Israel Medical Association Journal

Background: Despite the lack of clinical studies supporting the use of routine surveillance FDG-positron emission tomography (PET) in patients with diffuse large B cell lymphoma (DLBCL) who achieved remission, many centers still use this strategy, especially in high risk patients. Surveillance FDG-PET computed tomography (CT) is associated with a high false positive (FP) rate in DLBCL patients. 

Objectives: To investigate whether use of specific CT measurements could improve the positive predictive value (PPV) of surveillance FDG-PET/CT. 

Methods: This retrospective study included DLBCL patients treated with CHOP or R-CHOP who achieved complete remission and had at least one positive surveillance PET. CT-derived features of PET-positive sites, including long and short diameters and presence of calcification and fatty hilum within lymph nodes, were assessed. Relapse was confirmed by biopsy or consecutive imaging. The FP rate and PPV of surveillance PET evaluated with/without CT-derived measurements were compared. 

Results: Seventy surveillance FDG-PET/CT scans performed in 53 patients were interpreted as positive for relapse. Of these studies 25 (36%) were defined as true-positive (TP) and 45 (64%) as FP. Multivariate analysis found long or short axis measuring ≥ 1.5 and ≥ 1.0 cm, respectively, in PET-positive sites, International Prognostic Index (IPI) ≥ 2, lack of prior rituximab therapy and FDG uptake in a previously involved site, to be independent predictors of true positive surveillance PET (odds ratio 5.4, 6.89, 6.6, 4.9, P < 0.05 for all). 

Conclusion: PPV of surveillance PET/CT may be improved by its use in selected high risk DLBCL patients and combined assessment of PET and CT findings.

 

Background: Trans-catheter valve implantation (TAVI) is a non-surgical alternative for patients with severe aortic stenosis (AS). Pre-procedural computed tomography angiography (CTA) allows accurate “road mapping,” aortic annulus sizing and the detection of incidental findings.

Objectives: To document the prevalence of non-valvular extra-cardiac findings on CTA prior to TAVI and the impact of these findings on the procedure.  

Methods: Ninety AS patients underwent CTA as part of pre-TAVI planning. Scans extended from the clavicles to the groin. Non-vascular non-valvular findings were documented and graded as follows: (A) significant findings causing TAVI cancellation or postponement, (B) significant findings leading to a change in the TAVI procedure approach, (C) non-significant findings not affecting the TAVI procedure. 

Results: TAVI was planned for 90 patients; their average age was 80.2 ± 7.5 years, 53% were females. Overall, non-valvular cardiac, extra-cardiac and extra-vascular significant and non-significant incidental findings were documented in 97% of scans (87/90). Significant pathologies causing TAVI cancellation or postponement (category A) were documented in 8%. Significant findings affecting the TAVI procedure (category B) were found in 16% of patients. 

Conclusions: Pre-TAVI CTA detected non-valvular extra-vascular pathologies leading to procedure cancellation/postponement or procedure modification in 8% and 16%, respectively. Comprehensive CTA evaluation that acknowledges the importance of such findings is of major importance since it might alter the TAVI procedure or even render it inappropriate. 

 

Abstract

Background: Only a few studies have compared the accuracy of magnetic resonance enterography (MRE) and computed tomography enterography (CTE) in the diagnosis of Crohn's disease and its complications.

Objectives: To compare the sensitivity of MRE and CTE analysis in their ability to detect, sign-by-sign, 10 classical imaging signs of Crohn's disease.

Methods: The study group comprised 42 biopsy-proven Crohn's disease patients who underwent both CTE and MRE within an average period of 6 weeks. Agreement between the two modalities in detecting the 10 most significant radiological signs of CD was evaluated using the Kappa index. The sensitivity of MRE and CTE was calculated using a standard of reference composed of all the findings seen by CTE and/or MRE. We analyzed MRE and CTE sensitivity separately in two groups, according to the time interval between the examinations.

Results: Agreement between CTE and MRE was more than 70% in 8 of the 10 signs: mural thickening, phlegmon, stenosis, skip lesions, mucosal stratification, fistula, abscess, and creeping fat. The Kappa level of agreement values for CTE versus MRE varied between substantial for phlegmon and skip lesions; moderate for fistula, creeping fat, abscess and mural thickening; and fair for stenosis and dilatation. CTE detected more findings than MRE, except for creeping fat and fistula. There was no significant difference in the sensitivity of CTE and MRE in the two groups defined by the time interval (time < 1.5 and time > 1.5 months) except for detection of dilatation.

Conclusions: Almost all imaging signs of Crohn's disease were detected equally well by both modalities regardless of the time interval between examinations. We therefore consider MRE to be reliable for imaging and follow-up in patients with Crohn's disease who may need recurrent imaging.

Background: Medical evaluation of a suspected meniscus injury begins with a history-taking and physical examination. Suspected meniscus injuries not responding to treatment are usually sent for imaging to confirm the diagnosis before arthroscopy. Tc-MDP bone single photon emission computed tomography (SPECT) scan has been suggested as an alternative to magnetic resonance imaging (MRI) in evaluating suspected knee meniscus tears.

Objectives: To examine the accuracy of knee SPECT as a tool to identify meniscus tears versus that of MRI as compared to the gold standard of arthroscopy.

Methods: The Israel Defense Forces database for 2005 through 2009 was searched according to the key words knee MRI, knee SPECT and knee arthroscopy. We identified 330 subjects who had undergone both a single knee SPECT and a single knee MRI prior to knee surgery. The medical files of 193 of the 330 subjects were randomly selected for review. A comparison was made between the preoperative SPECT and MRI studies and the arthroscopic finding. The sensitivity, specificity and accuracy were calculated.

Results: The subjects’ age was 21.3 ± 3.9. The agreement between SPECT and arthroscopy was 0.14 for the medial meniscus and 0.29 for the lateral meniscus. The agreement between MRI and arthroscopy was 0.59 for the medial meniscus and 0.69 for the lateral meniscus. SPECT scan was found to be 61% sensitive, 54% specific and 58% accurate in detecting common knee pathology, whereas MRI was found to be 95% sensitive, 67% specific and 85% accurate.

Conclusions: Knee SPECT has a lower sensitivity, specificity and accuracy than MRI in evaluating meniscal injuries and its use can result in increased unnecessary surgery.

Objectives: To evaluate the predictive value of V/Q scanning in patients with impaired renal function.

Methods: We assessed all patients with impaired renal function who underwent V/Q scanning. The patients studied included those who also had CTPA (group 1) and those who did not (group 2). We recorded the results of V/Q scanning, chest X-rays, CTPA, D-dimer levels, ultrasound of deep veins, and clinical probability for PE (Wells' score) in group 1. CTPA results were considered true results. Anticoagulant treatment was documented in all the patients.

Results: Of the 45 patients in group 1, 12 (22%) had positive CTPA for PE. The positive predictive value (PPV) for patients with high probability results on V/Q scanning for PE was 30%. Restricting results to D-dimer levels ≥ 1000 ng/ml added little to this value. Restricting results to Wells’ score ≥ 7 resulted in 72% PPV. The negative predictive values for low or moderate probability were ~79 % and ~67% respectively. Of the 95 patients in group 2, all those with high probability for PE were treated with anticoagulants.

Conclusions: Patients with impaired renal function and high probability for PE on V/Q scanning had very low PPV for PE. Due to the lack of CTPA studies, patients with high probability for PE on V/Q scanning were treated with anticoagulants.

Objectives: To assess the role of electrocardiography-gated CT-angiography (ECG-CTA) in the routine evaluation of CHD in neonates and infants particularly for the assessment of extracardiac findings.

Methods: The study cohort comprised 40 consecutive patients who underwent trans-thoracic echocardiography (TTE) and ECG-CTA. TTE and ECG-gated CTA findings regarding extracardiac vascular structures, coronary arteries and airways were compared with surgical or cardiac catheterization findings. Scans were evaluated for image quality using a subjective visual scale (from 1 to 4). Effective radiation dose was calculated for each scan.

Results: Median age was 28 ± 88 days and mean weight 3.7 ± 1.5 kg. Diagnostic quality was good or excellent (visual image score 3–4) in 39 of 40 scans (97.5%). ECG-CTA provided important additional information regarding extracardiac vascular structures and airway anatomy, complementing TTE in 75.6% of scans. Overall sensitivity of ECG-gated CTA for detecting extracardiac findings as compared with operative and cardiac catheterization findings was 97.6%. The calculated mean effective radiation dose was 1.4 ± 0.07 mSv (range 1.014–2.3 mSv).

Conclusions: ECG-CTA is an accurate modality for demonstrating extracardiac structures in complex CHD. It provides important complementary information to TTE regarding extracardiac vascular structures and coronary artery anatomy. This modality may obviate the need for invasive cardiac catheterization, thus exposing the patient to a much lower radiation dose.