Analysis of radiology education in undergraduate medical doctors training in Europe

Objectives

The purpose of the present study is to describe how undergraduate radiology teaching is organized in Europe and to identify important characteristics of undergraduate radiology curriculum.

Methods

An electronic survey on undergraduate teaching was distributed by the European Society of Radiology (ESR) to 38 national delegates of the ESR Education Committee.

Results

The “classic type” of radiology teaching method is more frequent than the “modular type”. In 38% of medical training centres the first experience with radiology is in pre-clinical years. The students enrolled in the fourth medical year experience the largest involvement in radiology education. The total number of teaching hours (mean 89 h, median 76 h) varies across the countries and differs depending on the radiological topic (mean across all topics 14.8 h, median 13). Written tests and oral exams were the most frequently used examination modes. Clerkships are reported as a key part of training.

Conclusion

This first international comparative study of undergraduate radiological curriculum in Europe identifies a large number of differences in curriculum content and teaching methods throughout Europe. More research is needed to establish the radiological educational competences resulting from these differing curricula's to improve and to standardize the teaching according to (inter)national and institutional needs.     

Patient-reported outcomes of prostate high-dose-rate brachytherapy boost comparing an outpatient and inpatient protocol: a two-center chronologic cohort study

Purpose

To determine patients’ self-reported experiences of outpatient high-dose-rate prostate brachytherapy boost, and compare with previous cohort treated as inpatients.

Methods and Materials

Using the Prostate Brachytherapy Questionnaire, we previously examined patients’ subjective experience of the brachytherapy procedure when it involved one implant and hospitalization with the template in situ for 2 days (Group 1). The protocol was subsequently changed to two implants, 2 weeks apart as outpatients. Fifty-eight patients treated with the new protocol (Group 2) completed the same questionnaire. We compared the self-reported experiences between Groups 1 and 2 and also between the first and second implant for those in Group 2. Our hypothesis was that the worst rated issues in Group 1 might be reduced with the new approach.

Results

Group 2 patients were less troubled overall by the procedure (mean scores 2.3 vs. 3.2, p = 0.0293). Specifically, they were less troubled by “discomfort” (2.8 vs. 3.8, p = 0.0254); “being stuck in bed” (1.7 vs. 4.2 p < 0.0001); “feeling helpless” (1.3 vs. 2.8, p = 0.0009); “fear of opening my bowels” (2.1 vs. 3.3, p = 0.0055); and “fear of coping with the implant” (1.3 vs. 2.5, p = 0.0004). There was no significant increase in “thought of implant” or “fear of implant” before the second implant. However, more patients rated worse than expected “fear of passing urine” during the second implant.

Conclusions

Patients rated high-dose-rate brachytherapy less troublesome when delivered as outpatient with two implants, 2 weeks apart than as inpatient over 3 days, despite the additional invasive procedure and anesthesia.     

Single-centre review of radiologically guided percutaneous nephrostomy using "mixed" technique: success and complication rates

Aim

A review of complication and success rates of the “mixed” technique in percutaneous nephrostomy using both the Seldinger and one-step techniques in dilated and non-dilated systems.

Materials and methods

We retrospectively analysed 500 percutaneous nephrostomies in dilated an non-dilated systems in 353 patients from 2006 to 2007 (208 males (range 19-95 years), 127 females (range 27-91 years) and 21 children (range 3 months-16 years: 6 females, 15 males)). Percutaneous nephrostomy was considered successful if catheter was placed in renal pelvis and drained urine spontaneously. Successful percutaneous nephrostomies were classified as primary (renal system drained instantly) or postponed (drainage achieved within 24 h after initial failure). Number of complications was registered.

Results

All of the 500 nephrostomies were successful within 24 h (96.2% primary; 3.8% postponed). The success rate of primary nephrostomy in dilated and non-dilated systems was 98.2% and 82%, respectively. Major complications occurred in 0.45% and minor complications in 14.2%.

Conclusion

Percutaneous nephrostomy using the “mixed” technique is very successful in dilated systems, is not superior to other PCN techniques in non-dilated systems and has a very low rate of major complications.     

Cost implications of initial computed tomography angiography as opposed to catheterization in patients with mildly abnormal or equivocal myocardial perfusion scans

Background

Patients with mildly abnormal or equivocal myocardial perfusion imaging (MPI) scans undergo diagnostic angiography or receive medical management. However, current guidelines mandate different treatment goals for patients with known coronary artery disease (CAD), and catheterization is often required. Coronary computed tomography angiography (CCTA) may be an effective alternative to catheterization for patients at intermediate risk for CAD.

Objectives

The purpose of this study was to analyze the cost implications of CCTA before catheterization in patients with mildly abnormal or equivocal MPI scans.

Methods

Patients (n = 206) with mildly abnormal or equivocal MPI scans underwent 64-detector CCTA instead of catheterization at the discretion of a treating physician. Studies were evaluated by a trained reader, and results were classified as “no evident CAD,” “nonobstructive CAD,” or “potentially obstructive CAD.” Cost data were analyzed based on actual reimbursements for CT angiography and cardiac catheterization. We modeled the costs of two clinical approaches. “Selective catheterization” involved catheterization only if CCTA showed potentially obstructive CAD. “Immediate catheterization” considered catheterization for all patients in the cohort. Sensitivity analysis was performed on multiple variables.

Results

Thirty-two percent of patients had potentially obstructive plaque on CTA. Selective catheterization saves $1454 per patient. Sensitivity analysis revealed cost savings to be preserved even if up to 81.5% of the patient cohort undergoes catheterization, as well as across wide ranges of procedural costs.

Conclusion

A strategy that uses CCTA as a gatekeeper to catheterization is cost saving as opposed to initial catheterization for patients with equivocal or mildly abnormal myocardial perfusion scans.     

Left anterior descending coronary artery myocardial bridging by multislice computed tomography: Correlation with clinical findings

Objective

To assess the relationship between left anterior descending (LAD) coronary artery myocardial bridging detected by 64-slice computed tomography (CT) and clinical findings.

Methods

221 consecutive patients were examined with coronary 64-slice CT angiography. 21 patients with coronary stenosis >50% were excluded. The length, depth, and luminal narrowing of LAD myocardial bridges during systole and diastole were measured. CT findings were compared with the treadmill ECG-stress test, and clinical symptoms.

Results

Myocardial bridges of the LAD were found in 23% of patients (51/221) (length, 14.9 ± 6.5 mm; depth, 2.6 ± 1.6 mm). A significant difference was noted between the LAD luminal diameter before the intramyocardial course and intramyocardially, for both diastole and systole (p < 0.001); with a higher diameter reduction of 27% for end-systole compared to end-diastole with 15% (p = 0.006). Systolic LAD intramyocardial luminal narrowing >50% was found in 3/25 (8%). 30/51 (59%) of bridges were “deep” (>2 mm myocardial depth), 21/51 (41%) were “superficial”. The prevalence of a positive ECG-stress tests for the anterior myocardial region was significantly higher in patients with LAD myocardial bridges (34/50; 68%) compared to those without (28/144; 19.4%) (p < 0.001). There was no difference between “superficial” and “deep” LAD myocardial bridges in regard to a positive treadmill ECG-stress test. Typical angina was rare with 6%.

Conclusion

LAD myocardial bridges are common findings and can possibly explain a positive exercise ECG-stress test for anterior myocardial ischemia. Intramyocardial LAD segments show mild-to-moderate luminal narrowing at rest, which is higher during end-systolic phase.     

A pilot study to evaluate the use of virtual lectures for undergraduate radiology teaching

Purpose

To demonstrate that virtual lectures can substitute conventional lectures in radiology education for medical students.

Methods and materials

During the course 2005–2006, 89 out from 191 (46.6%) third year students of a subject entitled “General Radiology”, participated voluntarily in a pilot study including 22 virtual lectures (Flash presentations translated from the same PowerPoint presentations of conventional lectures, adding recorded narration and navigation tools). Participants (P) studied by means of virtual lectures, while non-participants (NP) assisted to conventional lectures.The results of the final oral exam classified from 0 to 3, and a 60-questions evaluation on image interpretation were used to compare both groups after training. Finally, 34 students from the group P (38.2%) fulfilled a 10-points scale quality survey about the project.

Results

Final exam qualifications were significantly higher for P than for NP (2.11 ± 0.85 versus 1.73 ± 1.04) as well as the number of correct answers of the evaluation on image interpretation (24.2 ± 6.2 versus 21.2 ± 5.4), but differences could obey to different attitudes between both groups. The usefulness of virtual lectures to learn General Radiology obtained the highest global scoring (8.82 ± 1.00). Contents were generally better evaluated than the design of the presentations.

Conclusion

Virtual lectures can substitute conventional lectures in radiology education for medical students with no detriment to students’ learning. Their potential advantage is that magisterial lectures can be used to discuss contents with students in a more participative way if virtual lectures are provided before.     

Radiology as seen by medical students

Purpose

To determine the impact of exposing medical students to medical imaging during the first year of the second cycle of medical school (DCEM1) on their perception of this medical specialty and the acquisition of its basic concepts.

Materials and methods

All students in the 2007-2008 graduation class entering into the first year of the second cycle of medical school were anonymously enrolled into this project that included pre-rotation and post-rotation questionnaires, theory classes followed by clinical rotations with clearly predetermined objectives.

Results

A total of 108 students were enrolled, with 70% being females. The parents of the students had a medical or paramedical profession in 46.3% of cases. Before the rotation, 61.6% of students perceived a difference between a hospital-based practice and private practice. Fifty-two percent of students had a clear idea of their professional future prior to the rotation. Five students (4.7%) believed prior to the rotation that it might have an impact on their professional future, versus 63% after the rotation (P < 0.0001). The students whose parents work in the medical or paramedical field do not have a better defined idea of their professional future; on the other hand, they have more interest for radiology (73.6% with high or very high interest versus 52.8%, P = 0.03). After the rotation, there was a significant increase in the number of students with high or very high interest for radiology (77.8% versus 66.7%, P = 0.023). A student noted that he would redirect his career to radiology. There was also a significant increase in the number of students perceiving a difference between a hospital-based practice and private practice (82.2% versus 61.6%, P = 0.003). With regards to radiology knowledge before and after the rotation, there was a significant increase of mean scores (P < 0.001). Eighty-eight percent of students were satisfied or very satisfied with the radiology rotation. Overall, the students believe that 70% of the objectives were achieved. The only criticism from the students was that the clinical instructors were overworked.

Conclusion

Early exposure of medical students to radiology increases their level of interest for the specialty and increases the perception of differences between a hospital-based practice and private practice. The overall knowledge of students about radiology was improved, but the workload of clinical instructors impaired the quality of the rotation.     

Clinical relevance and scope of accidental extracoronary findings in coronary computed tomography angiography: A cardiac versus thoracic FOV study

Objective

To assess the spectrum and clinical relevance of extracoronary findings in coronary CT angiography (CCTA), and to compare a small (cardiac) field of view (FOV) to a large (thoracic) FOV setting.

Material and methods

1084 consecutive patients (mean 57 years) with low-to-intermediate risk of coronary artery disease were enrolled. 542 CCTA scans were interpreted with small FOV (160-190 mm²) encompassing the cardiac region. In another 542 CCTA (patients matched for age and gender), read-out of an additional full FOV (>320 mm²) covering the thorax was performed. Clinical relevance of extracoronary findings was considered as either “significant” or “non-significant”. “Significant” findings were subclassified as either score 1: findings necessitating immediate therapeutic actions, or score 2: findings with undoubted clinical or prognostic relevance, requiring clinical awareness, follow-up or further investigations (non-urgent). “Non-significant” findings were assigned to either score 3: findings not requiring follow-up or further tests, or as score 4: irrelevant incidental findings.

Results

Significantly more patients with extracoronary findings were identified by using a full FOV with 43.2% (234/542) compared to a small FOV with 33.6% (182/542) (p = 0.001). Similarly, a higher total number of extracoronary findings (n = 394) was found on full FOV compared to small FOV (n = 250) (p < 0.001).The detection rate of clinically significant findings was higher by using full FOV compared to small FOV (25.6% versus 15.4%) (p < 0.001), out of those 2.2% versus 1.8% of findings required immediate actions (score 1), and 23.4% versus 13.6% (p = 0.0001), respectively were of clinical relevance (non-urgent, score 2). The rate of malign findings was 0.2%, and of acute pulmonary embolism 0.1%.More lung pathologies were observed by using full FOV compared to small FOV (22% versus 7%) (p < 0.0001), and the detection rate of intrapulmonary nodules increased by 2.1%. Prevalence of aortic valve calcification (n = 72) was 13.3%, out of those 7% had less than 2 cm² aortic valve orifice area.

Conclusions

The interpretation of extracoronary findings on CCTA scans is mandatory given high prevalence of clinically significant findings by using a full “thoracic” FOV.     

Retroperitoneal neoplasms within the perirenal space in infants and children: Differentiation of renal and non-renal origin in enhanced CT images

Purpose

To retrospectively demonstrate the specific CT findings of retroperitoneal neoplasms to diagnosis and differential diagnosis renal and non-renal tumors within the perirenal space in infants and children.

Materials and methods

We retrospectively reviewed the clinical data and CT images of 42 consecutive patients with surgically and pathologically proven retroperitoneal neoplasms within the perirenal space. The patients were divided into renal tumors group (n = 16) and non-renal tumors group (n = 26). The former included nephroblastoma (n = 15) and renal lymphoma (n = 1), while the latter included neuroblastoma (n = 12), retroperitoneal teratoma (n = 6), adrenal ganglioneuroma (n = 4), retroperitoneal lymphoma (n = 2), ectopic pheochromocytoma (n = 1) and adrenal cortical carcinoma (n = 1). The clinical information of these patients and the major CT imaging findings which were related to lesion localization in the two groups were compared and statistically analyzed using Pearson Chi-Square Test and Risk Estimate.

Results

The mean diameter of tumors was 9.82 ± 6.13 cm (n = 42 range: 2.3-32 cm). The demographic data and chief clinical symptoms between the renal tumor group and the non-renal tumor group showed no statistically significant differences (P > 0.05). 30.8% (8/26) of non-renal tumor patients presented elevated urinary vanillylmandelic acid (VMA) level, while no patient showed elevated VMA in renal tumor group (P < 0.05). Some CT imaging signs of the renal tumors including “crescent sign” (odds ratio, OR = 52), “beak sign” (OR = 84), “embedded organ sign” (OR = 84), and “prominent feeding artery sign” (OR = 36) showed significantly higher incidence when compared to the non-renal tumors (P < 0.001). The sign of “renal displacement and renal axis rotation” (OR = 0.059) was seen in 23 of 26 (88.5%) non-renal tumors, but in only 5 of 16 (31.3%) renal tumors (P < 0.001). The sign of “extra-renal central plane of tumor” (OR = 0.038) was displayed in 24 of 26 (92.3%) non-renal tumors, but in only 5 of 16 (31.3%) renal tumors (P < 0.001). The CT findings such as “pseudocapsule” (OR = 38.5), “necrosis and cystic change” (OR = 11.2), “vascularity” (OR = 16.867), “distant metastasis” (OR = 5.96), and “inferior vena cava tumor thrombus” which were thought to be characteristic of renal tumors were observed with significant higher incidence in renal tumors group than in the non-renal tumors group (P < 0.05); while CT signs of “irregular mass” (OR = 0.045) and “intratumoral calcifications” (OR = 0.065) were observed with lower incidence in renal tumors group than in the non-renal tumors group (P < 0.05).

Conclusion

The “crescent sign”, “beak sign”, “embedded kidney sign” and “renal arteries feeding” are the most specific CT signs suggestive of renal tumors and distinguish them from non-renal origin tumors within the perirenal space. Other CT signs, such as “pseudocapsule”, “hypervascular tumors” and “Inferior vena cava tumor thrombus”, when present, tumors of renal origin are strongly suggested. On the other hand, CT signs of “irregular mass”, “intratumoral calcifications”, and associated elevated urinary vanillylmandelic acid strongly suggest the non-renal tumors.     

High resolution MR for evaluation of lower urogenital tract malformations in infants and children: Feasibility and preliminary experiences

Introduction

This retrospective study aimed to assess the value of supplementing heavily T2-weighted, high resolution MR-imaging for detailed anatomic assessment in paediatric lower urogenital tract (UGT) malformations.

Patients/methods

Sixteen patients (6 male and 10 female, median age = 1.8 years, range = 0-9 years) with suspected malformations of the lower UGT who were retrospectively identified from the PACS underwent a clinically indicated standard MR-urography study. In order to facilitate a better anatomic assessment of questioned specific lower UGT structures, an additional three-dimensional Constructive Interference in Steady State-sequence (3D-CISS) had been acquired in these patients. The final diagnosis was established by all imaging results and surgical or laprascopic findings. The findings from the CISS-sequence were compared to the results from standard MR-urography for complementary anatomic information and conspicuity.

Results

Diagnostic 3D-CISS image quality was achieved in all patients. The 3D-CISS confirmed an ectopic ureteral insertion in six patients and reliably excluded ectopic insertion in 10 patients, whereas conventional MR-urography showed an ectopic insertion of the ureter in one case. In six patients with retrovesical complex formations (suspicious for an ectopic cystic renal bud or a cystic genital structure) the 3D-CISS showed increased conspicuity scores for image quality.

Conclusion

The additional 3D-CISS-sequence increases the diagnostic yield in the pelvis in children with complex malformations of the lower UGT such as ectopic ureteral insertion or suspected cystic renal or genital malformations at only minimal additional time, compared to standard MR-urography.     

Radiology as part of an objective structured clinical examination on clinical skills

Introduction

An objective structured clinical examination (OSCE) assessess clinical competence in a standardised and context related manner. Compared with written tests, OSCE's are more susceptible to reliability errors because of the use of multiple cases and multiple examiners. In the pre-clinical phase of the medical curriculum of the University Medical Centre Utrecht, an OSCE is organised as a medical consult. We evaluated the radiology station.

Method

Four questions were formulated:

•

What is the internal consistency of the items of the radiology station?

•

How do the scores on the radiology station compare with the scores on the test excluding radiology?

•

How do different cases differ in scores?

•

What are the differences in score between the examiners?

We analysed the OSCE results of second year medical students in 2004.

Results

Two hundred and sixty-five students were examined in the OSCE in 2004. Ninty-three Students were examined in the radiology station. Cronbach's alpha coefficient for the radiology station was 0.92. The average score for the radiology station was 3.8 (0.87). The average score for the test without radiology was 3.9 (0.32). The range of the average scores for the six different cases was 0.5 (3.6-4.1). The range of the average scores for the five examiners was 1.0 (3.3-4.3).

Conclusion

The internal consistency of the items in the radiology station is good. The average score for the radiology station is similar to that of the other stations. The range of the scores between the different cases was relatively small. The range of the scores between the different examiners was clearly larger.     

The infiltration of the AC joint performed by one specialist: Ultrasound versus palpation a prospective randomized pilot study

Introduction

The acromio-clavicular (AC) joint is very susceptible to degenerative processes that result in pain and functional impairment. One common modality of treatment has been local infiltration of the joint space. Although this procedure has produced notable positive results, needle misplacement occurs frequently. The aim of this investigation is to evaluate the effects of an intra articular infiltration by comparing precise needle placement into the joint space using high-resolution-ultrasound with the conventional palpation technique.

Methods

This prospective and randomized pilot study analysed 20 patients who were assigned either to the “ultrasound” or the “palpation” group. Clinical examinations were performed before treatment and at 1 h, 1 week and 3 weeks after a single infiltration of local anaesthetic and corticoid carried out by one specialist.

Results

In both groups significant improvement in pain and function was obtained up to one-week post injection. Function remained significantly improved until the last follow-up and did not differ between the two groups. The agent was administered in all patients into the joint space in the ultrasound group.

Conclusion

Ultrasound guided infiltration of the AC joint is an easily achieved procedure without any complications. However, clinical follow-up did not differ between free-hand and ultrasound-guided AC joint space infiltration.     

Added value of 80 kVp images to averaged 120 kVp images in the detection of hepatocellular carcinomas in liver transplantation candidates using dual-source dual-energy MDCT: Results of JAFROC analysis

Background

To assess the added value of 80 kVp images to weighted average 120 kVp images for detecting hepatocellular carcinomas (HCCs) using dual-source, dual-energy MDCT.

Materials and methods

Forty-one HCCs in 42 patients who underwent liver transplantation (LT) were included. All patients underwent quadruple-phase CT using a 64-row dual-source, dual-energy MDCT with 80 kVp and 140 kVp. For 120 kVp, a linear blending ratio of 0.3 was chosen. Interval reviews for both simulated 120 kVp images without and with pure 80 kVp data were performed independently by two radiologists. They detected HCCs using a 4-point confidence scale. Tumor-to-liver contrast-to-noise ratio (CNR) was calculated and compared between the 80 kVp and simulated 120 kVp images. The additional diagnostic value of 80 kVp images was evaluated by jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis.

Results

There were 41 HCCs on pathology and 37 of the 41 HCCs were depicted on CT scan. The mean CNR of the 37 HCCs in late arterial and portal-phase images was significantly better in the 80 kVp images than in 120 kVp images. The average JAFROC figure of merit, however, was not significantly improved when 80 kVp was added. Furthermore, the number of false-positives was significantly increased in reader 1 when adding 80 kVp data.

Conclusion

The addition of 80 kVp CT images to simulated 120 kVp images did not significantly improve the detection of HCCs despite of the significantly better CNR of 80 kVp images.     

The synthesis of a D-glucosamine contrast agent, Gd-DTPA-DG, and its application in cancer molecular imaging with MRI

Objective

The purpose of this study is to describe the synthesis of Gadolinium-diethylenetriamine pentaacetic acid-deoxyglucosamine (Gd-DTPA-DG) which is a d-glucosamine metabolic MR imaging contrast agent. We will also discuss its use in a pilot MRI study using a xenograft mouse model of human adenocarcinoma.

Methods

This novel contrast agent was specifically studied because of its ability to “target” metabolically active tumor tissues. In this study Gd-DTPA-DG is used to investigate how tumor tissues would react to a dose of 0.2 mmol Gd/kg over a 120 min exposure in a xenograft mouse model. These experiments used athymic mice implanted with human pulmonary adenocarcinoma (A549) as demonstrated by dynamic MRI. Alternately, another contrast agent that is not specific for targeting, Gd-DTPA, was used as the control at a similar dose of gadolinium. Efficacy of the targeted contrast agent was assessed by measuring relaxation rate in vitro and signal intensity (SI) in vivo. Statistical differences were calculated using one-way analysis of variance.

Results

The synthesized Gd-DTPA-DG was shown to improve the contrast of tumor tissue in this model. Gd-DTPA-DG was also shown to have a similar pharmacokinetic rate but generated a higher relaxation rate in tumor tissues relative to the control contrast Gd-DTPA. In comparison to the pre-contrast imaging, the SI of tumor tissue in the experimental group was shown to be significantly increased at 15 min after injection of Gd-DTPA-DG (p < 0.001). The enhanced signal intensity spread from the edge of the tumor to the center and seemed to strengthen the idea that MRI performance would be useful in different tumor tissues.

Conclusion

This preliminary study shows that this new chelated contrast agent, Gd-DTPA-DG, can be specifically targeted to accumulation in tumor tissue as compared to normal tissues. This targeted paramagnetic contrast agent has potential for specific cancer molecular imaging with MRI.     

Learning from diagnostic errors: a good way to improve education in radiology

Purpose

To evaluate the causes and the main categories of diagnostic errors in radiology as a method for improving education in radiology.

Material and methods

A Medline search was performed using PubMed (National Library of Medicine, Bethesda, MD) for original research publications discussing errors in diagnosis with specific reference to radiology. The search strategy employed different combinations of the following terms: (1) diagnostic radiology, (2) radiological error and (3) medical negligence. This review was limited to human studies and to English-language literature. Two authors reviewed all the titles and subsequently the abstracts of 491 articles that appeared pertinent. Additional articles were identified by reviewing the reference lists of relevant papers. Finally, the full text of 75 selected articles was reviewed.

Results

Several studies show that the etiology of radiological error is multi-factorial. The main category of claims against radiologists includes the misdiagnoses. Radiologic “misses” typically are one of two types: either missed fractures or missed diagnosis of cancer. The most commonly missed fractures include those in the femur, the navicular bone, and the cervical spine. The second type of “miss” is failure to diagnose cancer. Lack of appreciation of lung nodules on chest radiographs and breast lesions on mammograms are the predominant problems.

Conclusion

Diagnostic errors should be considered not as signs of failure, but as learning opportunities.     

Facilitating cartilage volume measurement using MRI

Purpose

To compare quantitative cartilage volume measurement (CVM) using different slice thicknesses.

Materials and methods

Ten knees were scanned with a 1.5 T MRI (Sonata, Siemens, Erlangen, Germany) using a 3D gradient echo sequence (FLASH, fast low-angle shot). Cartilage volume of the medial and lateral tibial plateau was measured by two independent readers in 1.5 mm, 3.0 mm and 5.0 mm slices using the Argus^® software application. Accuracy and time effectiveness served as control parameters.

Results

Determining cartilage volume, time for calculation diminished for the lateral tibial plateau from 384.6 ± 127.7 s and 379.1 ± 117.6 s to 214.9 ± 109.9 s and 213.9 ± 102.2 s to 122.1 ± 60.1 s and 126.8 ± 56.2 s and for the medial tibial plateau from 465.0 ± 147.7 s and 461.8 ± 142.7 s to 214.0 ± 67.9 s and 208.9 ± 66.2 s to 132.6 ± 41.5 s and 130.6 ± 42.0 s measuring 1.5 mm, 3 mm and 5 mm slices, respectively. No statistically significant difference between cartilage volume measurements was observed (p > 0.05) while very good inter-reader correlation was evaluated.

Conclusion

CVM using 1.5 mm slices provides no higher accuracy than cartilage volume measurement in 5 mm slices while an overall time saving up to 70% is possible.     

Perfusion patterns of metastatic gastrointestinal stromal tumor lesions under specific molecular therapy

Rationale and objective

The aim of this pilot study was the evaluation of CT perfusion patterns in metastatic GIST lesions under specific molecular therapy with sunitinib or imatinib both in responders and non-responders.

Patients and methods

24 patients with metastatic GIST under tyrosine kinase inhibition were retrospectively evaluated. A total of 46 perfusion and venous phase CT scans were acquired. Volume of distribution, blood flow, blood volume, permeability and hepatic perfusion index measurements of metastatic lesions were carried out. Lesions were classified as “good response” or “poor response” to therapy, and perfusion parameters were compared for these two types of lesions.

Results

24 patients were evaluated. In the extrahepatic abdominal lesions (N = 15), good responders showed significant lower perfusion values than poor responders (volume of distribution: 3.3 ± 2.0 vs. 13.0 ± 1.8 ml/100 ml, p = 0.001). The same tendency was observed in intrahepatic lesions (N = 31) (liver volume of distribution: 2.1 ± 0.3 vs. 7.1 ± 1.3 ml/100 ml, p = 0.003); (hepatic perfusion index: 24.3 ± 7.9 vs. 76.1 ± 1.5%, p = 0.0001).

Conclusion

Our data indicate that there are characteristic perfusion patterns of metastatic GIST lesions showing a good or poor response to molecular pharmacotherapy. Perfusion should be further evaluated in cross-sectional imaging studies as a possible biomarker for treatment response in targeted therapies of GIST.     

Cardiac CT angiography after coronary artery surgery in children using 64-slice CT scan

Objective

The purpose of this study was to compare the diagnostic accuracy of 64-slice CT with that of invasive angiography in the detection of graft and/or coronary angioplasty stenosis in children who had undergone coronary artery surgery.

Population and methods

Fifteen consecutive children (8 male and 7 female; age 9.2 ± 6.1 years) underwent 64-slice CT because of chest pain or ECG changes mean 4.8 ± 3.7 years after surgical coronary artery surgery; 10 patients had coronary angioplasty using a patch from the saphenous vein, four had mammary artery bypass, and one had saphenous vein bypass. Six main segments of the coronary arteries and all the bypass graft considered as a single segment were analyzed and compared with invasive angiography used as the reference standard.

Results

CT correctly identified the four children with coronary angioplasty and mammary graft lesions that were confirmed by conventional angiography: one patient had a significant stenosis (>50% stenosis) at the mammary bypass graft anastomosis site; three other had non-significant stenosis (<50% stenosis) including a mild lesion of the saphenous vein patch in two patients and a mild lesion at the anastomosis site of the mammary bypass in one. All segments identified as normal by CT in the other 11 children were also found to be normal by conventional angiography.

Conclusion

In centers expert in this technique, 64-slice CT scanning is a promising, rapid, and useful diagnostic technique for evaluating both coronary angioplasty and bypass graft lesions in children who had undergone coronary artery surgery.     

Measurement of canine pancreatic perfusion using dynamic computed tomography: Influence of input-output vessels on deconvolution and maximum slope methods

Objective

We investigated whether the prerequisite of the maximum slope and deconvolution methods are satisfied in pancreatic perfusion CT and whether the measured parameters between these algorithms are correlated.

Methods

We examined nine beagles injected with iohexol (200 mgI kg⁻¹) at 5.0 ml s⁻¹. The abdominal aorta and splenic and celiac arteries were selected as the input arteries and the splenic vein, the output veins. For the maximum slope method, we determined the arterial contrast volume of each artery by measuring the area under the curve (AUC) and compared the peak enhancement time in the pancreas with the contrast appearance time in the splenic vein. For the deconvolution method, the artery-to-vein collection rate of contrast medium was calculated. We calculated the pancreatic tissue blood flow (TBF), tissue blood volume (TBV), and mean transit time (MTT) using both algorithms and investigated their correlation based on vessel selection.

Results

The artery AUC significantly decreased as it neared the pancreas (P < 0.01). In all cases, the peak time of the pancreas (11.5 ± 1.6) was shorter than the appearance time (14.1 ± 1.6) in the splenic vein. The splenic artery-vein combination exhibited the highest collection rate (91.1%) and was the only combination that was significantly correlated between TBF, TBV, and MTT in both algorithms.

Conclusion

Selection of a vessel nearest to the pancreas is considered as a more appropriate prerequisite. Therefore, vessel selection is important in comparison of the semi-quantitative parameters obtained by different algorithms.