A concurrent, deep learning-based computer-aided detection system for prostate multiparametric MRI: a performance study involving experienced and less-experienced radiologists

OBJECTIVES

To evaluate the effect of a deep learning-based computer-aided diagnosis (DL-CAD) system on experienced and less-experienced radiologists in reading prostate mpMRI.

METHODS

In this retrospective, multi-reader multi-case study, a consecutive set of 184 patients examined between 01/2018 and 08/2019 were enrolled. Ground truth was combined targeted and 12-core systematic transrectal ultrasound-guided biopsy. Four radiologists, two experienced and two less-experienced, evaluated each case twice, once without (DL-CAD-) and once assisted by DL-CAD (DL-CAD+). ROC analysis, sensitivities, specificities, PPV and NPV were calculated to compare the diagnostic accuracy for the diagnosis of prostate cancer (PCa) between the two groups (DL-CAD- vs. DL-CAD+). Spearman's correlation coefficients were evaluated to assess the relationship between PI-RADS category and Gleason score (GS). Also, the median reading times were compared for the two reading groups.

RESULTS

In total, 172 patients were included in the final analysis. With DL-CAD assistance, the overall AUC of the less-experienced radiologists increased significantly from 0.66 to 0.80 (p = 0.001; cutoff ISUP GG ≥ 1) and from 0.68 to 0.80 (p = 0.002; cutoff ISUP GG ≥ 2). Experienced radiologists showed an AUC increase from 0.81 to 0.86 (p = 0.146; cutoff ISUP GG ≥ 1) and from 0.81 to 0.84 (p = 0.433; cutoff ISUP GG ≥ 2). Furthermore, the correlation between PI-RADS category and GS improved significantly in the DL-CAD + group (0.45 vs. 0.57; p = 0.03), while the median reading time was reduced from 157 to 150 s (p = 0.023).

CONCLUSIONS

DL-CAD assistance increased the mean detection performance, with the most significant benefit for the less-experienced radiologist; with the help of DL-CAD less-experienced radiologists reached performances comparable to that of experienced radiologists.

KEY POINTS

• DL-CAD used as a concurrent reading aid helps radiologists to distinguish between benign and cancerous lesions in prostate MRI. • With the help of DL-CAD, less-experienced radiologists may achieve detection performances comparable to that of experienced radiologists. • DL-CAD assistance increases the correlation between PI-RADS category and cancer grade.

Impact on Image Quality and Radiation Dose of Third-Generation Dual-Source Computed Tomography of the Coronary Arteries

The aim of this study was to assess the image quality (IQ) and radiation dose of third-generation dual-source computed tomography (CT) coronary angiography (cCTA) in comparison with 64-slice single-source CT. This retrospective study included 140 patients (73 men, mean age 62 ± 11 years) with low-to-intermediate probability of coronary artery disease who underwent either third-generation dual-source cCTA using prospectively electrocardiography-triggered high-pitch spiral acquisition (n = 70) (group 1) or retrospective electrocardiography-gated cCTA on a 64-slice CT system (n = 70) (group 2). Contrast-to-noise and signal-to-noise ratios were measured within the aorta and coronary arteries. Subjective IQ was assessed using a 5-point Likert scale. Effective dose was estimated using specific conversion factors. The contrast-to-noise ratio of group 1 was significantly higher than group 2 at all levels (all p <0.001). Signal-to-noise ratio of group 1 was also significantly higher than group 2 (p <0.05), except for the distal left circumflex artery. Subjective IQ for group 1 was rated significantly better than for group 2 (median score [25th to 75th percentile]: 1 [1 to 2] vs 2 [2 to 3]; p <0.001). The median effective dose was 1.55 mSv (1.09 to 1.88) in group 1 versus 12.29 mSv (11.63 to 14.36) in group 2 (p <0.001) which corresponds to a mean radiation dose reduction of 87.4%. In conclusion, implementation of third-generation dual-source CT system for cCTA leads to improved IQ with significant radiation dose savings.

Psoriatic arthritis and rheumatoid arthritis: findings in contrast-enhanced MRI

OBJECTIVE

Our objective was to define typical MRI findings of the wrist and the hand in patients with psoriatic arthritis (PsA) and rheumatoid arthritis (RA).

MATERIALS AND METHODS

Eighteen PsA and 21 RA patients with arthralgia of the wrist or hand joints underwent gadolinium-enhanced MRI of the wrist and hand. Two experienced radiologists interpreted abnormalities in consensus with respect to periarticular soft-tissue swelling, synovitis with or without effusion, periostitis, bone edema, bone erosions, bone cysts, and tenosynovitis. The distribution of the abnormalities also was evaluated.

RESULTS

Erosions were statistically more frequent in patients with RA (p < 0.05). Periostitis was statistically seen more frequently in patients with PsA (p < 0.05). No statistically significant difference was found in the frequency of synovitis, bone marrow edema, bone cysts, and tenosynovitis between the two groups (p > 0.05). The radiocarpal joint, the midcarpal joints, the carpometacarpal joints, and the metacarpophalangeal joints were significantly affected more frequently in patients with RA than in patients with PsA (p < 0.05), whereas the proximal interphalangeal joints were significantly more frequently affected in patients with PsA (p < 0.05).

CONCLUSION

Periostitis and synovitis of the proximal interphalangeal joints are typical MRI findings in patients with PsA, whereas synovitis with erosions of the wrist, the midcarpal joints, the carpometacarpal joints, and the metacarpophalangeal joints are typical findings in patients with RA.

Adrenocortical carcinomas and adrenal pheochromocytomas: mass and enhancement loss evaluation at delayed contrast-enhanced CT

PURPOSE

To retrospectively measure the adrenal gland attenuation and the percentage loss of adrenal gland enhancement at delayed contrast medium-enhanced computed tomography (CT) in patients with adrenocortical carcinomas and pheochromocytomas and to compare these data with those in patients with adenomas and metastases.

MATERIALS AND METHODS

The study protocol was approved by the ethics committee, which waived informed consent. Eleven patients with proved adrenocortical carcinoma, 17 with proved pheochromocytoma, 23 with adrenal adenoma, and 16 with metastasis to the adrenal gland underwent helical CT. Nonenhanced CT was followed by contrast-enhanced CT 1 minute and 10 minutes later. Attenuation and enhancement loss values were calculated.

RESULTS

The mean attenuation of adenomas (8 HU +/- 18 [standard deviation]) was significantly lower than those of adrenocortical carcinomas (39 HU +/- 14), pheochromocytomas (44 HU +/- 11), and metastases (34 HU +/- 11) on nonenhanced CT scans (P < .001). Although the mean attenuation values for nonadenomas (ie, adrenocortical carcinomas, pheochromocytomas, and metastases) were significantly higher than the value for adenomas on the 1-minute contrast-enhanced CT scans (P < .001), there was more overlap in attenuation between adenomas and nonadenomas on contrast-enhanced scans than on nonenhanced scans. On the 10-minute delayed contrast-enhanced scans, the mean attenuation of adenomas (32 HU +/- 17) was significantly lower than the mean attenuations of carcinomas (72 HU +/- 15), pheochromocytomas (83 HU +/- 14), and metastases (66 HU +/- 13) (P < .001). At optimal threshold values of 50% for absolute percentage of enhancement loss and 40% for relative percentage of enhancement loss at 10 minutes, both the sensitivity and the specificity for the diagnosis of adenoma were 100% when adenomas were compared with carcinomas, pheochromocytomas, and metastases.

CONCLUSION

The enhancement loss in adrenocortical carcinomas and pheochromocytomas is similar to that in adrenal metastases but significantly less than that in adrenal adenomas. The percentage change in contrast material washout is a useful adjunct to absolute CT attenuation values in differentiating adrenal adenomas from adrenocortical carcinomas and pheochromocytomas.

Helical CT of the small bowel with an alternative oral contrast material in patients with Crohn disease

BACKGROUND

We assessed the usefulness of helical computed tomography (CT) with a negative oral contrast material for detecting Crohn disease.

METHODS

Thirty-eight patients with proven Crohn disease were examined. We administered a large volume of a new negative oral contrast material (Mucofalk suspended in water) and then proceeded with helical CT scanning. This technique is an alternative to CT and conventional enteroclyses that use a nasojejunal tube. Two radiologists interpreted the scans, and patients were interviewed about their tolerance of the procedure. We created multiplanar reformatted images in all cases. Potential of small bowel distention by Mucofalk was evaluated by two observers on a three-point scale, and interobserver agreement was calculated with kappa statistics.

RESULTS

All patients who underwent enteroclysis stated that CT was the more comfortable method, the taste of the peroral contrast medium was considered good by 52.6% and acceptable by 47.4%. Small bowel distention was excellent in 55% of cases, moderate in 26%, and poor in 19%, with an interoberserver agreement of 78%. CT findings correlated with enteroclysis in 27 patients who underwent both methods. Analysis of CT versus enteroclysis showed a sensitivity of 89% for CT versus 78% for small bowel enteroclysis.

CONCLUSION

Mucofalk CT is a simple, rapid, noninvasive, and accurate method of evaluating extramucosal manifestations of Crohn disease. The tubeless procedure improved patients' comfort and decreased time, cost, and radiation exposure.

Multiplanar spiral CT enterography in patients with Crohn's disease using a negative oral contrast material: initial results of a noninvasive imaging approach

The aim of this study was to prospectively define the role of multiplanar spiral CT enterography with a new negative oral contrast material for noninvasive assessment of the small bowel in patients with Crohn's disease. Thirty patients with established Crohn's disease prospectively underwent spiral CT enterography at 45-60 min after distension of the small bowel with 1400 ml of a negative oral contrast material (Mucofalk water enema). Spiral CT scans were obtained 50 s after administration of intravenous contrast material with the following parameters: 5-mm collimation; 7.5-mm/s table feed; and 3-mm reconstruction interval. The adequacy of bowel opacification, luminal distension, and the contribution of two-dimensional multiplanar reformatted imaging were assessed by two observers. Spiral CT imaging findings were compared with results of enteroclysis as well as endoscopic and histological findings in all patients. Spiral CT enterography with Mucofalk water enema was well tolerated in 29 of 30 patients. Findings on spiral CT enterography were comparable with those of barium studies in 25 of 30 patients, superior to those on barium studies in 4 patients, and inferior in 1 patient ( p<0.05). The addition of multiplanar reformatted images to axial spiral CT scans significantly improved observers' confidence in image interpretation ( p<0.05) but did not reveal additional abnormalities. Multiplanar spiral CT enterography with Mucofalk excellently provides information in patients with Crohn's disease. This technique accurately depicts the level of small bowel obstruction and the extent of inflammatory small bowel disease and its extraluminal complications.

[The value of different spiral CT phases in the detection of liver metastases]

PURPOSE

To assess the value of the non-contrast phase (NCP), hepatic-arterial phase (HAP) and portal-venous phases (PVP) for the detection of liver metastases by spiral CT.

METHODS

In order to detect liver metastases, 119 patients (58 women, 61 men; mean age: 62 years) underwent triphasic spiral CT (8 mm collimation, 12 mm table increment/rotation, 7 mm reconstruction increment). NCP, HAP (20 s delay) and PVP (70 s delay) scans were acquired (contrast medium injection rate: 4 ml/s). CT analysis comprised independent evaluation of the three scan series for detection and conspicuity of liver metastases (conspicuity score: 0 = not visible, 1 = barely visible, 2 = clearly visible, 3 = distinctly visible).

RESULTS

In 83 of the 119 patients, 478 liver metastases were detected (110 hypervascular and 368 hypovascular lesions). 285 (60 %) metastases were detected on NCP scans. Significantly more lesions were seen on HAP (n = 375, 78 %) and on PVP (n = 428, 90 %). No lesion was detected on NCP studies alone. For all detected metastases, mean conspicuity was 1.2 +/- 0.4 on NCP, 1.8 +/- 0.8 on HAP and 2.2 +/- 0.8 PVP. Hypervascular lesions were best seen on HAP with a conspicuity score of 2.0 +/- 0.8 versus 1.3 +/- 0.5 on NCP and 1.5 +/- 0.8 on PVP. Hypovascular lesions reached the highest conspicuity on PVP with 2.4 +/- 0.8 versus 1.2 +/- 0.4 on NCP and 1.7 +/- 0.7 on HAP.

CONCLUSION

For detection of liver metastases with spiral CT, contrast series seem to be sufficient. For tumors likely to seed hypervascular metastases, HAP scans should be applied in addition to the PVP.

Bilateral orbital pseudotumour due to Ormond's disease: MR imaging and CT findings

We present the MRI and CT findings in a 43-year old patient with bilateral orbital pseudotumour due to Ormond's disease.

Magnetic resonance imaging patterns of the development of the sphenoid sinus: a review of 800 patients

Accurate knowledge of age-related development and pneumatisation of the paranasal sinuses has become an important issue in diagnosing paranasal sinus diseases in infants and young adults. Magnetic resonance imaging (MRI) has the potential to assess bone marrow conversion and pneumatisation of the paranasal sinuses. We retrospectively reviewed 800 children aged 0-14 years undergoing brain MRI for various indications. T1-weighted sagittal and T2-weighted axial scans were evaluated for bone marrow conversion and development of pneumatisation of the sphenoid sinus. The sphenoid sinus had a uniformly low signal intensity on T1-weighted images in all children less than four months old. Signal intensity began to change to hyperintense marrow at the age of four months. Onset of pneumatisation was observed in 19% at the age of 12-15 months. Pneumatisation was complete in all patients older than 10 years. In conclusion, these data can be used as baseline standards of normal age-related development of the sphenoid sinus and can be of great value for the diagnostic and therapeutic management of pathologic conditions of the child's sphenoid sinus and its surrounds.

Helical CT angiography of stent-grafts in abdominal aortic aneurysms: morphologic changes and complications

Transfemoral placement of an endovascular stent-graft is increasingly be-ing used as an alternative to surgical repair in the treatment of abdominal aortic aneurysm, especially in high-risk patients. However, complications frequently occur after stent-graft placement. Helical computed tomographic (CT) angiography is a fast, minimally invasive procedure that is quickly becoming the imaging modality of choice for assessment of these complications. Thirty-nine patients who were treated for abdominal aortic aneurysm with stent-graft placement underwent helical CT angiography at routinely scheduled follow-up intervals or whenever complications were suspected. The resulting images were evaluated for the presence, extent, and origin of endovascular leaks. In addition, the position, shape, and patency of the stent-grafts were assessed. Findings included both graft-related (n = 4) and non-graft-related (n = 3) leaks, thrombosis of a graft limb (n = 3), distal migration of the stent-graft (n = 5), angulation of bifurcated stent-grafts distal to the main graft (n = 6), shrinkage of the abdominal aortic aneurysm (n = 7), enlargement of the aneurysm with secondary graft-related leaks (n = 2), and an aortoduodenal fistula (n = 1). Helical CT angiography can depict complications that develop after treatment of abdominal aortic aneurysms with endovascular stent-grafts. Long-term follow-up is required to determine the full spectrum and frequency of complications that may develop after initially successful repair.

[Differential diagnosis of space-occupying adrenal masses]

Computed tomography (CT) and magnetic resonance (MR) imaging are first line modalities in the evaluation of patients with adrenal gland masses, and have the potential to be very accurate for the localization of adrenal gland masses in patients with diseases associated with hyperfunctioning conditions of the adrenal gland. Both CT and MR imaging allow a specific diagnosis of acute adrenal hemorrhage, adrenal myelolipoma, and adrenal cysts. CT is also helpful in the assessment of patients with Addison's disease, particularly the subacute form secondary to granulomatous diseases. Quantitative evaluation of adrenal masses on unenhanced CT scans and/or qualitative analysis on chemical-shift MR imaging have been shown to be accurate in distinguishing adrenal adenomas from non-adenomas. Attenuation of 11 HE or less on unenhanced CT scans and/or signal loss on opposed phase MR images indicate adenoma with a high specificity and acceptable sensitivity. More recently, delayed-enhanced CT has yielded higher sensitivity and specificity values in distinguishing between adrenal adenomas and non-adenomas than both unenhanced CT and chemical-shift MR imaging do. On delayed-enhanced CT scans, adrenal adenomas exhibit a greater washout of contrast material than do adrenal non-adenomas. Therefore, adrenal non-adenomas have significantly higher attenuation than adenomas on delayed-enhanced CT scans obtained at several arbitrarily chosen time points (3-60 min) after the initiation of contrast material administration.

Giant liposarcoma of the esophagus: radiological findings

This case of an esophageal liposarcoma illustrates a polypoid lesion within the esophagus that extended from the left pyriform sinus to the distal esophagus above the gastric cardia. Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) showed an inhomogenously-enhancing intraluminal mass, while video-fluoroscopy revealed that the mass was adherent to the esophageal wall and was associated with esophageal dilatation and diminished peristalsis. This ninth reported case of esophageal liposarcoma is the first described where preoperative radiologic studies and endoscopy showed broad fixation of the tumor to the esophageal wall.

[Acute appendicitis in non-contrast spiral CT: a diagnostic luxury or benefit?]

PURPOSE

To evaluate the diagnostic accuracy of thin collimated unenhanced spiral-CT in patients with clinically suspected acute appendicitis and to determine the impact on patient management and overall costs.

METHOD

Unenhanced focussed appendiceal spiral-CT was performed in 56 patients (23 women and 33 men) with clinically suspected acute appendicitis. Scans were obtained from the L4 level to the symphysis pubis using 5 mm collimation, 7.5 mm table feed (pitch 1.5) and 4 mm increment without i.v., oral, or rectal contrast material. Prospective diagnoses based on CT findings were compared with surgical (and histopathological) results and clinical follow-up. The effect of spiral-CT on patient management and clinical resources was assessed.

RESULTS

29 patients (10 women and 19 men) underwent appendectomy. Unenhanced spiral-CT was an accurate imaging technique for the initial examination of patients with suspected acute appendicitis with a sensitivity of 95.4% and a specificity 100%, an accuracy of 98.2%, a positive predictive value of 100%, and a negative predictive value of 97.1%. In 27 patients with no evidence of acute appendicitis, an alternative diagnosis could be made in 24 patients by unenhanced spiral-CT.

CONCLUSION

Unenhanced spiral-CT is an accurate test to diagnose or to exclude acute appendicitis. Routine appendiceal spiral-CT can improve medical care and reduce the overall costs for patients suspected of having acute appendicitis.

[Radiologic staging of renal cell carcinoma]

The routine staging work-up for renal cancer includes a contrast-enhanced multiphasic spiral CT and a chest radiograph. If there is doubt regarding the presence and extent of (supradiaphragmatic) IVC thrombus, MR imaging should be performed. Dynamic contrast-enhanced MR imaging should be used in place of CT in any patient with severe renal dysfunction, symptomatic polycystic kidney disease, or a history of allergy to iodinated contrast media. Cavography is no longer needed in the era of (adaptive array detector) spiral CT and MR venography.

Computed tomography evaluation of adrenal masses

Computed tomography is the first line modality in the evaluation of patients with adrenal gland masses, and has the potential to be very accurate in the localization of adrenal gland masses in patients with diseases associated with hyperfunctioning conditions of the adrenal gland. Computed tomography allows a specific diagnosis of acute adrenal haemorrhage, adrenal myelolipoma, and adrenal cysts. It is also helpful in the assessment of patients with Addison's disease, particularly the subacute form secondary to granulomatous diseases. Quantitative evaluation of adrenal masses on unenhanced or delayed-enhanced computed tomography has been shown to be highly accurate in distinguishing adrenal adenomas from non-adenomas. Attenuation of 18 HU or less on unenhanced computed tomography scans indicates adenoma with a high specificity and acceptable sensitivity. On delayed-enhanced computed tomography scans, adrenal adenomas exhibit a greater washout of contrast material than do adrenal non-adenomas. Therefore, adrenal non-adenomas have significantly higher attenuation than adenomas on delayed-enhanced computed tomography scans obtained at arbitrarily chosen times (3-60 min) after the initiation of contrast material administration.

Chronic spinal subdural haematoma associated with intracranial subdural haematoma: CT and MRI

Chronic spinal subdural haematoma is a uncommon. We describe the CT and MRI appearances of chronic spinal and intracranial subdural haematomas following minor trauma. The aetiology, pathogenesis and differential diagnosis are discussed.

[Native spiral computerized tomography in patients with acute flank pain--sense or nonsense?]

PURPOSE

To compare the diagnostic efficacy and costs of native spiral-CT and intravenous urography (IVU) in the management of patients with acute flank pain.

METHOD

Native spiral-CT and IVU (following about 30 minutes after CT) were compared in 66 patients with acute flank pain followed by an IVU. The spiral-CT protocol was: 5-mm section thickness, 7.5-mm table feed and 3-mm increment. The analysis conducted independently by two radiologists entailed: (a) Morphology: presence of stone disease (yes-no), localization and size of calculi, periureteral and perirenal stranding, dilatation of the collecting system, and possible alternative diagnoses and (b) cost-effectiveness: direct and indirect costs.

RESULTS

Fifty-two patients had urolithiasis. The detection rate of renal and ureteric calculi was significantly higher with native spiral-CT than with IVU (100% vs. 69%, respectively) (p < 0.05). A specific sign of ureteric calculi was the so-called soft tissue "rim sign" (sensitivity 82% and specificity 100%, respectively). In 13 of 14 patients with acute flank pain with no evidence of urolithiasis alternative diagnoses could be made by spiral-CT. Spiral-CT was significantly more cost-effective than IVU in management.

CONCLUSION

Native spiral-CT is faster, more effective and less expensive than IVU in the management of patients with acute flank pain. Additionally, it poses less risk and has the capability for allowing alternative diagnoses. Therefore, unenhanced spiral-CT should be the first line modality in patients with acute flank pain.

Anterior and upward displacement of the inferior mesenteric vein:a new diagnostic clue to left paraduodenal hernias?

A 26-year-old man with acute deterioration of recurrent abdominal pain was admitted to the hospital. Plain film (abdominal radiographs), spiral computed tomography (CT), and barium contrast studies were performed. A left paraduodenal hernia causing acute jejunal obstruction was identified on upper gastrointestinal barium studies and spiral CT. Pre- and postsurgery examinations were compared, and relevant radiological findings were identified. Spiral CT provided excellent visualization of the pathognomonic displacement of the inferior mesenteric vein.

[Criteria for ultrasound differentiation of small angiomyolipomas (< or = 3 cm) and renal cell carcinomas]

PURPOSE

The purpose of this prospective study was to analyze whether ultrasound (US) features are helpful for the differentiation and characterization of small solid (< or = 3 cm) renal masses.

MATERIALS AND METHODS

70 small solid (< or = 3 cm) renal masses were evaluated sonographically with respect to size, location, echogenicity, homogeneity, shadowing, hypoechoic rim, and cystic regions. In addition, all masses were evaluated with spiral-computed tomography (CT). A diagnosis of angiomyolipoma (AML) was made when a lesion contained components with attenuation of fat (> -10 HU). The amount of fat and soft tissue of an AML detected on CT was correlated with the presence of shadowing seen on sonography.

RESULTS

10 (29%) of the 35 renal cell carcinomas (RCC) were hyperechoic to renal parenchyma, but no RCC was as echogenic as the renal sinus fat. Acoustic shadowing was only observed in AML. 11 (34%) AML with shadowing tended to have a larger amount of soft tissue. A hypoechoic rim and cystic regions were only found in RCC. 14 of 35 (40%) RCC showed a hypoechoic rim. Cystic regions were found in 12 of the 35 RCC (34%).

CONCLUSIONS

Renal cell carcinomas display a broad range of echogenicities indicating that small RCC (< or = 3 cm) and AML are not definitely distinguishable by their type of echogenicity. The presence of shadowing, a hypoechoic rim, and cystic regions enable differentiation of small (< or = 3 cm) AML from RCC with a high specificity. Accordingly, sonography has the potential to characterize small (< or = 3 cm) hyperechoic renal masses, with high specificity. However, the low sensitivity of these US features may require a CT for accurate diagnosis.

Multiphasic helical CT in diagnosis and staging of hilar cholangiocarcinoma

OBJECTIVE

The purpose of our study was to assess the potential of thin-section multiphasic helical CT in diagnosis and staging of hilar cholangiocarcinomas.

SUBJECTS AND METHODS

Identically collimated helical CT studies were performed before and during the hepatic artery dominant phase and during the portal vein dominant phase of contrast enhancement in 29 consecutive patients with proven hilar cholangiocarcinomas. Differences in attenuation between the tumor and the liver were calculated in each case by subtracting the average attenuation of the tumor from that of the liver. A four-point scale termed a "lesion conspicuity score" was used to determine rates of tumor detection. CT findings were correlated with surgically assessed extent of tumor, histologic findings, or both in all cases.

RESULTS

Ten (34%) of the 29 hilar cholangiocarcinomas were detected on unenhanced images. All hilar cholangiocarcinomas (100%) were seen on hepatic artery dominant phase scans, and 25 (86%) of 29 hilar cholangiocarcinomas were seen on portal vein dominant phase scans, regardless of the morphologic appearance. An infiltrating stenotic lesion was found in 17 (59%) of 29 patients, an exophytic hilar lesion was found in 11 patients (38%), and one patient (3%) had an intraluminal polypoid lesion. Mean differences in enhancement between infiltrating stenotic lesions and the liver were significantly greater on hepatic artery dominant phase scans (28 +/- 10 H) than on portal vein dominant phase scans (10 +/- 8 H), whereas the mean difference in enhancement between the exophytic lesions and the liver was statistically greater during the portal vein dominant phase (p < .01). Two of the hilar cholangiocarcinomas were resectable at surgery, and 18 were not. The overall accuracy of helical CT for assessing resectability was 60%. In 10 (56%) of 18 patients, unresectable disease was correctly diagnosed with helical CT (sensitivity, 56%). Eight (44%) of 18 patients considered to have resectable tumors with helical CT had unresectable tumors at surgery. A resectable tumor was correctly diagnosed in two patients with helical CT.

CONCLUSION

Multiphasic helical CT can be used to detect and classify hilar cholangiocarcinomas. However, the exact proximal tumor extent along bile ducts tends to be underestimated with helical CT; therefore, helical CT is inaccurate for determining resectability.

Mucinous biliary cystadenocarcinoma containing gas bubbles secondary to duodenal invasion

Biliary cystadenocarcinoma is a rare, usually intrahepatic neoplasm. A case is described in which an intrahepatic cystadenocarcinoma invaded the duodenum. This resulted in intratumoral gas.

Adrenal adenomas and nonadenomas: assessment of washout at delayed contrast-enhanced CT

PURPOSE

To measure the changes in wash-in and washout of contrast material on contrast material-enhanced computed tomographic (CT) scans in patients with adrenal adenomas and nonadenomas.

MATERIALS AND METHODS

One hundred twenty-two patients with 135 adrenal masses (74 adenomas, 61 nonadenomas) underwent helical CT. Unenhanced CT was followed by enhanced CT at 30, 60, and 90 seconds and 3, 10, and 30 minutes.

RESULTS

The adenomas enhanced significantly more than the nonadenomas at 60 seconds (P < .001), but the percentage enhancement of the adenomas was significantly greater than that of the nonadenomas at 30, 60, and 90 seconds (P < .001). At 3, 10, and 30 minutes, the absolute percentage loss of enhancement and the relative percentage loss of enhancement were significantly greater for the adenomas than for the nonadenomas (P < .001). Delayed enhanced CT at 10 minutes (sensitivity, 92%; specificity, 95%) and 30 minutes (sensitivity, 97%; specificity, 100%) was more accurate for differentiation of adenomas and nonadenomas than unenhanced CT (sensitivity, 82%; specificity, 95%).

CONCLUSION

Adrenal adenomas exhibit greater washout of contrast material than do adrenal nonadenomas. The percentage change in washout of contrast material is a useful adjunct to absolute CT attenuation values in differentiation of adrenal adenomas and nonadenomas.

Detection of pulmonary nodules with helical CT: comparison of cine and film-based viewing

OBJECTIVE

The purpose of our study was to determine whether cine viewing of helical CT scans of the chest improves the detection of pulmonary nodules in patients with known extrathoracic malignancy.

SUBJECTS AND METHODS

Identical helical CT studies of the chest of 60 patients with known extrathoracic malignancy were reviewed for detection of pulmonary nodules. Four radiologists interpreted the helical CT studies. Pulmonary nodules were divided into four groups according to maximum diameter: group 1, nodules smaller than or equal to 5 mm; group 2, nodules larger than 5 mm but smaller than or equal to 10 mm; group 3, nodules larger than 10 mm but smaller than or equal to 20 mm; group 4, nodules larger than 20 mm. Interpreters also assigned a lesion conspicuity score of pulmonary nodules based on a four-point scale: one point for poor visibility, two points for adequate visibility, three points for good visibility, and four points for excellent visibility. Static film-based images printed on a laser printer were viewed on a light box. Cine viewing of helical CT scans from the same examinations was done on a commercially available workstation. The number, diameter, and conspicuity scores of pulmonary nodules detected at lung window settings were documented.

RESULTS

Interpreters saw 266 nodules on cine viewing, whereas 237 nodules were seen with static film-based viewing. A significantly higher percentage of nodules that were smaller than or equal to 5 mm in diameter was found with cine viewing (n = 106) than with static film-based viewing (n = 81) (p < .05). Cine viewing (n = 105) also allowed a slightly but not significantly higher detection rate of nodules that were larger than 5 mm but smaller than or equal to 10 mm in diameter than did static film-based viewing (n = 101). We found no differences between cine (n = 55) and static film-based viewing (n = 55) in the detection of pulmonary nodules that were larger than 10 mm in diameter. The mean conspicuity score of nodules was significantly higher with cine viewing (2.9 +/- 0.2) than with film-based viewing (2.4 +/- 0.2) (p < .05).

CONCLUSION

Cine viewing of helical CT scans significantly increases the detection rate of pulmonary nodules that are smaller than or equal to 5 mm in diameter. However, we found no significant difference between cine and film-based viewing in the detection rate of pulmonary nodules that were larger than 5 mm in diameter. The advantages of cine viewing may be attributed to both the larger image size and the ability to scroll through images for improved differentiation between vessels and nodules.

CT-anatomy of the nasolacrimal sac and duct

Recent developments in ophthalmology such as balloon dilatation, stent implantation, laser therapy and endoscopy of the lacrimal drainage system raise the need for a detailed anatomical knowledge of this system. In this study morphometric measurements of the lacrimal drainage system were performed with thin-section axial computed tomography (CT) examinations in 147 patients with no signs of pathology related to the lacrimal drainage system. The mean length of the nasolacrimal duct measured 11.2 +/- 2.6 mm (range: 6-21 mm), the narrowest diameter was 3.7 +/- 0.7 mm (range: 2-7 mm). The mean length of the nasolacrimal sac was 11.8 +/- 2.5 mm (range: 6-18 mm). The width of the nasolacrimal sac did not exceed 4 mm unless filled with air. In 43 (29.3%) of the subjects air was visible within the nasolacrimal sac or duct. The knowledge of the morphometry of the lacrimal drainage system enables the ophthalmologist to plan intervention on the lacrimal drainage system precisely and avoid unnecessary manipulations.

Functional magnetic resonance imaging of human renal allografts during the post-transplant period: preliminary observations

Graft dysfunction is a common occurrence during the first weeks following renal transplantation. The current study was designed to evaluate the potential of renal magnetic resonance (MR) perfusion imaging to differentiate acute allograft rejection (AAR) from acute tubular necrosis (ATN) during the post-transplant period. Twenty-three consecutive patients with clinically suspected ATN and/or AAR and eight consecutive control patients (asymptomatic, serum creatinine concentration < 1.5 mg/dL) underwent MR perfusion imaging of the renal allograft within 64 days after transplantation. Histopathology was obtained in all cases with clinical suspicion of ATN or AAR. Sixty sequential fast gradient-recalled-echo MR images were acquired in each patient after intravenous administration of gadolinium-DTPA (0.1 mmol/kg). Histopathology revealed 6 patients with pure AAR, 4 patients with a combination of AAR and ATN, 12 patients with ATN and 1 patient with normal findings. Kidney graft recipients with normal renal function showed a moderate increase in signal intensity (SI) of the renal cortex and medulla after administration of contrast agent followed by an immediate and short decrease in SI of the medulla (biphasic medullary enhancement pattern). The increase in cortical SI of patients with AAR was significantly smaller (61 +/- 4% increase above baseline) than that measured in normal allografts (136 +/- 9% increase above baseline) (p < 0.05) and patients with ATN (129 +/- 3% increase above baseline) (p < .05). Patients with ATN had a slightly delayed and diminished cortical enhancement and an uniphasic and lesser medullary enhancement pattern compared to that observed in normal allografts (p < 0.05). A close correlation (r = 0.72) was found between serum creatinine concentration levels and changes in SI. Thus, MR imaging results and histopathology were in agreement in 22 of 23 patients (96%). MR perfusion imaging of renal allografts can be used to noninvasively differentiate ATN from AAR during the post-transplant period, and may also be helpful in cases were covert AAR is superimposing ATN during a phase of anuria. Patients with ATN can be separated from normals in the majority of cases as reflected by an uniphasic medullary enhancement pattern.

Magnetic resonance imaging of Achilles tendon in patients with rheumatoid arthritis

RATIONALE AND OBJECTIVES

The authors characterize the appearance of the Achilles tendon in patients with rheumatoid arthritis and differentiate this appearance from degenerative tendinopathy in patients with chronic pain of the heel using magnetic resonance (MR) imaging.

METHODS

Thirty patients with rheumatoid arthritis and 28 patients with chronic pain of the heel underwent MR imaging of the ankle and foot. Three radiologists independently assessed the MR images with respect to size, shape, and intratendinal signal characteristics of the Achilles tendon. The Achilles tendon was considered abnormal on MR imaging when intratendinous signal alterations or an anteroposterior measurement greater than 8 mm was seen. Physical examination of the Achilles tendons was accomplished in both groups. Operation confirmed the diagnosis of 13 patients in the second group with chronic pain of the heel.

RESULTS

The Achilles tendon of 83% of patients with rheumatoid arthritis demonstrated various intratendinous patterns (longitudinal, reticular, nodular) of intermediate signal intensity on all pulse sequences on MR imaging. Ninety percent of patients with rheumatoid tendinopathy showed no enlargement of the anteroposterior diameter of the Achilles tendon. In addition, all patients with rheumatoid arthritis had findings compatible with an inflammation of the retrocalcaneal bursa on MR imaging, whereas none of the patients with tendinopathy associated with chronic heel pain had retrocalcaneal bursitis. All patients, however, had enlargement of the anteroposterior diameter of the Achilles tendon. Seventy-nine percent showed various intratendinous lesions of intermediate signal intensity on all pulse sequences. Twenty-one percent of patients had an enlargement of the Achilles tendon without intratendinous changes.

CONCLUSIONS

Rheumatoid tendinopathy can be distinguished from degenerative tendinopathy in patients with chronic pain of the heel with MR imaging. Inflammation of the retrocalcaneal bursa and the absence of enlargement of the tendon combined with the presence of intratendinous signal alterations are characteristic findings of rheumatoid tendinopathy.

Basilar tip aneurysm: endovascular treatment with Guglielmi detachable coils--midterm results

PURPOSE

To determine the safety and effectiveness of Guglielmi detachable coils in the endovascular treatment of ruptured and nonruptured basilar tip aneurysms.

MATERIALS AND METHODS

A basilar tip aneurysm was occluded with Guglielmi detachable coils in 21 patients. The aneurysmal diameter was small (less than 12 mm) in 15 patients, large (12-25 mm) in four patients, and giant (more than 25 mm) in two patients. Angiographic follow-up ranged from 6 to 48 months (mean, 26 months); clinical follow-up ranged from 1 to 48 months.

RESULTS

Embolization was technically successful in all patients. Complete occlusion was achieved in 14 (67%) patients; 90% occlusion was achieved in seven (33%) patients. There was partial reperfusion of the aneurysm in three patients (14%) after 6 months, which necessitated repeated embolization. The clinical results were excellent in 13 patients, good in six, and fair in one. One patient died 2 months after the embolization due to pulmonary complications. A posterior cerebral artery was occluded in five (24%) patients; one of these patients developed a permanent neurologic deficit, one developed a transient neurologic deficit, and three had no clinical symptoms.

CONCLUSION

Endovascular treatment of a basilar tip aneurysm with Guglielmi detachable coils seems to be a safe and less invasive alternative to surgical clipping.

Posttraumatic extracranial aneurysm of the internal carotid artery: combined endovascular treatment with coils and stents

We report a case of a posttraumatic extracranial pseudoaneurysm of the internal carotid artery that was treated successfully via embolization with Guglielmi detachable coils and placement of a Wallstent after surgical repair failed.

[Benign non-organ-related diseases of the retroperitoneal space]

Because of the anatomic localisation of the retroperitoneal space, the detection and elucidation of pathology in the retroperitoneum calls for clinical acumen and the utilisation of imaging techniques. During the past two decades, efforts spearheaded by the work of M. A. Meyers led to an enhanced understanding of retroperitoneal anatomy and pathology. Conventional radiographic techniques are often incapable of detecting and/or characterising retroperitoneal abnormalities. Sonography may be limited by patient-dependent-factors. CT is unaffected by bowel gas and provides discrete cross-sectional images of the organs, fascial planes and retroperitoneal compartments, making it an ideal tool for assessment of retroperitoneal disease. In clinically stable patients MRT may be a useful modality for providing helpful and additional information in characterising retroperitoneal abnormalities. In this review article the diagnostic possibilities of benign not organ-related diseases of the retroperitoneum are described. This is intended to give the reader an insight into the etiology and distribution patterns of retroperitoneal fluid and gas collections as well as into diagnosis and differential diagnosis of benign retroperitoneal diseases. The diagnostic impact of the different imaging modalities is discussed.

Quantification of area at risk during coronary occlusion and reperfusion by means of MR perfusion imaging

PURPOSE

Considerable clinical interest has focused on the size of ischemic myocardium. Fast MR imaging in conjunction with MR contrast media has the potential to identify hypoperfused and infarcted myocardium. This study used MR perfusion imaging to detect and quantify reperfused ischemic myocardium during a brief coronary occlusion and reperfusion, and to characterize the spatial extent of ischemic and reperfused ischemic myocardium relative to the "true" size of the area at risk as defined in histochemical morphometry at post mortem.

MATERIAL AND METHODS

The left circumflex (LCX) coronary artery in 8 dogs was occluded for 15 min followed by reperfusion in order to produce regional reversible myocardial ischemia. Perivascular Doppler probes were used to measure blood flow in the left anterior descending (LAD) and LCX coronary arteries. Fast inversion recovery-prepared gradient-recalled-echo images were acquired to delineate the ischemic area during occlusion, and the area of reversible ischemic injury at 1 and 30 min of reperfusion. The size of ischemic and reperfused ischemic myocardium were compared with the area at risk as determined by histochemical morphometry at post mortem.

RESULTS

During LCX occlusion, LCX flow decreased from 16+/-1 to 0.2+/-0.1 ml/min. On contrast-enhanced images, ischemic myocardium was evident as a zone of relatively low signal intensity (SI) compared to normal myocardium. The size of the ischemic region was significantly smaller (30+/-2%) than at post mortem (36+/-3%; p<0.05). Immediately after reperfusion, LCX flow increased to 83+/-11 ml/min and the contrast medium caused greater enhancement in the reperfused ischemic region than in the normal myocardium (69+/-3 vs 42+/-3 arbitrary units; p<0.05). The increase in regional SI correlated closely with the increase in regional blood flow (r=0.73). At 1 min of reperfusion, the size of the reperfused ischemic myocardium was larger (48+/-3%, p<0.05) than the area at risk measured at post mortem. At 30 min of reperfusion, when the flow returned to baseline values (16+/-2 ml/min), contrast bolus produced no differential enhancement between the 2 myocardial territories.

CONCLUSION

MR perfusion imaging has the potential to detect and quantify the size of ischemic myocardium and the region of post-occlusive hyperemia in the early reperfusion period. There is a significant direct linear relationship between the regional contrast enhancement of reperfused ischemic myocardium and the blood flow during post-occlusive hyperemia. The difference in the size of the area at risk at MR perfusion imaging and at histochemical morphometry may reflect an influence of coronary collateral circulation.

Endovascular treatment of renal artery aneurysms with conventional non-detachable microcoils and Guglielmi detachable coils

OBJECTIVE

To evaluate the efficacy and safety of endovascular occlusion of true renal artery aneurysms (RAAs) with conventional non-detachable microcoils (NDCs) and Guglielmi detachable coils (GDCs).

PATIENTS AND METHODS

Over a 5-year period, 12 RAAs were treated by endovascular selective embolization. Four RAAs were occluded using NDCs and eight were treated with GDCs. All coils were delivered through a microcatheter. Eight RAAs were located in the bifurcation of the main renal artery, two in the main renal artery and two were intrarenal. Before treatment, four patients presented with hypertension, one associated with renal infarction and a second had flank pain due to microembolization. Two other patients had renal infarction, associated with haematuria in one; one other patient also had haematuria and five patients were asymptomatic. All patients were followed using clinical and angiographic examinations after 6 months, 1 and 2 years.

RESULTS

All RAAs were occluded successfully. In two patients treated with NDCs there were minor complications, i.e. one subsegmental peripheral infarction and one misembolization, both without clinical symptoms. In the group treated with GDCs there were no complications. Five of seven patients were clinically improved, while two patients remained clinically unchanged.

CONCLUSION

Superselective endovascular treatment of RAAs with microcoils is a safe, efficient, and less invasive alternative to surgical treatment. The high flexibility and softness of the GDC and the controlled detachment enables a safer and more complete occlusion of RAA than current alternatives.

Quantification of coronary artery volume flow rate using fast velocity-encoded cine MR imaging

OBJECTIVE

Breath-hold velocity-encoded cine (VENC) MR imaging has been proposed as a method for measuring coronary blood flow. However, most studies have measured velocity rather than volume flow rate in the coronary arteries. The purpose of this study was to measure volume flow rate in the coronary artery of dogs using high-speed gradients and to compare MR flow measurements with those obtained with a sonographic flowmeter.

MATERIALS AND METHODS

Fast VENC MR images were obtained with a high-speed-gradient 1.5-T MR system in seven anesthetized dogs before and after administration of dipyridamole. Images were acquired on double oblique planes perpendicular to the left anterior descending arteries with a slice thickness of 5 mm, a field of view of 20 x 10 cm, a velocity window of +/- 1 m/sec, an average imaging time of 21 sec, a TR/TE of 11/5, and a temporal resolution of 44 msec.

RESULTS

Coronary flow measured with VENC MR imaging correlated well with flow measured by the flowmeter (r = .95, slope = 0.97, n = 88). Interobserver variability in measuring coronary flow volume was 8%.

CONCLUSION

Fast VENC MR imaging with high-speed gradients can provide accurate quantification of volume flow rate in coronary arteries.

Quantitative CT evaluation of adrenal gland masses: a step forward in the differentiation between adenomas and nonadenomas?

PURPOSE

To assess the attenuation of the adrenal gland with computed tomography (CT) before and after multiple phases of contrast enhancement in both control subjects and patients with adenomas and nonadenomas.

MATERIALS AND METHODS

Seventy-two patients with 78 adrenal masses (41 adenomas, 37 nonadenomas) underwent helical CT. Forty subjects served as controls. Unenhanced CT was performed followed by enhanced CT at 30, 60, 90, and 180 seconds and 30 minutes.

RESULTS

At unenhanced CT, mean attenuation was 4 HU +/- 16 for adenomas compared with 37 HU +/- 12 for the nonadenomas (P < .001) and 24 HU +/- 3 for normal glands. Although the mean attenuation of nonademonas was significantly greater than that of adenomas on 60- and 90-second scans (P < .001), there was greater overlap in attenuation of the adenomas and nonadenomas than on unenhanced images. At 180 seconds, nonadenomas had higher attenuation than adenomas (73 HU +/- 17 vs 41 HU +/- 18; P < .001). At 30 minutes, all adenomas had attenuation less than 37 HU, whereas all nonadenomas had attenuation greater than 41 HU.

CONCLUSION

Delayed-enhanced CT scans obtained 30 minutes after administration of contrast material can enable differentiation of adenomas and nonadenomas.

[Endovascular embolization treatment for intractable epistaxis]

BACKGROUND

Intractable epistaxis has been treated with surgical intervention for many years, including ligation of the internal maxillary artery. As an alternative approach, endovascular therapy has gained increased acceptance. The purpose of our study was to evaluate the efficacy and safety of endovascular treatment of untractable epistaxis.

METHODS

Embolotherapy was performed in 26 patients. The indication for embolization was persistent epistaxis even after anterior and posterior nasal packing. In all but two patients, who required general anesthesia, the procedure was performed in local anesthesia. Endovascular embolization of the internal maxillary artery was performed by using microcatheters, which were introduced intraarterially. Particulate embolic agents were used in all but one patient, who was treated by means of minicoils.

RESULTS

The embolization of the territory of the internal maxillary artery was possible in all cases, the technical success rate was 96%, the clinical success rate was 100%. No complications were encountered. Because of an acute recurrent bleeding in one case, a second embolization was performed. No delayed hemorrhages were noted.

CONCLUSIONS

Endovascular embolotherapy seems to be an excellent, safe, and less invasive alternative to surgery in patients with intractable epistaxis.

Multiphasic helical CT of the kidney: increased conspicuity for detection and characterization of small (< 3-cm) renal masses

PURPOSE

To evaluate the potential of thin-section multiphasic helical computed tomography (CT) in the detection and characterization of small (< 3.0-cm) renal masses.

MATERIALS AND METHODS

Identically collimated helical CT of the kidney was performed before and after administration of contrast material in 93 patients with small renal masses. Helical CT scans were obtained during the corticomedullary and nephrographic phases. Differences between attenuation of the lesion and that of the kidney were measured quantitatively. The presence of a mass or absence of disease was confirmed with clinical, imaging, and histologic findings.

RESULTS

The number of masses smaller than 3.0 cm detected on corticomedullary-phase scans (n = 211) was statistically significantly fewer than those on nephrographic-phase scans (n = 295) (P < .01). Mean differences in enhancement between the renal cortex and masses were 148 HU +/- 54 and 137 HU +/- 44 during the corticomedullary and nephrographic phases, respectively, and the difference in attenuation of the renal medulla and that of the masses was statistically significantly greater during the nephrographic phase (P < .01). False-positive results (n = 9) occurred only on corticomedullary-phase scans because of lack of enhancement of the renal medulla.

CONCLUSION

Nephrographic-phase scans enabled greater lesion detection and better characterization of small renal masses than corticomedullary-phase scans. Nephrographic-phase scans should be obtained when only monophasic scanning is used to detect small renal masses.

Extracranial aneurysm and arteriovenous fistula: embolization with the Guglielmi detachable coil

PURPOSE

To evaluate the feasibility and safety of Guglielmi detachable coils for endovascular treatment of extracranial aneurysm and arteriovenous fistula.

MATERIALS AND METHODS

Embolization with Guglielmi detachable coils delivered through Tracker-18 microcatheters was performed in 16 patients. This patient group had eight renal artery aneurysms and 11 arteriovenous fistulas (three cases of patent ductus arteriosus, one associated with aneurysm; one fistula between the maxillary artery and jugular vein; two fistulas between the subclavian and pulmonary arteries; four fistulas between the pulmonary artery and vein; and one fistula between the anterior tibial artery and vein). Efficacy of the procedure was assessed by means of short-term follow-up (clinical examination, angiography, and/or Doppler sonography) 3 and 6 months later.

RESULTS

No complications were encountered. Embolization was technically and clinically successfully in all eight aneurysms (100%) and in nine arteriovenous fistulas (82%). In two cases (fistula between the subclavian and pulmonary arteries and fistula between the anterior tibial artery and vein) endovascular placement of Guglielmi detachable coils failed to occlude the vessel. Results of short-term follow-up examinations confirmed the initial results in all cases.

CONCLUSION

Guglielmi detachable coils are feasible, safe, and effective for endovascular treatment of extracranial aneurysm and arteriovenous fistula.

[Magnetic resonance tomography in myocardial ischemia: state of the art]

Recent developments in MR imaging have opened up new avenues in the investigation of ischaemic heart disease. Conventional unenhanced spin-echo sequences have been used to detect and quantify myocardial infarction. Along with the technical advances aimed at reducing motion artifacts and imaging time, the advent of contrast media for MR imaging has further strengthened its diagnostic capacities. The applications of MR contrast media are increasing, and they are becoming more specific, to enable differentiation of occlusive and reperfused myocardial infarctions and to discriminate between reversible and irreversible myocardial injury. Previous studies have also indicated that dual administration of both relativity-based and susceptibility-based contrast media can be used to determine whether viable myocardium is present in the reperfused ischaemic area. Magnetic susceptibility MR contrast media have the potential to demonstrate a region of the ischaemically injured myocardium in which myocardial necrosis is present. A cornerstone in the MR assessment of ischaemic heart disease has been achieved with the advent of fast MR imaging techniques. Ultrafast gradient-recalled-echo sequences or echo-planar imaging allow to monitor the first passage of the contrast medium through the heart. With the aid of MR contrast media, these techniques may be useful in estimating regional myocardial perfusion and blood volume. Experimental and clinical perfusion studies indicate that perfusion-sensitive MR imaging, particularly in concert with coronary vasodilators, can detect compromised myocardium. Combining myocardial perfusion imaging with the anatomic and functional information provided by other MR imaging techniques such as cine and velocity-encoded sequences could make MR imaging a comprehensive noninvasive diagnostic tool for the assessment of ischaemic heart disease.

Vascular complications in lumbar disk surgery: report of four cases

Vascular injuries in lumbar disk surgery, although rare, are serious complications which may be overlooked due to a broad range of clinical manifestations. It is important that surgeons and radiologists be aware of these potentially fatal complications and develop an appropriate symptom-based diagnostic paradigm. We reviewed 8099 consecutive cases of lumbar disk surgery, performed over a 14-year period at a single institution, for postoperative vascular complications. We identified four patients (0.05%) with lumbar disk surgery-related vascular complications: intraoperative lacerations of the abdominal aorta and median sacral artery, an arteriovenous fistula between the left common iliac artery and vein detected 19 days postdiskectomy, and a partially thrombosed aortic aneurysm with an arteriovenous fistula between the aneurysm and the inferior vena cava, diagnosed 11 months after surgery. The majority of cases in the literature of vascular injury in lumbar disk surgery were reported prior to 1965. Diagnostic approaches described in that period do not reflect the great range of diagnostic techniques available today. Angiography remains the gold standard for diagnosis and guidance as to surgical repair. However, a high index of suspicion based on clinical signs and/or the use of sonography or CT is important in the detection of these complications.

MR imaging characterization of postischemic myocardial dysfunction ("stunned myocardium"): relationship between functional and perfusion abnormalities

Stunned myocardium has been detected in patients treated successfully with thrombolytic agents. The hypothesis of this study was that fast gradient echo (GRE) imaging could be used to characterize the regional functional and perfusion abnormalities that are indicative of myocardial stunning. This study was designed to monitor and correlate the extent of wall thickness and perfusion abnormalities as determined by fast (segmented k space) cine and contrast enhanced GRE imaging, respectively. Dogs were subjected to left circumflex (LCX) coronary artery occlusion (15 min) followed by 30-minute reperfusion (n = 8). Perivascular flow probes were used to continuously measure flow in left anterior descending (LAD) and LCX coronary arteries. Short-axis inversion recovery prepared fast GRE and cine images were acquired at baseline, at occlusion, and at 1, 10, and 30 minutes of reflow. Regional signal intensity and percent systolic wall thickening were determined at 26 equally spaced circumferential positions to compare the extent of functional and perfusion abnormalities. During occlusion and reperfusion, the ischemic region was demonstrated on contrast-enhanced images as a hypointense and hyperintense region, respectively. During occlusion, the extent of the perfusion defect (32% +/- 2% of the circumference of the equatorial slice) correlated closely (r = .74) with the extent of contractile dysfunction (35% +/- 2%). After reperfusion, there was transient recovery in the percent wall thickening (26% +/- 4% vs 36% +/- 4% normal), coinciding with the reactive hyperemic response, but this was followed by a significant decline in wall thickening at 10 minutes (19% +/- 4%) and 30 minutes (12% +/- 2%). Fast MR imaging may be useful to monitor postischemic myocardial abnormalities after thrombolytic therapy and the response to pharmacologic interventions.

Coronary flow reserve: noninvasive measurement in humans with breath-hold velocity-encoded cine MR imaging

PURPOSE

To measure coronary vasodilator reserve with breath-hold velocity-encoded cine magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Eight healthy adult volunteers underwent 1.5-T MR imaging. Velocity-encoded cine images were acquired at seven to 13 temporal phases in 25 seconds, with k-space segmentation and view-sharing reconstruction (+/- 1 m/sec velocity-encoding value) (repetition time msec/echo time msec = 16/9). Flow velocity in the left anterior descending (LAD) artery was measured twice before and twice after administration of dipyridamole (0.56 mg per kilogram of body weight).

RESULTS

Peak diastolic coronary flow velocity in the LAD artery was 14.8 cm/sec +/- 1.9 (mean +/- standard deviation) in the baseline state. It increased significantly (P< .01) to 46.3 cm/sec +/- 10.2 after dipyridamole administration, with an average coronary reserve of 3.14 +/- 0.59. Interstudy and interobserver reproducibilities for measurement of peak diastolic velocity were, respectively, 9.5% +/- 1.6 and 7.0% +/- .2.5 in the baseline state and 6.8% +/- 2.2 and 3.4% +/- 1.5 after dipyridamole administration.

CONCLUSION

Breath-hold velocity-encoded cine MR imaging provided reproducible assessment of coronary flow reserve in humans.

Ultrafast computed tomography and three-dimensional image processing of CT sialography in patients with parotid masses poorly defined by magnetic resonance imaging

The purpose of this study was to determine the efficacy of ultrafast computed tomography (UF CT) in patients with parotid masses poorly defined by magnetic resonance imaging (MRI) and to evaluate the diagnostic potential of three-dimensional (3-D) UF CT sialography when compared with conventional CT sialograms. Thirteen patients with clinical suspicion of a parotid mass, in whom MRI was degraded by motion, underwent UF CT of the parotid region. Two radiologists independently assessed the CT and MR with respect to tumor localization, intraglandular tumor location, tumor margin characteristics, and infiltration of surrounding tissue. In 9 patients, CT sialography was performed using 3-D image processing. Anatomical details and pathologic findings were assessed by three readers using a numerical grad and compared with the findings derived from conventional CT sialography. Histopathologic specimens were obtained in all cases and correlated with the radiographic findings in a consensus manner following the blinded interpretations. UF CT and (suboptimal) MRI provided the same diagnostic information for the evaluation of tumor localization, and intraglandular location. UF CT was superior to MRI in the detection of tumor infiltration, and definition of tumor margins in 2 cases (15%), resulting in a substantial difference in treatment. Three-dimensional CT sialography offered significant improvement in demonstration of anatomic detail (2.5 +/- 0.2 vs 1.5 +/- 0.1, respectively) and pathologic findings (2.6 +/- 0.1 vs 1.3 +/- 0.2, respectively) when compared with conventional CT sialography. UF CT is a viable alternative in uncooperative patients with parotid masses. UF CT 3-D sialography has the potential to allow more precise pre-surgical planning and contributes to the diagnosis and therapy planning of parotid masses.

Cardiovascular applications of magnetic resonance flow and velocity measurements

With recent developments of MR techniques for blood flow measurements, qualitative and quantitative information on both flow volume and flow velocity in the major vessels can be obtained. MR flow quantitation uses the phase, rather than the amplitude of the MR signal, to reconstruct the images. Previous validation studies have demonstrated the accuracy of the phase shift techniques for measuring flow velocities. This technique is now being applied successfully in the cardiovascular system to quantify global and regional ventricular function, valvular heart disease, pulmonary artery disease, thoracic aortic disease, congenital heart disease, and ischemic heart disease.

Three-dimensional processing of ultrafast CT sialography for parotid masses

PURPOSE

To evaluate the diagnostic potential of three-dimensional image processing of ultrafast CT sialography in comparison with conventional CT sialography in patients with parotid masses.

METHODS

In nine patients, CT sialography was done with three-dimensional image processing. The visibility of anatomic details and pathologic findings, derived from three-dimensional images, were graded numerically by three observers and compared with the findings obtained from conventional CT sialograms. Histopathologic specimens were obtained in all cases.

RESULTS

Ultrafast CT images showed no motion artifact. Three-dimensional CT sialography offered significant improvement in demonstration of ductal anatomy (2.5 +/- 0.2 versus 1.5 +/- 0.1, respectively) and ductal pathology (2.6 +/- 0.1 versus 1.1 +/- 0.2, respectively) over conventional CT sialography. In two cases, the therapeutic regimen was altered substantially.

CONCLUSION

Ultrafast CT three-dimensional sialography has the potential to allow more precise presurgical planning and contributes to the diagnosis and therapy planning of parotid masses, especially in patients in whom MR image quality is degraded by motion artifact.