Raju Sharma

Respiratory-Triggered Versus Breath-Hold Diffusion-Weighted MRI of Liver Lesions: Comparison of Image Quality and Apparent Diffusion Coefficient Values

OBJECTIVE The purpose of our study was to compare respiratory-triggered and breath-hold diffusion-weighted liver MRI and to assess the agreement in the apparent diffusion co-efficient (ADC) values between the two sequences. MATERIALS AND METHODS Forty-eight patients (27 men, 21 women; mean age, 45.2 years) with focal liver lesions underwent respiratory-triggered and breath-hold diffusion-weighted MRI (DWI) in addition to routine MRI. Both sequences had identical imaging parameters except for signal averages, which were 6 in respiratory-triggered and 2 in breath-hold sequences. A total of 92 lesions (maximum of three lesions per patient; 37 benign, 55 malignant) were evaluated. Lesions were confirmed by typical imaging appearance, histopathology, or follow-up. Signal-to-noise ratio (SNR) of the liver, contrast-to-noise ratio (CNR), and relative contrast ratio of the lesions were measured in each DWI sequence and were statistically compared using the Mann-Whitney U test. The ADC values of normal liver and each category of liver lesions in the two sequences were compared for agreement using Pearsons coefficient and reliability analysis scale. RESULTS The SNR of the normal liver was significantly better on respiratory-triggered DWI than on breath-hold DWI. The mean CNR of metastases, hepatocellular carcinomas, and abscesses was significantly better in the respiratory-triggered DWI than in the breath-hold DWI sequences. The ADC values of liver and focal lesions measured by the two techniques showed good agreement. The SDs of the ADC values of normal liver were similar in the two sequences. CONCLUSION Respiratory-triggered DWI should be preferred over breath-hold DWI for the evaluation of focal liver lesions because it provides better image quality and SNR without any compromise in the calculated ADC values.

Prevalence and progression of basal ganglia calcification and its pathogenic mechanism in patients with idiopathic hypoparathyroidism

The pathogenesis of basal ganglia calcification (BGC) in hypoparathyroidism is not clear. Its occurrence in hypocalcaemic milieu of hypoparathyroidism is believed to be due to high serum calcium–phosphorus product and poor calcium control.

Imaging the Inferior Vena Cava: A Road Less Traveled

A broad spectrum of congenital anomalies and pathologic conditions can affect the inferior vena cava (IVC). Most congenital anomalies are asymptomatic; consequently, an awareness of their existence and imaging appearances is necessary to avoid misinterpretation. Imaging also plays a central role in the diagnosis of Budd-Chiari syndrome secondary to membranous obstruction of the intrahepatic IVC. Primary malignancy of the IVC is far less common than intracaval extension of malignant tumors arising in adjacent organs, and imaging can accurately help determine the presence and extent of tumor thrombus, information that is crucial for surgical planning. However, the radiologist should be aware that artifactual filling defects at computed tomography and magnetic resonance imaging can mimic true thrombus in the IVC and must be able to differentiate true from pseudo filling defects. Other imaging findings such as flat IVC and early enhancement of the IVC are useful in limiting the differential diagnosis. Familiarity with the imaging features of the various congenital and pathologic entities that can affect the IVC is paramount for early diagnosis and management.

Whole-body MR imaging with the use of parallel imaging for detection of skeletal metastases in pediatric patients with small-cell neoplasms: comparison with skeletal scintigraphy and FDG PET/CT

BackgroundIn pediatric patients with small-cell tumors, there is an increasing demand for accurate and early detection of skeletal, especially bone marrow, metastases as new treatment protocols are introduced. Whole-body MR imaging (WB-MR) and 18F-fluorodeoxyglucose PET/CT (FDG PET/CT) are new promising imaging methods that can detect metastases before osteoblastic host response occurs, which is the basis for detection of metastases by skeletal scintigraphy (SSC).ObjectiveTo assess the ability of WB-MR to detect marrow metastases in children with small-cell neoplasms and compare its performance with that of FDG PET/CT and SSC.Materials and methodsDuring a 16-month period, 26 children and adolescents with histopathologically proven small-cell neoplasms underwent WB-MR, FDG PET/CT and Tc-phosphonate-based SSC in a random order within a 25-day period. Metastases were localized in relation to eight regions of the body.ResultsWB-MR revealed metastases in 39 out of a total of 208 regions in 26 patients (sensitivity 97.5%, specificity 99.4%, positive predictive value 97.5%, negative predictive value 99.4%), SSC in 12 regions (sensitivity 30%, specificity 99.4%, PPV 92.3%, NPV 85.6%) and FDG PET/CT in 36 regions (sensitivity 90.0%, specificity 100%, PPV 100%, NPV 97.7%). Both WB-MR and FDG PET/CT showed excellent agreement (kappa) with the final diagnosis (96.9% and 93.6% respectively), whereas SSC showed only moderate agreement (39.6%).ConclusionOur results suggest that WB-MR and FDG PET/CT studies are robust imaging modalities for screening for skeletal metastases, and are far more accurate than SSC. The lack of radiation is an additional advantage of WB-MR, especially in the pediatric population.

Diffusion-weighted MRI in renal cell carcinoma: A surrogate marker for predicting nuclear grade and histological subtype:

Background Though previous investigators have attempted to evaluate its utility in characterization of focal renal lesions, diffusion-weighted MR imaging (DW MRI) in renal diseases is still an evolving field and its role in predicting the aggressiveness of renal cell carcinoma (RCC) is yet to be established. Purpose To assess whether apparent diffusion coefficient (ADC) values can be used to determine the nuclear grade and histological subtype of RCCs and to identify the tumor attributes contributing to variation in ADC values. Material and Methods The institutional ethics committee waived the requirement of informed consent for this retrospective study. The study cohort consisted of 33 patients who underwent MRI (with diffusion-weighted imaging at b values of 0 and 500 s/mm2) and were found to have 36 pathologically-proven RCCs. ADC values were determined for solid portions of RCC, cystic/hemorrhagic areas, and normal renal parenchyma. Histological subtype, nuclear grade, and cell count were determined for each lesion. ADC values were compared between different grades and subtypes and correlation with cell count was investigated. Receiver operating characteristic curves were drawn to establish cut-off ADC values. Results There were 23 low grade (grades I and II) and 13 high grade tumors (grades III and IV). There were 32 clear-cell and four non-clear-cell RCCs. A decreasing trend of ADC values was seen with increasing grade and mean ADC of high grade RCC was significantly lower than low grade (1.3145 vs 1.6982 × 10−3 mm2/s) (P = 0.005). Mean ADC for clear-cell RCC was significantly higher than non-clear-cell RCC (1.6245 vs. 1.0412 × 10−3 mm2/s) (P = 0.005). ADC values higher than 1.7960 × 10−3 mm2/s were seen only with low grade and values greater than 1.4904 × 10−3 mm2/s were seen only with clear-cell RCC. Conclusion ADC values provide a non-invasive means to predict the nuclear grade and histological subtype of RCC. Cellularity and morphology are other tumor attributes contributing to the variation in ADC values of RCCs.

Role of (68)Ga-DOTATOC PET-CT in the diagnosis and staging of pancreatic neuroendocrine tumours.

ObjectiveThe objective of the present study was to evaluate the role of 68Ga-DOTA(0)-Phe(1)-Tyr(3)-octreotide (68Ga-DOTATOC) positron emission tomography computed tomography (PET-CT) for detection and staging of pancreatic neuroendocrine tumours (NETs).MethodsTwenty patients with clinically suspected and/or histopathologically proven pancreatic NET underwent 68Ga-DOTATOC PET-CT imaging for staging and /or localisation of primary lesion. They also underwent contrast enhanced CT (CECT) and 8 patients underwent 18F-FDG PET-CT. SUVmax of primary and metastatic lesions were measured. Results were verified with histopathology for primary tumour and with clinical follow up/MRI and /or biopsy for metastatic disease. Results of 68Ga-DOTATOC PET-CT were compared to CECT and 18F-FDG PET-CT.Results68Ga-DOTATOC PET-CT correctly localised primary in all 20, CECT in 15 and 18F-FDG PET-CT in 2 patients. 68Ga-DOTATOC PET-CT demonstrated metastases in 13 patients, CECT in 7 and 18F-FDG PET-CT in 2. 68Ga-DOTATOC PET-CT emerged as the best investigation with 100% sensitivity and PPV for detecting primary tumour and metastatic disease. The detection rate of CECT was lower than 68Ga-DOTATOC PET-CT, both for primary tumour (20vs.15) or metastatic disease (13vs.7). 18F-FDG PET-CT performed poorly for primary and metastasis.ConclusionGa-DOTATOC PET-CT is a very useful imaging investigation for diagnosing and staging pancreatic NET.

Differentiation between benign and malignant hilar obstructions using laboratory and radiological investigations: A prospective study

BACKGROUND Preoperative determination of the aetiology of bile duct strictures at the hilum is difficult. We evaluated the diagnostic accuracy of laboratory parameters and imaging modalities in differentiating between benign and malignant causes of hilar biliary obstruction. PATIENTS AND METHODS Fifty-eight patients (26 men) with a history of obstructive jaundice and liver function tests (LFTs) and ultrasound suggestive of biliary obstruction at the hilum were studied. They were evaluated by tumour marker assay (CA19-9), CT and MRI/MRCP. A single experienced radiologist, blinded to the results of other tests, evaluated the imaging. The final diagnosis was made either from histology of the resected specimen, operative findings or image-guided biopsy in inoperable patients. A receiver operator characteristic (ROC) curve was constructed for each laboratory parameter to determine optimal diagnostic cut-off to predict malignant biliary stricture (MBS). RESULTS In all, 34 patients had a benign and 24 had malignant aetiology. The mean age of benign patients was 38 years compared with 54 years for MBS. Forty-seven patients were treated with surgery while 11 had ERCP/PTC and stenting. The ROC curve showed that preoperative bilirubin level >8.4 mg/dl (sensitivity 83.3%, specificity 70%), alkaline phosphatase level >478 IU (sensitivity 63%, specificity 49%) and CA19-9 levels >100 U/L (sensitivity 45.8%, specificity 88.2%) for predicting MBS. The sensitivity, specificity and diagnostic accuracy of MRI/MRCP (87.5%, 85.3%, 82.7%, respectively) was marginally superior to CT (79.2%, 79.4%, 79.3%, respectively). CONCLUSIONS Patients with a bilirubin level of >8.4 mg% and CA19-9 level >100 U/L were more likely to have malignant aetiology. MRI/MRCP was a better imaging modality than CT.

Neuropsychological dysfunction in idiopathic hypoparathyroidism and its relationship with intracranial calcification and serum total calcium

BACKGROUND There is limited information on neuropsychological and neurological dysfunctions in patients with idiopathic hypoparathyroidism (IH). OBJECTIVE To assess neuropsychological and neurological dysfunctions in IH and its associated factors in a cross-sectional design. METHOD Neuropsychological functions were assessed in 62 patients with IH and 70 controls using a battery of cognitive tests. Neurological assessment included extrapyramidal and cerebellar signs. Assessment of intracranial calcification and volume of basal ganglia calcification (BGC) were made on computed tomography and of calcium control by averaging serum total calcium values available during the follow-up. RESULTS A significantly higher proportion of patients with IH showed neuropsychological dysfunctions than controls (32.3 (95% CI: 20.9-45.3) vs 5.7% (95% CI: 1.6-14.0), P<0.001). Neurological signs were present in 35.5% patients (extrapyramidal: 16.1%; cerebellar: 20.9%). Volume of BGC and number of sites with intracranial calcifications including cerebellum/dentate were comparable in patients with and without neuropsychological, extrapyramidal or cerebellar dysfunctions. Cognitive dysfunction score was lower by 1.7 points in males than in females (P=0.02) and increased by 0.21 and 5.5 for each year increase in the duration of illness (P=0.001) and one unit increase in serum calcium-phosphorus product (P=0.01) respectively. The scores improved by 0.27 for every mg% increase in serum calcium (P=0.001). CONCLUSION Neuropsychological dysfunctions are present in up to one-third of patients with IH and correlate with duration of illness, female gender, serum calcium and calcium-phosphorus product during follow-up but not with intracranial calcification. These dysfunctions may affect their daily functions, safety and drug compliance.

MRI and MR sialography of juvenile recurrent parotitis

BackgroundJuvenile recurrent parotitis (JRP) is the second most common inflammatory salivary gland disease of childhood, after mumps. Diagnosis of JRP is usually based on clinical history of recurrent unilateral or bilateral parotid swelling and demonstration of sialectasis. Conventional sialography, digital sialography, US, MRI and sialoendoscopy have been used as investigative tools for the diagnosis of JRP. MR sialography is increasingly recognized as a useful supplement to sialography in salivary duct disorders.ObjectiveTo describe the MRI and MR sialographic findings in children with JRP.Materials and methodsMR Sialography was performed using T2-weighted three-dimensional constructive interference in steady-state (CISS) and half fourier acquisition single-shot turbo spin-echo (HASTE) sequences in 62 children with inflammatory salivary gland disease. Out of these 62 children, 6 had JRP. Axial T1- and T2-W images were also performed.ResultsThe main parotid duct was normal in all six children with JRP. High signal intensity focal lesions suggestive of sialectasis were seen involving both parotid glands in all six children. CISS sequence demonstrated the intraglandular ducts and sialectasis better than HASTE images.ConclusionMRI and MR sialography can non-invasively delineate the parenchymal and ductal system abnormalities of the parotid glands in children with JRP. Although MR and MR sialography cannot substitute US, they can accurately depict findings such as sialectasis and signal intensity changes in the parotid gland depending upon the phase of the disease (acute vs. chronic inflammation). The radiologist should be familiar with MR findings of JRP.

The role of magnetic resonance imaging in fetal renal anomalies

To evaluate the role of magnetic resonance imaging (MRI) in fetuses with suspected renal anomalies after ultrasonography.