Choice Of Diagnostic Modality Research Articles

An elderly man with fecal materials in the Foley catheter

A 70-year-old man presented to the emergency department with a 2-week history of watery diarrhea. Fecal materials were found in the Foley catheter. A computed tomography of the abdomen and pelvis revealed chronic diverticulitis with enterovesical fistula. The patient was treated with broad-spectrum antibiotics and underwent an urgent surgery with a transverse loop colostomy. The presence of fecaluria should raise the clinical suspicion of enterovesical fistula. Computed tomography is the choice of diagnostic modality.

Rare causes of acute abdomen in pregnancy: “ultrasound to the rescue”. A review of two cases

Abstract Acute abdomen in pregnancy poses special challenge to the pregnant woman, her unborn infant, and the attending physician. The problems are multifactorial, as the physiological changes in pregnancy mask some of the clinical signs that can be elicited in making accurate diagnosis. Some diagnostic modalities are not feasible in pregnancy because of their effects on the fetus. Another dilemma is that two lives are at stake. It becomes even more challenging when one is faced with rare causes. For these reasons, the choice of diagnostic modality becomes critical. The chosen diagnostic modality should not only be readily available, non-invasive, least hazardous to the mother and fetus, but should also provide adequate information to enable accurate diagnosis. Ultrasonography provides such an opportunity and should be utilized whenever the need arises. We present two cases of acute abdomen in pregnancy managed at Abubakar Tafawa Balewa University Teaching Hospital: one was seen in the third trimester and the other in the first trimester, each with its peculiar presentation. The review is meant to alert obstetricians on the critical role of ultrasound in enhancing accurate diagnosis in the face of a complex clinical condition like acute abdomen in pregnancy.

Radiological diagnosis in lung disease: factoring treatment options into the choice of diagnostic modality.

Chest X-ray, computed tomography (CT), and magnetic resonance imaging (MRI) each have characteristic advantages and disadvantages that need to be considered in clinical decision-making. This point is discussed in reference to the main types of lung disease that are encountered in practice. A selective literature search was performed in the PubMed and Google Scholar databases. Existing clinical guidelines on the main types of lung disease and studies concerning radiological diagnosis were also con - sidered in this review. There have been no more than a few large-scale, controlled comparative trials of different radiological techniques. Chest X-ray provides general orientation as an initial diagnostic study and is especially useful in the diagnosis of pneumonia, cancer, and chronic obstructive pulmonary disease (COPD). Multi-detector CT affords nearly isotropic spatial resolution at a radiation dose of only 0.2-5 mSv, much lower than before. Its main indications, according to current guidelines, are tumors, acute pulmonary embolism, pulmonary hypertension, pulmonary fibrosis, advanced COPD, and pneumonia in a high-risk patient. MRI is used in the diagnosis of cystic fibrosis, pulmonary embolism, pulmonary hypertension, and bronchial carcinoma. The positive predictive value (PPV) of a chest X-ray in outpatients with pneumonia is only 27% (gold standard, CT); in contrast, an initial, non-randomized trial of MRI in nosocomial pneumonia revealed a PPV of 95%. For the staging of mediastinal lymph nodes in bronchial carcinoma, MRI has a PPV of 88% and positron emission tomography with CT (PET/CT) has a PPV of 79%, while CT alone has a PPV of 41% (gold standard, histology). The choice of radiologicalal technique for the detection, staging, follow-up, and quantification of lung disease should be based on the individual clinical options, so that appropriate treatment can be provided without excessive use of diagnostic testing.

The Complementary Roles of Radionuclide Myocardial Perfusion Imaging and Cardiac Computed Tomography

Despite recent dramatic advances in managing patients with cardiovascular disease (CVD), it still accounts for more deaths in the United States than any other medical condition. American Heart Association Statistics show that CVD accounts for 33.6% deaths, 1 every 39 seconds. 1 Costs are estimated at $286 billion, more than the cost of cancer. Given its large burden, the need for assessing CVD in an accurate, safe, and cost-effective manner is great. Noninvasive imaging has been the primary modality to effectively diagnose coronary artery disease (CAD) and, more importantly, risk stratify patients by separating low-risk patients who can be treated conservatively from those at high risk who need more aggressive management. Imaging can also be used to monitor disease progression, direct further evaluation, and guide changes in treatment. Although there is overlap, some noninvasive imaging modalities focus on cardiac physiology/function, whereas others focus on anatomy. Functional imaging consists mainly of techniques that detect physiologically significant coronary artery narrowings. Stress single-photon emission computed tomography (SPECT) radionuclide myocardial perfusion imaging (MPI) and stress echocardiography are most widely used for this purpose, although perfusion techniques with computed tomography (CT) and magnetic resonance imaging are under investigation. 2 In particular, stress MPI can accurately diagnose CAD, measure left ventricular (LV) function, risk stratify patients, and assess myocardial viability in situations of LV dysfunction. MPI, most often using singlephoton‐emitting radiotracers, is widely used and cost-effective, and its utility is supported by a large body of literature. New technology and techniques promise to overcome current limitations of MPI. In addition, CVD is more than CAD, and nuclear imaging shows promise for evaluating myocardial disease in the setting of congestive heart failure (CHF). Anatomic imaging of CAD focuses on visualization of the epicardial coronary arteries and perfused myocardium. One can quantify coronary artery calcium (CAC) reflecting disease extent, or directly visualize coronary lumens and plaque using CT angiography. Many investigators are also exploring approaches that combine functional and anatomical evaluation,eitherinsequenceorinonesetting(ie,hybridimaging), to give a more complete cardiovascular evaluation and help overcome the limitations of each modality. Hybrid imaging may be particularly useful for identifying culprit lesions, for coronary plaque imaging and in CHF. This review will examine the strengths and weaknesses of radionuclide MPI and CT imaging techniques, and explore how they provide complementary information. Throughout, one must consider that the choice of diagnostic modality should rely on not only availability and effectiveness but also each patient’s unique clinical presentation.

Patterns of Relapse and Value of Follow up Procedures in Patients with Diffuse Large B Cell Lymphoma (DLBCL) Who Achieve a Complete Remission (CR)

Purpose: Optimal follow up schedule and choice of diagnostic modalities have not been well studied in patients with DLBCL who achieve CR after initial treatment. We analyzed patterns of relapse in patients with DLBCL who were treated with CHOP±R therapy and achieved CR in our institution between 1999 and 2007. We generally follow such patients with physical exam and blood tests including LDH every 3 months and CT scans every 3 to 6 months for the first two years. Follow up schedule varied afterwards.Patients and methods: Thirty-eight patients experienced relapse, in whom we first determined if relapse was detected by symptoms which prompted diagnostic processes such as imaging studies and/or biopsy or by prescheduled follow up blood test or systemic CT scans. Other characteristics of these patients including time from diagnosis to relapse, time from last systemic CT scan that showed no evidence of disease to relapse, and time from relapse to death were analyzed.Results: Twenty-seven patients (71%) presented with symptoms (“symptomatic patients”); 12 with palpable superficial masses, 5 with local pain, 5 with neurological symptoms due to central nervous system (CNS) involvement, 2 with persistent fever, 1 with gastrointestinal bleed, 1 with nasal congestion and 1 with persistent cough. Eleven patients (29%) were asymptomatic when relapse was detected (“asymptomatic patients”). Two showed elevated serum LDH levels which prompted imaging studies leading to the diagnoses. Nine were found to have relapsed diseases by prescheduled systemic CT scans. Among 27 symptomatic patients, 7 (18% of all relapses) had diseases that were not detectable by CT scans (5 isolated CNS relapses, 1 GI relapse, and 1 subcutaneous relapse in upper extremity). Patient characteristics at the time of initial diagnosis were similar in the two groups. Median time from initial diagnosis to relapse in symptomatic and asymptomatic patients were 11.9 months (range 3.8–98.1) and 12.5 months (range 7.2–50.7), respectively (p=0.635). Median time from last systemic CT scan to relapse were 2.9 months (range 0.1–33.0) and 5.2 months (range 1.9–10.8), respectively (p=0.895). Time from relapse to death of any cause were similar in the 2 groups (log-rank p=0.423) but the median time was longer in asymptomatic patients (16.6 months vs 39.8 months). Since late relapses potentially tend to be detected by symptoms due to infrequent CT scans, analyses were next limited only to those who relapsed within 2 years after diagnosis. The results were similar between symptomatic and asymptomatic group.Conclusions: This study showed that more than two thirds of patients were symptomatic at the time of relapse. And up to 18% of relapsed diseases were undetectable by routine CT scans. Half of “symptomatic” patients noticed their symptoms less than three months after last CT scan, suggesting that even every 3 months CT would miss these relapses before patients were symptomatic. Longer median survival (though the overall difference was not significant) in “asymptomatic patient” could be attributed in part to “early detection of relapse and intervention” but in contrast, asymptomatic patients might have had less aggressive diseases allowing prescheduled CT scans to detect the diseases before they are symptomatic. Important question is whether delaying detection of relapse and treatment till patient is symptomatic would be associated with worse clinical outcome. This question is also translated into whether routine CT scan is even necessary, and if so, what is the optimal schedule of imaging studies. Answers to these questions may depend on the estimated risk of relapse based on various prognostic factors. Larger scale studies are needed in this area.

901-28 Lack of Correlation Between Relief of Chest Pain After Sublingual Nitroglycerin and Reversible Radionuclide Perfusion Defects or Presence of Significant Coronary Atherosclerosis on Coronary Angiography

To investigate whether relief of chest pain (CP) ≤ 5 mins after sublingual nitroglycerin (NTG) is of value for judging whether acute cardiac ischemia is likely to be present, we compared the response to sublingual NTG (no relief vs. relief of CP) with results of a rest/stress technetium-99m sestamibi gated SPECT perfusion imaging study performed the next working day (85 patients, 37 M 49 F, age 52 ± 13) or coronary angiography performed within 72 hours (38 patients, 20 M 18 F, age 55 ± 13) in adult patients who presented to the emergency department with non-traumatic chest pain and a nondiagnostic electrocardiogram. The choice of diagnostic modality was made clinically by the emergency department physicians. Results were as follows: Stress Study Coronary Angiography No reversible defect Reversible defect ≥70% stenosis <70% stenosis No relief 47 10 7 14 Relief 25 3 5 12 There was no significant relati nship between the clinical response of chest pain to NTG and 1) the presence of a reversible radionucleide perfusion defect on stress testing (p = 0.31) or 2) the finding of significant (≥70%) coronary atherosclerotic narrowing in at least one major epicardial coronary vessel (p = 0.54) on coronary angiography. We conclude that the response to NTG does not accurately predict the presence of either physiologically or anatomically significant coronary disease in patients who present to the emergency department with chest pain and a nondiagnostic electrocardiogram. Therefore, the presence or absence of a clinical response to NTG should not be considered to be of diagnostic significance in this setting.