of the maximum level. The aeration of the peripheral portions of the sphenoid bone, such as the pterygoid process, anterior clinoid process, and dorsum sella, occurred predominantly after closure of the spheno-occipital suture, and showed a tendency to recede during aging. CONCLUSION: Volumetric assessment of the sphenoid sinus by helical CT scanning revealed age-related expansion and reduction in aeration.     

Crohn's disease evaluation: comparison of contrast-enhanced MR imaging and single-phase helical CT scanning

The purpose of this study was to evaluate the use of gadolinium and barium-enhanced magnetic resonance (MR) imaging in detecting intestinal and extraintestinal Crohn's disease and compare MRI with contrast-enhanced helical computed tomography (CT). Twenty-six patients with Crohn's disease underwent imaging examinations, including gadolinium-enhanced, fat suppressed fast multiplanar spoiled gradient-recalled (FMPSPGR) MR imaging with oral 2% barium sulfate and rectal water and with helical CT using i.v. and positive (13) or negative (13) intestinal contrast material. MR images and CT scans were reviewed separately by two radiologists for bowel wall thickness and enhancement, presence of abscess, phlegmon, and fistula. MR images and CT scans were then compared side by side. Surgical, endoscopic, and histopathologic findings and results of barium studies were reviewed to determine the location and severity of involvement of intestinal Crohn's disease. Depiction of mural thickening and/or enhancement was superior on the MR images, which showed 55 (85%) and 52 (80%) of 65 abnormal bowel segments for the two observers, compared with helical CT, which showed 39 (60%) and 42 (65%; P < 0.001, P < 0.05) of bowel segments affected by Crohn's disease. Segments of bowel with moderate or marked mural thickening were depicted equally on MR imaging and helical CT. In mildly diseased segments of bowel, with only slight thickening and enhancement, MR imaging depicted 22 (79%) and 19 (68%) of 28 segments, compared with helical CT, which depicted 9 (32%; P < 0.01), and 13 (46%; P > 0.05) of 28 segments. In the side-by side comparison, MR imaging was preferred over helical CT for depicting normal bowel wall (MR 71%, CT 4%, equal 25%; P < 0.001), mural thickening (MR 41%, CT 11% equal 48%; P < 0.01), mural enhancement (MR 89%, equal 11%; P < 0.001), and overall GI tract evaluation (MR 52%, CT 10%, equal 38%; P < 0.001). Gadolinium-enhanced MR imaging with oral dilute barium sulfate and rectal water depicts intestinal and extraintestinal changes of Crohn's disease and shows promise as a clinically useful tool.     

Dysplastic nodules in liver cirrhosis: detection with triple phase helical dynamic CT

The purpose of this study was to determine the sensitivity of triple phase helical dynamic CT for detecting dysplastic nodules in patients with liver cirrhosis. 76 dysplastic nodules were confirmed by histopathological examination of the liver specimens after surgical resection in 21 patients or after explantation of the whole liver in 20 patients. Triple phase helical dynamic CT including arterial, portal venous and delayed phases was performed as a pre-operative evaluation for hepatocellular carcinoma. Two readers retrospectively evaluated the images. The presence of dysplastic nodules was determined by one-to-one correlation of the CT images and the pathological results in terms of the anatomical location and size of each nodule. Helical dynamic triple phase CT depicted eight of 76 dysplastic nodules (10%): five of 35 high grade dysplastic nodules (14%) and three of 41 low grade dysplastic nodules (7%). Triple phase helical dynamic CT is insensitive for detection of dysplastic nodules in cirrhotic livers.